Making a scanner with a DSLR

[Peter De Smidt]

http://i955.photobucket.com/albums/ae37/peterdesmidt/Light_House_2nd_Manual.jpg

[Kirk Gittings]

Huge improvement. That is with the new light source? I thought you were wrong about that but I think you were bang on.

[Peter De Smidt]

Well, it is with the new light source, but it's also with a different method. I manually positioned all of the pieces in Photoshop, using the difference blending mode and the arrow keys to nudge sections into place. It's about as much fun as counting the hairs on your own arm. It looked pretty good after doing that, but there were some slight, but obvious, tonal differences between the tiles. To get rid of that, I ran auto-blend-layers on the image layers. The result is pretty good, although it's an embarrassingly bad negative. I'll scan the negative, which I'm getting really sick of, tomorrow with my Cezanne, and then we can compare.

So far, it seems that the stitching programs do pretty well with negatives that have detail throughout, but they aren't ideal, or at least my use of them isn't ideal, with images with lots of low-detail areas. I'm hoping that if we can automate the negative movement precisely enough, that we can write a script to position the files in Photoshop.

[Peter De Smidt]

Here's a try with Microsoft Ice's "Structured Panorama".

http://i955.photobucket.com/albums/ae37/peterdesmidt/Micro_Ice_Lighthouse.jpg

The repetition was probably caused by the samples not being all the same size. In particular, the second row of samples from the bottom contained about 80% of the row below it, which isn't ideal. (The size of the opening in my negative guide caused this.) I'm hoping that fixing this will solve the problem. If so, it'd be great. Ice is very fast, and it's free!

[Joel Truckenbrod]

I see you beat me to it, Peter. I was assembled them in 5 image horizontal rows (of which the assembly of the bottom 2 rows could be automated through PS, using "reposition image" within Photomerge), and then pieced rows together. As you said, the lack of detail required manual placement for the upper portion of the image. In my opinion that's not a big deal. There still was some color and tonal inconsistency from image to image, though it was better than your first attempt with this negative...not sure of the reasoning, perhaps the RAW editor is imparting some form of minor correction on them? I assume you've completely locked down the settings so it's consistent between files.

Regardless, this all looks extremely promising to me. Thanks so much for doing this!

[Daniel Moore]

Here's a result of letting PTGui find what it can and aligning the sky and upper borders manually while zooming in the detail viewer. Nudging is not easy, can't use the arrow keys, yet.

68858

[Peter De Smidt]

All of the Raw settings were the same. The negative was developed in Pyrocat MC, a staining developer, and so color might vary a bit with density. More importantly, though, it's likely that the flash output varied in both intensity and spectrum, the latter perhaps depending on how hot the flash tube was.

[Cesar Barreto]

When I did a whole exhibition following this method many times I found those issues regarding areas of low contrast boundaries and also I noticed two side effects from digital processing: huge sensibility to flare and inconsistency on Raw processing similar shots. When shooting areas that include negative borders, for instance, I guess the algorithms that rules CR processing render different responses for the whole image and if it happens to be a flat tone, maybe the next frame will be rendered darker or lighter.
Now and then, just in the middle of a row of similar background tones, a single frame turned to be cracked and the stitching functions would show weird effects, like creating sharp borders or rotating the image, importing a piece from somewhere else... and so on.
As I was determined to make my show following this route, that's why I started writing nankim marks on those critical negative areas. It helped a lot Photomerge functions and I guess it offered a solid black curve point for CR processing, allowing more even rendition frame to frame.
Of course, it means a lot more trouble, but from one of those pictures, which turned out to be 100x140cm, I already sold many copies and if I had to make them in the darkroom... wow, that would be a lot of trouble!

[jb7]

It's about as much fun as counting the hairs on your own arm.

That's kinda what I'm afraid of-

Luckily, I've been busy on other things, so I still haven't had any more time to devote to this project.

I think it might be useful if you need more resolution than a V700, or if you haven't got a scanner to begin with, but my initial testing pointed towards the kind of tedium you mentioned. Your results are looking good, tonally, the repeat vignettes seem to have been eliminated- and that is the most obvious noticeable defect I've come across so far.

Good to see that progress is being made; had I been left to my own devices, my lack of progress might have become terminal. My interest might have petered out... (sorry). Your perseverance is inspirational-


j

[Old-N-Feeble]

Don't they make dedicated grayscale digital cameras that have 3x the resolution and no Bayer artifacts?

[Peter De Smidt]

Don't they make dedicated grayscale digital cameras that have 3x the resolution and no Bayer artifacts?

Probably. But they're likely expensive, and we're trying to keep the costs low.

[Mike Anderson]

Don't they make dedicated grayscale digital cameras that have 3x the resolution and no Bayer artifacts?

I don't know, but understand one the goals here (for most of the players I think) is to not require a specialized dedicated digital camera. Then again the camera is a replaceable component in the system, so one could use whatever camera they want.

[Darin Boville]

I don't know, but understand one the goals here (for most of the players I think) is to not require a specialized dedicated digital camera. Then again the camera is a replaceable component in the system, so one could use whatever camera they want.

That would be my hope! I'm planning on using whatever the best camera/lens I already have--thereby reducing the costs of the set up to just the jig or mechanism itself. Costs would be very low in this case :)

--Darin

[Darin Boville]

A thought/concern just occurred to me. Do stitching programs work with monochrome images (including B&W negatives)? I ran into a serious snag in this regard--Autopano Pro, as far as I understand fit, does not.

--Darin

[Peter De Smidt]

I’m creating some new specialized threads for future project development, as this thread has become very long and unwieldy.

The new build threads are:
Camera Supports and Positioning (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7),
Lenses (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7),
Negative Stages (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7),
Light Sources (http://www.largeformatphotography.info/forum/showthread.php?87536-DSLR-Scanner-Light-Sources),
Stitching and Blending of Images (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7),
Cameras and Camera Control Software (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7).
Workflow (http://www.largeformatphotography.info/forum/newthread.php?do=newthread&f=7).

The place to complain about this project is: here (http://www.largeformatphotography.info/forum/showthread.php?87535-DSLR-Scanner-Negativity-post-negative-thoughts-about-the-DIYS-Project-here).

[Peter De Smidt]

Here's a comparison.

The following image comes from a 4000 spi scan on a Screen Cezanne. The full size file would make a print 29.6" x 36" @ 300 dpi with no resizing.

http://i955.photobucket.com/albums/ae37/peterdesmidt/Cezanne_whole.jpg

The follwing image comes from a dslr scanner, using a d200 and a 55mm micro Nikkor f3.5 at f5.6. It was stitched with PTgui. It would make a print 32.3" x 40" at 300 dpi without resizing.

http://i955.photobucket.com/albums/ae37/peterdesmidt/dslr_ptgui.jpg

Here are some screen captures of the files at 100% on my computer screen.

First, the Cezanne:

http://i955.photobucket.com/albums/ae37/peterdesmidt/Lighthouse_Cezanne.jpg

Second, the dslr scanner:

http://i955.photobucket.com/albums/ae37/peterdesmidt/LightHousePTGui.jpg

[Old-N-Feeble]

^^^ Wow... not bad!! Now you've got me thinking I need to buy a really nice DSLR and razor-sharp macro lens.

[ashlee52]

There was a gizmo a few years back where you put the film in a flat holder and shined light through it onto a sensitized piece of paper. This gizmo only used a single light bulb rather than complex tubes or sensors. I wonder if someone could still get one of these to work?

[Old-N-Feeble]

I'd really like to try this with the new Sigma SD1 and a razor sharp 1:1 macro lens. But... I don't have the nearly $3K to spend.

[Ben Syverson]

Great work, Peter!

[Old-N-Feeble]

I wonder if one could use an enlarger to focus the film image on the image sensor of a DSLR laying on its back with the lens removed. That would eliminate the need for a macro lens since the enlarger lens is doing the focusing. Maybe one could rig a sliding platform for the DSLR. I suppose a longer-than-normal enlarging lens may be needed to prevent vignetting by the camera body. This would better align light transmission to the sensor too.

ETA: I should have searched the thread before posting... this was already mentioned way back in post #260.

[Peter De Smidt]

Sure. Plus enlarging lenses tend to make very good macro lenses, especially when reversed. From what I hear, they're best in the 4x - 5x magnification range.

[Old-N-Feeble]

Gosh darn it, Peter. You're gonna force me to sell a bunch of stuff and buy a Sigma SD1. I can build a fixed enlarging setup pretty cheaply/easily out of plain old wood. A really good EL is gonna cost though. For 8x10 film maybe a 450mm? Hey, I could reverse-mount a standard lens like a Nikkor-M and use that as an EL!! Better yet, I have a Rodenstock 240mm Apo-Graphigon that I can use and just enlarge half of an 8x10 at a time.

[Peter De Smidt]

Well, you could certainly do that. Why a Sigma Sd1, though? They're kinda pricey, and the reviews aren't all that good. Why such long lenses?

[Old-N-Feeble]

I only learned of the SD1 today. I've always been fascinated by the Foveon chip and assumed the new one would do miracles. Maybe I'm wrong... I'll research it more.

The reason for the SD1 is its 46MP resolution (equivalent). They are pricey, indeed.

The reason for the longer lens is to eliminate mechanical vignetting at the front of the camera by decreasing acuteness of the angle of light exiting the enlarging lens... but that may not be necessary. A longer lens also makes a straighter light path to the sensor. From what I've read Image sensors very much prefer light to hit them straight-on.

[Peter De Smidt]

Don't let me stop you! By all means give it a try and let us know.

[Old-N-Feeble]

Hey, Peter...

I might just do that. But keep in mind I'm a diseased old car with a V12 running on 4 cylinders these days. I promise nothing but muddy messed up data delivered very untimely.

Mike

[Peter De Smidt]

Hey Mike, that's all that I promise as well!

[marfa boomboom tx]

for those of you with a Coolscan, try this: modify an FH-869s (the 120 holder) by removing the left-hand side bar. That is the side used to tension the film. Remove the screws; lift out the flap. A 4x5 'almost' fits. Luckily the can be "ground" to permit the film to slide into that ground slot. This doesn't interfere with the CS driver, it is those ribs along the right side.

The coolscan thinks you have 120 film in. Scan twice. Paste once. Courage my hearties, courage. Jump. You can always buy another scanner ... :) Well, at least the FH is available from B&H...

later... off to the rodeo

[Ben Syverson]

And if you don't have a Coolscan 8000 or 9000, be prepared to shell out $4000-5000.

To me, that's borderline insane. You can get four drum scanners for that money.

[rdenney]

And if you don't have a Coolscan 8000 or 9000, be prepared to shell out $4000-5000.

To me, that's borderline insane. You can get four drum scanners for that money.

I agree it's insane. But drum scanners are not a replacement for those whose requirements include fitting in a middle-class home, not maintaining an Apple computer museum, or not wanting to fluid-mount negatives.

For those who already have an 8000/9000, however, a scheme for scanning a 4x5 would be slick. But it won't be easy. The scanner stripe runs right down the middle, and I don't know how one scans the entire 4x5 area even with offset mounting of the negative. I'll have to hold a 4x5 negative up to my Nikon holder and see what is really possible.

Rick "who finds stitching slightly rotated tiles challenging, so alignment will be critical" Denney

[marfa boomboom tx]

the size of the modified FH allows a scan of 2.35" and the entire length of the film (5"). The left bar, with a slit, permits the film to ride without hitting anything inside the CScan. There is considerable overlap of scans.

About costs, hmmm... I bought CS back when they weren't hot, nor the only game. So my cost has been $54 for the one "destroyed" holder. It will have to be further refined to manage focus plane etc, but I wanted to know IF. And for $54 and a half hour, I have learned that IF.


later, maybe more.

[marfa boomboom tx]

the size of the modified FH allows a scan of 2.35" and the entire length of the film (5"). The left bar, with a slit, permits the film to ride without hitting anything inside the CScan. There is considerable overlap of scans.

About costs, hmmm... I bought CS back when they weren't hot, nor the only game. So my cost has been $54 for the one "destroyed" holder. It will have to be further refined to manage focus plane etc, but I wanted to know IF. And for $54 and a half hour, I have learned that IF.


later, maybe more.

AND another HOUR and I've learned IT WON'T WORK... DO NOT TRY. save your holder.

The CS left side would have to be loosened and readjusted for the film to travel so the lens could cover and focus the film correctly.

>>>>>>>>>>>> No longer a small mod. <<<<<<<<<<<<<<


The bad thing is I held everyone up for an early start to the Rodeo...

[buggz]

Another link I have found concerning the issues of this method.
<<http://theonlinephotographer.typepad.com/the_online_photographer/2012/01/scan-film-with-camera-1.html>>
<<http://theonlinephotographer.typepad.com/the_online_photographer/2012/01/how-to-scan-film-2.html>>

[Peter De Smidt]

Well, none of that is really surprising.

[Ben Syverson]

This thread would be much improved if people would contribute helpful information rather than theoretical problems or hypothetical stumbling blocks.

Peter has an extremely impressive first start, and it's only going to get better. Already he's shown that he can outclass a Cezanne.

[rdenney]

This thread would be much improved if people would contribute helpful information rather than theoretical problems or hypothetical stumbling blocks.

Peter has an extremely impressive first start, and it's only going to get better. Already he's shown that he can outclass a Cezanne.

There's nothing wrong with theoretical problems and hypothetical stumbling blocks, if they are presented as problems to be considered and overcome. That's not the same thing as saying it won't work, or (worse) saying that it's not worth doing. Those "contributions" are the ones I could do without.

Also, I know the thread is long. But if one is unwilling to read it (and to see that a comment they are offering has already been offered--a couple of times), then it might be best to let it go. And then there's the issue that the discussion has moved on to various sub-threads to discuss each element of the system, despite my misgiving that it has fractured the discussion so that people can no longer find it all in one spot.

I have a status report for my own prototype. My camera mount is now complete. I have secured a long Arca plate that I can use to lock the two standards of my bellows together, plus I have secured a (different) Arca plate that will clamp to the L-plate on my DSLR and be clamped in the Arca clamp on my fine focuser. The fine focuser is a Velmex slide with 1-1/2" of travel, so I need a gross adjustment. I have secured that also: I will use two Incra "t-tracks" intended for precision woodworking, and four clamp bolts. I will secure those tracks to my bed, one on each edge of the base plate on which the fine focuser is mounted, and use two thumbscrew clamps to hold the base plate to the two tracks at the desired position. The clamps have a bit of play when loose, so I'll include an alignment guide for the edge of the plate to ensure alignment when tightened. This adjustability will make it easier to place with lenses of much different focal length--my target range is 50-135mm lenses used at 1:1.

As previously reported, my negatives stage is assembled and ready to be mounted.

Finally, I have secured the mounting surface. I'm using a Phenolic-coated 3/4" plywood tool base. These are intended as precision work surfaces for fine wood-working. The plywood is something like 10 plies of very thin birch veneer, with a polished phenolic resin finish on each side. The surface is quite hard, but can still be drilled for mounting screws. If the plywood panel is held flat, the surface will be flat. To hold the panel flat, I will mount the plywood to the top of a polished granite sink cutout, using appropriately placed anchor bolts tightened to prevent vertical movement but not to prevent horizontal expansion of the wood. That will prevent the two materials from attempting to warp each other in case of unequal expansion and contraction. The diamond bits I need for the anchor bolts on the granite have been secured. (I bought them to drill holes in ceramic tile for a bathroom refresh that, em, altered my priorities for the last couple of weekends, but in the end didn't need them for that project. I had to have them, though--that's my story and I'm sticking to it.)

I'm down to a couple of hours of directed effort and I can begin my own testing. I'll post new pictures when I'm done with assembly.

On the stitching front--as I have reported in the stitching thread, I have thrown the stitching automation problem over to some students of a friend of mine who specializes in this sort of thing. They might come up with a reasonably well-automated approach to stitching using ImageJ.

Is any of this practical? Probably not while good scanners are still available. But I predict a time when all of us will be building, or paying someone to build, something similar that uses a digital imager that is available, rather than by creating a digital imager implementation that cannot be supported by the broader market. It's certainly not cheap. At OEM prices, what I've constructed would cost about $1000 in materials, plus labor and overhead, plus design, plus some sort of enclosure, plus the light source, plus the DSLR. If what we end up with turns out as good as current high-end scanners, it won't be because they are cheaper, especially for those unwilling to use the materials and hand and build it themselves. At retail using new stuff (and including the DSLR and lenses), what I've constructed would probably have to be sold for $10,000 or more. And with the granite base it will weigh about 100 pounds--it won't be any lighter than those drum scanners that require people to add onto their house and hire a crew of native bearers.

Rick "whose design will double as a high-end photo-macrography station" Denney

[Peter De Smidt]

Rick, I'm glad to hear about your progress. It'll be exciting to see the system when it's put together.

I'm planning on using my system for regular macro photography as well.

Regarding affordability and feasibility, I agree that our rigs would be fairly expensive to make. That said, I built my prototype to be big enough to investigate a bunch of different things, including use with 5x7 negatives, lots of lens experimentation... If someone knew exactly what they want to do, say use a particular lens to scan particular size negatives, there could be a lot of simplification.

Regarding splitting up the discussion, I did so in the hope that people with knowledge on various things, e.g. software, robotics..., might chip in if they didn't have to wade through 50 pages of forum posts before commenting. As usual, though, there's pluses and minuses to each option.

[Laron]

/ I would just quickly thank you guys very much for sharing your experiences, Im also super interested in what you are doing and definetely subscribed to this thread!
the comparison image speaks for itself! would be great to see your rigs as well. cant wait to build mine once...

[Donald Miller]

I have followed this thread with interest. There is a lot of good information contained here. I have a question that I don't have the answer to. For that reason I am posing it here. I have a Canon 65mm dedicated macro lens. This is the lens that can not be used for normal pictorial use (macro only) and will render at 1X up to 5X magnification. How would this degree of magnification compare to a drum scan? A good educated guess of the comparison will determine if I go forward to design a system to use that lens in a scan capacity with either my 5D MkII or 1DS Mk III. I have a Novoflex Cross Q focusing rail for two axis (X and Z) that I would like to incorporate. My other problem, should I decide to go forward with this, would be the third (y)axis. Thanks for sharing your thoughts on this.

I will also post this in the lens section related to this topic...moderators please choose the proper classification.

[Peter De Smidt]

Donald, I commented on your post in the other thread.

[Peter De Smidt]

I'm going to take an extended sabbatical from this project. I have other more pressing matters to attend to. It looks like others have this project well-in-hand, and I leave it to them.

[Mike Anderson]

I'm going to take an extended sabbatical from this project. I have other more pressing matters to attend to. It looks like others have this project well-in-hand, and I leave it to them.

Well I think your achievements so far are impressive and it's been fun and interesting to watch. Enjoy your break.

[jb7]

Peter- you deserve a rest- you've been driving this thing for a long time, and the results are looking good.

It's nearly time for me to dust off my apparatus, which was substantially completed by the end of January, according to the exif on the pictures I took to record the process-

I did some tests at the time, but I was getting a lot of vignetting, and I need to revisit it, and try to sort it out.

John, in NYC, the thing I built will easily take the larger negative, up to 11x14, or 12x20-
However, as soon as I had it built, I wished I had made a dinky little 4x5 version.

That's the MKII, and it's on the drawing board, along with countless other projects-

[oysteroid]

This is an interesting thread. I didn't read it all, so I hope this hasn't been mentioned already. Anyway, a while back, I was researching this whole thing and after looking at everything I could find online in the way of tests, I came to the conclusion that of all the common macro lenses for DSLRs in the 60-105mm range, the Sigma 70mm f/2.8 Macro had the best sharpness from corner to corner and seems to be quite free of distortion. I never did make the purchase though, so I haven't tested it in this application. But it is an option worth looking at I think. Coupled with one of the Sony 24MP APS-C sensors, it seems that a lot of detail could be recorded. One caveat though, as I seem to remember reading that Sigma has some quality control issues and that performance of these lenses varies quite a bit from sample to sample. So if you buy one and it isn't so great, don't blame me!

[Peter De Smidt]

http://www.gigapan.org/gigapans/64451

[Mike Anderson]

http://www.gigapan.org/gigapans/64451

Interesting. More info (http://www.smallworldexplorations.com/micro_gigapan_technology.php).

Looks like they're doing automated focus stacking and stitching.

[Peter De Smidt]

Here's a link on digitizing 16mm film. http://www.pc-control.co.uk/film-digitiser.htm

[Struan Gray]

I'm coming to this a bit late, but have a few pointers that might be of interest.

Here's how to do the job properly: http://hea-www.harvard.edu/DASCH/scanner.php

This was a scanner built to digitise astronomical glass plates, with stringent requirements for spatial and densitometric calibration, and with a high throughput. The technical paper linked from that page is worth reading, and the video is fun to watch (and dream about). I don't know what the whole setup cost, but some points are worth noting for a homebrew effort.

First, and I don't think anyone has mentioned this yet, a telecentric lens helps solve many issues. It pretty well eliminates vignetting, and it ensures that the digital image of the film always has the same magnification even if the negative is bowed in the holder. I haven't done detailed calculations yet, but it's probable that at 1:1 imaging you can eliminate refocussing altogether.

There are commercially available telecentric lenses with the right characteristics, but most of them are incredibly expensive by homebrew standards. The insect focus stackers seem to like the Cosmicar 55 mm, which is a C-mount lens but covers well enough at 1:1 or more. It is also possible to jury-rig your own telecentric aperture for a regular macro lens - see this discussion on a macro forum - and it's linked threads - for some ideas

http://www.photomacrography.net/forum/viewtopic.php?t=1032

The second point is that eliminating spatial patterns with repeats equal to the step-size of the scanner is always hard, even with the best equipment. If you don't have the option of detailed calibration (and temperature control to keep the calibration constant) the best solution is to take photos on a finer grid - the redundancy helps with blending. The limiting case of this would be to take a video of the film scanning continuously under the camera (a technique used in spectral detectors for nulling out the small variations in response from pixel to pixel) but I suspect you'd lose resolution that way.

The third point, is that film handling, cleaning, loading and unloading, and writing the catalogue entries will take as much time, if not more, than making the scan. It makes sense to have more than one negative holder or scanning platen so that you can be loading a second sheet while the first is scanning. This, more than the bragging rights of a robot stage, is why I would regard automated movement - on one axis at least - as essential.

I applaud the efforts of those who have actually tried this for real. At the moment my investigations are at the stage of working with my daughter and her Lego Mindstorms kit on a scanning table, and tinkering with the lenses I have in the house to see if I can get a workable telecentric lens arrangment without having to spring for a megabuck macro lens.

[Peter De Smidt]

Hi Struan,

Good stuff. Thanks for posting.

[peter ramm]

Straun, thanks for posting the link. I love weird and wonderful systems. Wonder if Harvard actually ended up using it for the specified project. What often happens with things like this is that a grad student or post-doc puts something together as a feasibility study, publishes it (and uses it for an academic requirement) and then the results of that experience are used to work with a commercial supplier who can provide something that will do the job with minimum fuss. They have a lot of plates to truck through. Do you know the outcome here?

Couple of comments. Telecentricity at the field lens is not required for film. However, it is useful at the detector plane because tele lenses can have some strange color aberrations. We built a singly telecentric lens that worked great in monochrome (what it was designed for) but multiwavelength imaging took some careful calibration and was never really aberration-free.

Yes, the optics tend to be huge. One reason is that the greater the reduction factor the more aberration and deviation from true telecentricity - so the lens becomes more like a pipe. Sill has done well with its lenses and they are used in a lot of deep imaging applications (e.g. microwell plates, machine parts).

Note that telecentric lenses are not immune to vignetting. They collect rays in parallel at the field lens, but the efficiency of collection varies from point to point. Also, any lens design is a compromise. Telecentric lenses are designed for measurement (low distortion), not optimal modulation transfer. You can get reasonable MTF out of one of these but the tolerances become difficult (= even more expensive).

Wow, that is quite a sample movement system. Fun to build if you have the budget.

[Nathan Potter]

I believe Struan is referring to the Depth of Field advantage of a telecentric setup. The entrance pupil is located essentially at infinity by placing an auxillary stop at (or near) the exit pupil of the macro imaging lens. The auxiliary stop, in effect, selects mostly on axis rays exiting the main lens rendering the selected rays from the subject to near infinity corrected and thus providing hugh depth of field. Cute stuff but of course with sacrifices. The biggest disadvantage for scanning is much reduced FOV (Field Of View) due to restricting the diameter of the entrance pupil.

The reduced FOV is less significant for the stepped macro folks because their subjects are tiny to begin with, so this is a neat application for that endeavor and provides near zero perspective distortion when scanning through the desired depth. Increasing the field of view requires increasing the physical diameter of the imaging lens. Restricting the effective aperture also will reduce the resolution of the imaging lens due to diffraction. As always there are optical tradeoffs.

Peter, I hadn't thought about the advantages in reducing chromatic distortions but seems that could be quite significant.

All interesting stuff indeed. Thanks Struan.

Nate Potter, Austin TX.

[jb7]

Ingenious stuff- however, if I had to employ an Ivy League University research department, develop a custom telecentric lens, ccd, and lighting system, crane in a 2,4000lb linear stage, and then have to consider the project a failure if I couldn't hit the target of scanning one 8x12" plate per minute, well, I might just have to stick with the V750. At least I wouldn't have to upgrade my current air conditioning system- which reminds me, those windows could do with a clean...

I think there's a danger with over-complicating things. It's fine if you're NASA, or have access to a large budget and/or unlimited time, but problems don't have to be that daunting. If something isn't working, it's often more productive to scrap the idea and move onto the next one. Maybe with less moving parts...

Even the Telecentric lens, it's a solution to a problem that may not exist. True, for the project you mention, which uses a 46mm ccd, it was probably vital, but using a DSLR instead, makes it less so.

Regarding the robotic stage- again, I don't think it's essential, though I suppose that depends on the amount of scanning you might have to get through. If you were the Astronomy Department at Yale, and you had to scan your entire back catalogue of plates, then yes, you have a point- but speaking personally, I might spend more time making the robotic stage than I would spend scanning pictures I need to reproduce at five foot high.

I'm torn between reading your post as an actual indication of what you think is necessary to make a scan with a DSLR, or if perhaps you have your tongue firmly in your cheek-

I'm slightly reminded of the alleged $10 million that was spent developing the Space Pen, while the Russians went up with a pencil...

[jb7]

I hope someone can prove me wrong regarding the Telecentric lens, maybe someone already has the equipment lying around, and can test to find an ideal setup- but it sounds like quite an involved project in itself...

[Peter De Smidt]

The gigamacro system works at up to 5x magnification. They don't use a telecentric lens, and they seem to get pretty good results.

I agree with Jacob that automation is unnecessary. If you aren't doing lots of scans, or working at magnifications above 1x, it's a simple enough matter to slide the negative carrier from place to place using a guide. That's what I did for the lighthouse picture, and it works fine.

That said, I'd like to automate the stage, not only because it might help with stitching difficult negatives but, well, it's fun.

I appreciate new suggestions, even esoteric ones. Some of it might be beneficial down the road. Right now I'm still working on the basics.

[Struan Gray]

Joseph, I hope neither you nor anybody else feels that I'm slighting your efforts. Linking the Harvard plate scanner was a way of showing that the engineering can be taken to a level that rivals or surpasses drum scanners.

In fact, once you see the trouble and expense you need to go to to get true micron-level positioning and repeatability it becomes abundantly clear that a homebrew setup needs to use software compensation for inaccuracies in positioning or angle setting. I have used stages like the one shown here in various forms of scientific instrumentation, and they simplify all sorts of calibration and positioning issues, but they are in no way simple or cheap.

Peter, the Harvard system has been churning out scans for a while now. The project status page says they are up over 21 000 scans, so it's not just tinkering. I still think it's amusing that one of the most stringent design goals was the ability to get the thing into the building :-)

Telecentric lenses are not a universal cure, but they do simplify some of the issues that crop up in stitching. The benefits are greater if you are measuring 3D objects, but I can see enough reasons to see if I can roll my own. A film scanner is going to be working at photomacrography repro ratios, so there's enough space to put auxiliary apertures into the light path.

With a lens on an extension bellows (or your DSLR mounted on your LF camera) going telecentric can be as easy as adding an aperture at the focal plane of the lens you would be using anyway. Worth a try, at least if you like tinkering. More complex but also more versatile is to add an auxiliary lens in front of your regular one, which is a variant on the old macro trick of reversing a normal lens in front of a short telephoto but with a spacer between the two lenses (again, an LF camera works well here). John Hallmén is a Swedish photographer specialising in insect macros who has got good results out of the Computar lens I linked, which costs a couple of hundred dollars. That might seem pricey, but it's comparable to, say, custom machining if you need to make lens mounts and other gadgets.

http://www.flickr.com/people/johnhallmen/

FWIW, a telecentric doesn't have more depth of field than an equivalent normal lens. There is a subtle effect if you modify an existing lens with an external aperture because you will almost certainly change the pupillary magnification, but that's not what I meant in my original post. The advantages for this application come from the projection geometry - you get constant magnification of the negative even if it shifts a bit towards or away from the lens. Telecentrics can still have distortion (although lenses built as telecentrics tend to be designed for low distortion at macro repro ratios) and because distortion can vary if you move the aperture around in a lens design the homebrew methods can in principle make distortion worse.

The form of telecentrics I am interested in are the ones with two lenses placed back to back with an aperture in between. If the front lens is reversed you find yourself needing two lenses which are sharp at infinity rather than one which is sharp at macro ratios. For me, the former is easier and cheaper to arrange. The lens closest to the object/film needs to be physically large, but for an APS-C camera the Kowa and Hasselblad MF lenses I have lying about anyway will be more than adequate. Another possible advantage is that the telecentricity is fairly robust if the two lenses are not perfectly aligned (with the resolution requirements of this project at least) so it may prove possible to compensate for changes in the film height by letting the camera autofocus the rear lens.

Of course, as an inveterate lens tinkerer I have several APO-ronars lying about too. It will be interesting to see how much combinations of MF and 135 lenses compare with an existing lens designed for low distortion and 1:1 imaging. My hope is that the homebrew solutions will allow for larger apertures, but a face off is one of the things I intend to test.

[jb7]

Thanks Struan, and thanks for your comment elsewhere-

No, no slight taken- the scanner you linked to has very demanding accuracy and performance criteria, and I'm not sure how any of it would translate to a kitchen table version. It might have exactly the level of precision necessary in order to make meaningful astronomical measurements and calculations, but I don't think anyone is going to be measuring the distance between my dust particles. (except, perhaps, for PTGui) I think that if this thing is going to work for scanning photographic images, it has to be a simple and achievable design, and there's a chance that someone might be put off starting a project like this if they're told that it's impossible from the outset, without hugely expensive optics and control systems.

True, there might be some trickle down technology, your post is the first in this discussion that has mentioned telecentricity, for example- and I hope someone follows up on that and can cobble together something that works- but minimizing the depth of field necessary to photograph a piece of film might be achieved in other ways too. If it turns out that I can connect a couple of Zuiko primes to perform that function, then I'll be very happy to spend the €5 on the connecting ring. I'd be less happy to spend large amounts of cash on optics if they were to be useless for any other purpose, and if there was a good chance that the first few attempts wouldn't produce usable results at all. I think I might just be happier buying a Micro Nikkor, and taping the transparency down...

I think the difficulties with a normal lens are field curvature- which the telecentric lens might inherently cure? Distortion? Would positioning an external aperture in the right position remove distortion from a lens that already exhibited it? And evenness of illumination, would it cure that, or might some of the falloff be due to the inefficiencies of the sensor in dealing with off axis rays?

I'm not for a minute saying that we shouldn't be having this discussion, you never know where ideas will come from, and all input is valuable in that regard- but I do think simplicity and accessibility are key qualities that shouldn't be needlessly circumvented-

[Struan Gray]

If it turns out that I can connect a couple of Zuiko primes to perform that function, then I'll be very happy to spend the €5 on the connecting ring. I'd be less happy to spend large amounts of cash on optics if they were to be useless for any other purpose, and if there was a good chance that the first few attempts wouldn't produce usable results at all. I think I might just be happier buying a Micro Nikkor, and taping the transparency down...

I'm in complete agreement with this philosophy.


Mind you, there is a certain 'whoa!' quotient in having a lens that looks like this: Xenoplan on ebay (http://www.ebay.com/itm/SCHNIEIDER-XENOPLAN-1-3-C-MOUNT-LENS-BILATERAL-TELECENTRIC-/330679848696)

[jb7]

'Whoa' - is right-

I've come across a less spectacular version- http://www.ccddirect.com/store/customer/product.php?productid=17435

However, from what I've read, these lenses don't project a very large image circle-
though presumably coverage would increase in the close up region-
I suppose if this lens covered its native format at infinity, then there wouldn't be a problem at all.

Perhaps we shouldn't be looking at using a DSLR in the first place, micro 4/3rds seems to be the native format for this- though 1:1 might produce even more frames than I've used on mine already.

A lesser issue is the Flange Focal Distance, which is much shorter than Nikon's- however, again, for close up, this shouldn't be a problem-

An issue which I'd have no idea about, without having access to the lens, and a little screwdriver, would be remounting this in an F mount.
I do have access to one of those lenses here, for not very much money, but I have to get out of the habit of buying lenses...


btw, if you'd like another Whoa, check out the thread about pictures of photographers with their cameras in a couple of minutes...

[jb7]

Ah- I've just looked up the specifications of that Computar- 11mm ic, presumably at infinity. So, 22mm at 1:1.
Might be just possible on a crop sensor, but I really wanted to use the full dynamic range of the D700.
I don't think this is going to be easy...

[Struan Gray]

Lenses can be telecentric on the object side, which gives you the constant magnification and eliminates parallax. Or they can be telecentric on the image side, which for regular photography is usually presented as a way to get the light square on to the sensor. Or they can be telecentric on both sides, like the Xenoplan.

One advantage of a bilateral telecentric for our application is that the images they produce are less sensitive to tilts or misplacements of the object, lens or sensor. This technical brief from Schneider has more details than most will want to know:

http://www.schneiderkreuznach.com/pdf/div/optical_measurement_techniques_with_telecentric_lenses.pdf

The ones that are bilateral are usually specced for a fixed repro ratio and working distance (distance from front lens to object). The good ones *only* work well under these conditions and perform poorly or not at all at other magnifications and distances. For example, a pure bilateral telecentric optic is actually afocal for infinity light - it does not focus it at all, but simply expands or contracts the parallel beam. It's more like a rifle sight than a photographic lens.

So you have to be careful with eBay oddballs (even if they do look supremely cool :-). This Xenoplan lens will surely perform very well on the intended format, but that's quite a bit smaller than FF 35 mm and there is no guaranteed way to make it cover a larger sensor except for turning it round and taking pictures at 3:1 instead of 1:3. There is probably some wiggle room, but you would need to have the actual lens for testing, or a conversation with the Schneider application engineers, to know for sure.

[rdenney]

So, what about long, fast medium-format lenses? I have a Pentax 200/4 that covers 6x7 and a CZJ Sonnar 180/2.8 that covers at least that. Is the idea that these could be arranged nose to nose with a stop in between them? That's sort of an inside-out Super Angulon, which is really a pair of reversed telephotos arranged tail to tail. Something about the concept is not clicking in my brain.

Rick "noting the large exit pupil of these lenses" Denney

[peter ramm]

Straun, the Harvard system is a rara avis. Good for them. I've seen so many one-offs sitting in back rooms and ultimately cannibalized for parts.

Given the level of expertise that participants here are showing, why not think outside the camera box a bit? Sure, working up a flying spot or rail-driven PMT would be a project but linear arrays are simple and reasonably priced. Is there anyone here with the skill to replace the crappy array/lens element in an existing Epson with a better one? You'd wind up with something like one of the higher performance flat beds. This is very much a question, not a suggestion. I do not have any expertise in this type of integration. Everything we did was with cameras - which is why I distrust them.

[Peter De Smidt]

And you can still buy them new. See: http://www.edmundoptics.com/products/displayproduct.cfm?productid=2904
They do have pretty impressive effective apertures. I have a Mitutoyo 2x infinity objective, but it's effective aperture at 2x is 18, for instance, and a Rodagon D would have an effective aperture of 11 at 1:1.
But the Schneiders are only meant to cover a 1/2" sensor, which isn't ideal. Plus mounting that thing with a c-mount seems a bit silly. It would definitely have to be braced.
Scitex, Screen and Imacon didn't use telecentric lenses for their scanners, (I have some of them) but perhaps it was simply for cost reasons.
I'll be very interested to see what Struan comes up with.

Note that there are two Linos machine inspection lenses that are supposed to be better than the Rodagon Ds. See: http://tinyurl.com/72un7ra.
But, just because I know that Joseph is watching, a reversed Nikon 55mm P Nikkor gives very good performance, including low distortion, and they're inexpensive and useful for other things.

[Peter De Smidt]

Peter, can you point us to the type of linear sensors that you are suggesting?

I'm curious, though, as to why you think we won't accomplish our goal with a dslr. We've had three people run tests now, all with non-optimized systems, and in each case the dslr setups have out-performed an Epson, and in some cases out-performed a Cezanne in some respects. With better lenses and light blocking we ought to be able to do even better.
In addition the gigamacro people are using a dslr to do some pretty impressive stuff. See: http://gigamacro.com/2011/film-grain-test-3-3-gigapixel-macro-photograph/ And that's with a lens, the Canon 65mm, that we can easily do better than at 1:1 magnification. Plus, there's the huge advantage of being able to use your dslr to take pictures in situations where you don't want to use your film cameras. (For instance, I photograph a lot of indoor judo matches, a situation certainly not suited to LF photography.) So what's the problem again?

[Nathan Potter]

As Struan points out I inaccurately suggested that there was a depth of field advantage to a telecentric setup. The advantage is in the constant magnification ratio achievable while varying the object to lens distance. This property ostensibly allows for more error free and faster stitching of individual frames. Although it appears that restricting off axis rays by use of a supplementary aperture would lead to some increase in of DOF at a cost of resolution. The equivalent NA of the system will decrease.

Nate Potter, Austin TX.

[peter ramm]

Peter, can you point us to the type of linear sensors that you are suggesting?

I'm curious, though, as to why you think we won't accomplish our goal with a dslr. We've had three people run tests now, all with non-optimized systems, and in each case the dslr setups have out-performed an Epson, and in some cases out-performed a Cezanne in some respects. With better lenses and light blocking we ought to be able to do even better.
In addition the gigamacro people are using a dslr to do some pretty impressive stuff. See: http://gigamacro.com/2011/film-grain-test-3-3-gigapixel-macro-photograph/ And that's with a lens, the Canon 65mm, that we can easily do better than at 1:1 magnification. Plus, there's the huge advantage of being able to use your dslr to take pictures in situations where you don't want to use your film cameras. (For instance, I photograph a lot of indoor judo matches, a situation certainly not suited to LF photography.) So what's the problem again?

Peter, I think this is the package that Epson is using. Next step would to contact suppliers like Dalsa, Kodak, Fairchild etc. and get suggestions. Not my area of expertise but there are other savvy people here. Ideally, you would get something with better optical performance that can be inserted into the Epson mechanism.

http://pdf1.alldatasheet.com/datasheet-pdf/view/164899/NEC/UPD8870.html

As to commenting, my viewpoint is based on experience, but it is still only my own view. I don't want to discourage anyone elses' views and I really want you to succeed. I would love to turf my Epson. That said, i believe a DSLR scanner will easily best the resolution of an Epson, that its dmax will be less - though the Epson is pretty crappy as well - and that the the work needed to do even small plates (4 x 5) will mean the systems that are built will not always get used. However, the ability to get really high resolution scans from low cost equipment may be enough to justify the work for some. YMMV

If this were LULA or some other digital site, I might be more optimistic. However, people shoot LF because they love the look of film - at least I think that's why. That look is subtle, with its own set of artifacts and peculiarities. Just think how obsessed we get with how a lens "draws". Replicating that sort of thing takes a pretty good scanning system - with tonality as its primary criterion. I haven't seen anything camera-based that rings my bell, and that includes systems like Gigamacro.

[Peter De Smidt]

Peter,

Thank you for the explanation. In my scans of bw film, I haven't noticed a problem with dmax, but that could be a completely different story with something like Velvia. It's true that HDR techniques can significantly increase dmax, as demonstrated in a test presented earlier in the thread, but that's at the cost of double (or more) the exposures of an already exposure happy system.

I'm curious about the real range of information required when talking about high res scans of bw film.

An online guru recently said, "Film has so much noise (grain) that it's self-dithering, meaning that at high resolutions, bit depth is almost completely irrelevant." I don't know if that is true, or even germane, but it sounds like it might be.

In any case with a project like this I'm a try-it-and-see type of guy.

[rdenney]

An online guru recently said, "Film has so much noise (grain) that it's self-dithering, meaning that at high resolutions, bit depth is almost completely irrelevant." I don't know if that is true, or even germane, but it sounds like it might be.

This has been demonstrated even on this forum, I think by Ben Syverson, pretty persuasively.

But that means we have to scan at high enough resolution to resolve the grains, and not just to notice that grain exists. I don't think I'm going to be able to do that with my 5D at 1:1. Maybe it's possible with a sensor that has much higher sensel density. Of course, going to higher magnifications make a lot of things work better except for the level of effort.

Rick "still pondering a collimated light source" Denney

[Ben Syverson]

Rick, your 5D at 1:1 will resolve grain, just not as finely as some of the newer cameras. It should be enough to break up any banding, so I don't think you'd see any benefit from processing in 16 bit...

[Old-N-Feeble]

All these possibilities keep swimming around in my mind... what's left of it. We could spends many thousands of dollars on either a good drum scanner or this proposed DSLR method. For me, and I suspect for most of us, its viability balances on cost and complexity. But the OP and most others already alluded to that.

Being the spoiled brat that I am... I want the best... but I'm also unwealthy and stoopid. So, I'll be settling on something middle-of-the-road. I'm watching these related threads with great interest and anticipation. I know that many very good options will be developed by several people. I'm hoping to avoid spending $2K on a DSLR with enough resolution to make this method really shine. If I had to though... at least I could use it as a DSLR too. :)

[Peter De Smidt]

This is a 4x section of Acros developed in Pyrocat-MC taken with a D200 and a 4x microscope objective.
http://i955.photobucket.com/albums/ae37/peterdesmidt/sc_100.jpg

Is that large enough grain to have the effect we're discussing?
What if any implications does film's self-dithering quality have for our project?

[peter ramm]

Interesting observation Peter and Rick. Indeed, film has no set bit depth. It is dependent upon the RMS noise present in the sampling window. Over a small distance, grain becomes dominant and a few more exposed grains in one area will yield a very different value than in an adjacent area. SNR is lousy. Pull back a bit and film becomes very precise.

We used to make calibrated measurements from grainy radiographic film. Over small areas (e.g. 1 mm2) you might get only 6-8 bits precision, but one can get a true 10 bits out of a well processed film if you measure areas larger than about 1 cm2. Of course, film only responds well within its linear range. As soon as you get into the tails of the distribution bit depth compresses pretty quickly. Our eyes are tolerant of that. Quantitative systems are not.

I realize that measurement has nothing to do with photography. I guess the question there is whether it is necessary to resolve grain to archive a neg, given that you just going to be viewing it. I don't think anyone really cares about the grains. They are just an indication that the MTF of the system is clean enough to render non-granular detail well. You do see that in the print and it is the area that the DSLR will really excel in - relative to the Epson.

[Struan Gray]

So, what about long, fast medium-format lenses? I have a Pentax 200/4 that covers 6x7 and a CZJ Sonnar 180/2.8 that covers at least that. Is the idea that these could be arranged nose to nose with a stop in between them? That's sort of an inside-out Super Angulon, which is really a pair of reversed telephotos arranged tail to tail. Something about the concept is not clicking in my brain.

Using MF optics on smaller formats will help considerably with evenness of illumination - assuming that you can control flare from the non image forming light. The purpose here is more subtle - to find lenses with the right focal length but large front elements. Before anyone queries that, I hold up as evidence my 50 mm f2.8 for the Pentax 110 camera and my 50 mm f2.8 for Hasselblad 2000 series. The change in lens design widens the field and enlarges the elements.

For the deep side canyon into which I seem to have dragged this thread, the point is that a telecentric lens needs to have a front element which is a little bit larger than the thing it is trying to photograph. MF lenses generally have physically larger front elements for the same focal length compared to 35 mm lenses, so they are useful candidates for the front of a homebrew telecentric. An Aero Ektar is another candidate if you want large field sizes.

You can't just reverse one lens and put it on the other. You'll need a tube of some sort. Telephotos for SLRs have an additional problem that the nodal points may be badly placed - for example, most of them won't work as a simple macro with a reversing ring to mount them on the camera because the front focal plane is way out in front of the lens, so when you turn it round it ends up behind the film/sensor and you can't focus on anything at all.

I should probably move this lens-only discussion to the DIY lens thread, but I'd really like to tinker a bit with my lenses first so I have some experience to relate as well as speculation. In brief though, you could use two of your MF SLR lenses with a male-male thread coupler. Macro users know that if you mount one lens on another the repro ratio is just the ratio of the focal lengths. 50 mm reversed on a 150 gives you 3:1. To make the system telecentric you move the 50 mm outwards on a tube, bellows, or similar. The first telecentric setup is when the front lens produces an image at infinity of the aperture of the rear lens. With thin lenses that means it's 50 mm away. With thick telephotos the distance will be greater. The second telecentric setup is when the rear focal plane of the front lens (what was the front focal plane before you reversed it) coincides with the front focal plane of the second. Place a stop on this plane and you become bilaterally telecentric. The magnification remains at 3:1 the whole time.

[Struan Gray]

Grain aliasing exists, and can make grain look larger than it really is. The signature is that it goes away if you digitise on a finer pitch. Kodachrome 200 is a good film for testing because it has large, sharp-edged grain. The apparent grain gets worse and then better again as you change the pixel spacing - in this case, the repro-ratio of your images.


PS: resolving or detecting grain is one thing. Stitching so that the grain lines up is another - and probably too ambitious for all but the most megabuck projects.

[jb7]

I'd have to agree with this-
The stitching on my first test is really imperceptible-
However, if had resolved into the grain, I'm quite sure that the grain would have broken down at the stitch junctions, and would have been noticeable for at least some of the scan, and possibly on every join.

Lighting has a big influence on how the grains are resolved too-
I think I might try to diffuse my source for the next scan-

[Ben Syverson]

Is that large enough grain to have the effect we're discussing?
Oh definitely. You don't even need to go that far.

The upshot is that we can do 100% of our processing at 8 bit versus 16 bit. 16 bit is overkill if you can see any kind of grain texture.

[Peter De Smidt]

Getting back to the telecentric idea. Wouldn't this only be helpful if one employs focus stacking, since the whole point seems to be keeping the subject the same size when changing focus? If we don't change focus during the scan, then my very cursory understanding of the idea is that there wouldn't be any benefit. Is that correct?

[rdenney]

Getting back to the telecentric idea. Wouldn't this only be helpful if one employs focus stacking, since the whole point seems to be keeping the subject the same size when changing focus? If we don't change focus during the scan, then my very cursory understanding of the idea is that there wouldn't be any benefit. Is that correct?

I think it would also be helpful to correct any subtle misalignments in the negative. If one side of the negative is slightly further away than the other side, it will be subject to less magnification than when it's on the other end for the next tile. Those misalignments might result from negative curvature.

Let's do some math to see if it's an issue:

I have measure a maximum curvature in my holder of 0.3mm in the center of the frame. That is actually not bad, according to what others have said. Assuming (conservatively, since the scan frame doesn't at all cover the whole range of curvature) that this is the maximum error, one end might be 0.3mm further from the camera than the other end. Let's assume 1:1 target magnification with a 100mm focal length. At 1:1, the film should be 100mm in front of the lens's rear node (I think I have that right). So, a 0.3mm error means that one end of the negative being scanned will be 0.3% farther from the node than the other end. And the project size of the negative will therefore be 0.3% smaller, using similar triangles. That's 8.7 pixels across the width of my Canon's sensor, and it has big pixels. A telecentric lens, because the magnification does not change, would eliminate that problem altogether.

Or, let's say the negative stage is out of square with the camera by 2 thousandths across the width of the 4x5 frame. 0.002" = 0.05mm, and one 36mm-wide frame might encompass half of that. That error is smaller than film curvature. If one side of the frame is 100.03mm from the node (along the parallel line, of course) while the axial distance is 100.00mm, then that's a 0.03% error. That means the negative on that end will be 0.03% smaller than when it's on the other end. 0.03% of my 2900 pixels is about a pixel. In that case, it's okay. Getting the negative square within 0.002" of the camera is no minor task, however.

Since I don't have a telecentric lens, I'm hoping my calculation above is conservative enough to render it not important, or that it can be corrected easily in practice. I haven't gotten there yet.

Rick "correcting focus but moving the camera for each frame might solve the problem, but create others" Denney

[Struan Gray]

I've been tinkering. I'll post in the lenses thread when I have some real numbers, but FWIW and IMHO, here are some qualitative experiences.


1) Dan Fromm knows what he's talking about when it comes to photomacrography. I'm surprised he hadn't yet told us all to stop messing about and read the Lefkowitz book.

2) There are no free lunches. And you can't make a silk purse out of a sow's ear. If you want real quality, suck it up and buy a real macro lens.

3) Many of the manual focus 70s-80s era primes I have at my disposal have their entrance pupils quite deeply recessed behind the front of the lens barrel. Quite often a simple stacking arrangement is already close to telecentric on the object side.

4) In particular, two stacked Pentax 50 mm f1.7 lenses work very well at 1:1. (but my DSLR is only 6 mpix, so I'm aiming for 2:1 :-).

5) Stacked MF lenses give a lovely even illumination. Distortion can be surprisingly high though, even with Zeiss/Hasselblad primes. [a side discovery: my orphaned Kowa lenses might make good candidates for telecentric Kohler illumination, even if they are not worth the hassle as taking lenses].

6) An arrangement which is telecentric on both the object and the image sides is going to have a long tube length.

7) Telecentric arrangements need careful alignment, particularly for angles. Any working setup will need to be locked down and left alone.


That seems like a bunch of negatives, but it's really a narrowing of parameter space to the point where I can ask some real questions. I've been cobbling together ways of mounting lenses, cameras and apertures on my Sinar's rail, so if I'm not hiding eggs round the garden the entire time, I'll see if I can take some test shots over the Easter weekend.

[Peter De Smidt]

Struan, what Lefkowitz book?

[Struan Gray]

Lester Lefkowitz, "The Manual of Close-up Photography"

On Amazon here: http://www.amazon.com/Manual-Close-up-Photography-Lester-Lefkowitz/dp/0817421300/

[Peter De Smidt]

Here's and article on DSLR film scanning: http://www.thedambook.com/downloads/Camera_Scanning_Krogh.pdf

[Dan Fromm]

Dan Fromm knows what he's talking about when it comes to photomacrography. I'm surprised he hadn't yet told us all to stop messing about and read the Lefkowitz book.

Y'all are having too much fun to be bothered. If you look at Lefkowitz, you might also want to look at:

Gibson, H. Lou. Close-Up Photography and Photomacrography. 1970. Publication N-16. Eastman Kodak Co. Rochester, NY. 98+95+6 pp. The two sections were published separately as Kodak Publications N-12A and N-12B respectively. Republished in 1977 with changes and without the 6 page analytic supplement, which was published separately as Kodak Publication N-15. 1977 edition is ISBN 0-87985-206-2.

Gibson is very strong on lighting, exposure, and on what can and cannot be accomplished. His books, although relatively weak on getting the magnification with lenses made for modern SLR cameras, provide a very useful foundation for thinking about working at magnifications above 1:10 and especially above 1:1. Extensive bibliography.

H. Lou Gibson is one of the Englishmen that Kingslake brought to EKCo. He's best known for IR photography. His Photomacrography pamphlet is the most frightening photography book I've ever read.

[Nathan Potter]

Dan, thanks for reminding me. I see I have that 1977 Kodak publication which is quite good but with some weaknesses, as you point out.

Another useful Kodak publication was their "Photography Through the Microscope", ISBN 0-87985-019-1, 1974. It of course deals with high magnification and is pretty informative about some sophisticated techniques such as interference contrast and the Nomarski version of such.

Nate Potter, Austin TX.

[Serge S]

Can any of you recommend a good lightbox for shooting negs with my 5D. My Bretford Acculight has hot spots....there must be something better out there and I don't have any local shops so I need to mail order.

Thanks,

Serge

[Peter De Smidt]

You might try modifying your box a bit. For instance, you could get some white foam core. Make a flat-topped pyramid, with the bigger opening sized to fit over your light source. At the smaller end, put a piece of diffused plexiglas. You will lose light, of course, but you should be able to make a pretty even source.

[Serge S]

You might try modifying your box a bit. For instance, you could get some white foamcore. Make and inverted pyramid, with the bigger opening sized to fit over your light source. At the smaller end, put a piece of diffused plexiglas. You will lose light, of course, but you should be able to make a pretty even source.

Thanks Peter I'll give it a shot

[janosch simon]

very interesting project :-) you guys think it would be possible to use an corexy table? http://corexy.com/theory.html dont know how to setup the steppers then :D
cheers and thx

[Daniel Moore]

very interesting project :-) you guys think it would be possible to use an corexy table? http://corexy.com/theory.html dont know how to setup the steppers then :D
cheers and thx

That would take a lot of belt length, much more so than with other systems. That concerns me. Bottom line is we won't know until you try it : ). Could just work.

[janosch simon]

That would take a lot of belt length, much more so than with other systems. That concerns me. Bottom line is we won't know until you try it : ). Could just work.

HMMMM but with the panoscanning technique we have nevertheless overlapping so the positioning is not that critical or am i wrong? HMMM but the other xy tables build so high and that corexy concepts intrigues me :D

[Peter De Smidt]

Required repeatability increases significantly when multiple images of a negative are taken. The issue is the difficulty of stitching areas without much detail, such as a white wall, blank sky..... A good way around this is to build a template in PTGui, using a negative with good detail everywhere to make the template. If your scans are highly repeatable, then you can simply apply the template to future scans. With Daniel and my systems, this works really well.

[jesse1996]

adding a bit of what i know in terms of this stuff. I think the rise of 3D printing will help significantly in terms of manufacturing. Bear in mind a kid in middle school was able to print an entire set of braces for himself (many individual sets of braces) with little to no proper equipment for less than $100. With all the higher end plastics available today that weren't back in the 90s/2000s and more accessible communication in terms of manufacturing. I'm willing to bet with a decent start up lump sum someone with the know how could easily get a modern drum scanner onto the market. whether it be for pros or for the normal person with a few thousand burning a hole in their pocket. yes drum scanners back in the day were expensive, but so were the first computers, nowadays one can walk into walmart and get a half decent machine for $600 thats millions of times more powerful than the $10k beasts from back in the day. why not the same for drum scanners? If anything I'm willing to bet one could take an old howtek 4500 or 8000 and scan all the parts with a 3d printer. print off the parts, keep the moving parts metal for strength, and just update the software and processors to accommodate todays much more capable machines. I have a Macbook air and I've edited 3gb files on it before (granted it was a pain) Im willing to bet it can be done with around $1million TOTAL to get a new scanner on the market for under $5k. at the very least someone will be out a million dollars and there will be a few hundred modern scanners floating around for labs and pros to use.

[jesse1996]

I should also add there is a fairly small company called creekside digital that uses a phase 1 80MP digital back over what appears to be an enlarger chassis with the camera system attached and the film on a ligthbox below. Honestly its a great idea but for some reason they impose some comparatively small size limits to all formats compared to what one could do with a moderately priced flatbed or cheaper drum scanner. In practice they're quite clever but my only beef is the file limits.

[james zhou]

I have made side by side comparisons of scanned images (using Fuji finescan 2750 from 8x10 color transparencies) and a Nikon D800E (stitched shots of the same 8x10). The DSLR images are much better, more resolution, better contrast and richer colors.

[Leigh]

I should also add there is a fairly small company called creekside digital that uses a phase 1 80MP digital back over what appears to be an enlarger chassis with the camera system attached and the film on a ligthbox below.
That sounds like the ancient Nikon slide copying system with a modern camera attached.

You can do that with any digital camera and any light box.

- Leigh

[mksystem]

After reading this forum I build such a scanner myself. I have no large format negatives (or ever MF) so I test it scanning old 35mm films. I use Nikon D600 and Nikon 60mm/2.8D.

I usually scan negative at 1:1 magnification so I don't need stitching panorama. I get 24 megapixels (4000 dpi) from negative. I also have cheap macrotubes so it possible get 2:1 magnification (maybe more). At maximum magnification I got 120 megapixels (9000 dpi) from one negative (12 D600 frames). I can't see big difference between 120 mpx and 24 in my scan but maybe with better film and camera/lens it's possible to get more quality scanning at higher than 1:1 magnification. I think that 50 mpx per negative will be enough. Here is a video of scanning process.

I have 30x30cm light-table which is moved by two nema17 stepper motors controlled by Arduino.


https://www.youtube.com/watch?v=p9xJ-R3Ku5s
160716

[Peter De Smidt]

Good stuff! Thanks for posting. My own experience with my D600 is that there isn't much advantage going above 1x magnification, even with lenses optimized for those magnifications. I did a test with a 35mm image taken with Technical Pan film, shot on a very heavy tripod, using the taking lens's best aperture.... I compared scans done with a 75mm Rodagon D f/4 @ 1x magnification to one done with a Nikon 5x Measuring Microscope lens, and maybe there was a tiny difference. But maybe not. There was a huge difference when I scanned a high resolution test chrome on glass resolution testing plate. So the higher magnification setup did produce more subject detail, if there was such detail on the subject, but at least in my case, my film negatives didn't have useful detail that needed the increased magnification. If there wasn't an obvious difference using TP on 35mm, I doubt very much that there would be any difference with medium or large format negatives. Using different lenses might give a different result. If the lens used at 1x isn't very good, a scan at 2x might out perform it.

[SURF]

Hi Peter! Any words about geometry and microgeometry? Do you use any profile for that? Have you checked those BTW? What kind of adjustments do you use when you put the camera in place?

That must be a nice machine. Saw it on youtube some years ago.

PS. I have not read all the thread.
PPS. Good thing that you bought USAF target. ;-)

[Peter De Smidt]

Hi Surf,

By "geometry and mircrogeometery" do you mean size distortions from stitching? If so, I haven't done extensive tests, and my scanner is currently in pieces, and thus it's unlikely to happen soon. By "profile" do you mean a template for stitching? If so, yes, I made a special negative to created a template in ptgui. The scanner is repeatable enough to allow other 4x5 scans to use the same template. Regarding mounting the camera, I use a long Arca quick release plate, 8" I think. The Nikon extension tubes are bolted to it. It mounts to a Velmex 4000 series unislide via an Arca clamp. Once the lens system is mounted, it stays on the Velmex. The Velmex can be moved very precisely to focus. I hope that helps.
a

[SURF]

Thank you, Peter!


By "geometry and mircrogeometery" do you mean size distortions from stitching?
Sure. :-) I've just found a better term for that: warping. It happened that I hate warped images. And stitching often produces a lot of warping. Looks like it is not an easy task to fight them.


"This headache inducing illusion is simply a static image of a green background with a series of blue dots, however when you look at it the whole thing appears to move and warp in a wave-like fashion."

http://www.optical-illusionist.com/imagefiles/warpeddots.jpg


By "profile" do you mean a template for stitching?
Not really. There are no perfect lenses and the profile can correct each shot distortions, thus eliminating warping in stitch.

Why I asked about camera mount is because it's very hard to place it exactly to the same position.

[Peter De Smidt]

Regarding lens profiles, a lens designed for 1x magnification has very little distortion at 1x. My understanding is that a symmetrical lens can perform very well there. I use a Rodagon D 75mm lens optimized for 1x. My limited understanding is that PTgui corrects for lens distortion, but it's better if there's as little as possible already there.

Regarding mounting, the lens system doesn't move when the camera is mounted. I do check focus, but it's rare for there to be an issue.

[SURF]

Rodagon or Magnagon? Magnagon is just great. Perfect for the task. They say that it's Rodagon-D, but I'm not sure.

My inderstanding (limited) of PTgui is that it can use lens profile, if it has that profile in the base.

"Lens system doesn't move when the camera is mounted" - that's what I did not understand at first. You are right. In that case remounting camera makes no harm.

[Peter De Smidt]

I have both a Rodagon D and a Magnagon. With my examples and in my system, the Rodagon performs better. There are two Rodagons, an f/4 and an f/4.5. The first is optimized for 1x, whereas the second is optimized for 2x, or 1/2x reversed. The Magnagon seems more like the latter.

[Luisifer]

One my attempt in progress for a few years (now i am changing axes to RPi3 HTTP REST controlled over wifi).
http://12in.cz/fotografie/velka/40_10_Digitalizacni-stolice
(prepared for 12x20" maximum film size and 5:1 magnification, light over strobe ELC Pro HD 1000)

[SURF]

I have both a Rodagon D and a Magnagon. With my examples and in my system, the Rodagon performs better.
Can I ask you when you will time to scan the resolution target with your lenses. At the moment I do not understand big thing: if the lenses outperform the sensor why is the difference there?

[Peter De Smidt]

For there not to be a difference, the lens would have to outperform the sensor in every way, resolution, contrast, chromatic aberration.....That's not the case. I've already taken those pictures many years ago. Even if I could find them, they would be of very limited use. Comparisons are extremely difficult to do well. One's not done at the same time by the same operator in the same system are unlikely to provide much information, and even then we'd be looking at a very small sample of lenses. Would even 10 samples of a lens be representative of all production? Unlikely. What does make sense is doing your own testing in your system to see which one performs best for you. In my system, that was a Nikon 5x Measuring Microscope lens. But using that lens to photograph a large negative would take way too much time, and while the resolution would be better than any scanner I've worked with, what about errors introduced by stitching all of those frames? What about the cost of all of those shutter actuations? Would there be any more detail available in a print made with that lens compared to, say, a Rodagon D 75mm f/4? In my system the answer was "No," and that's despite giving better performance with a high resolution test target. For me, 1x magnification is the sweet spot. Going higher didn't lead to any better results, and that includes when scanning 35mm Technical Pan shot as carefully as I could manage, i.e. huge tripod, mainly 2d subject, optimum aperture, cable release, mirror lock-up....... If there wasn't a difference there, it's unlikely for there to be one with the larger format film.

[SURF]

I've already taken those pictures many years ago.
I would not call 5 years as many, but it's me. I've seen those tests. I agree: they do not say much about the difference.

While using ptGui do you examine medium-maximum pixel shift? Still have no idea how the glass influences it. Have to test myself I think.

[Peter De Smidt]

https://www.dropbox.com/s/ysiy8zg6enz7blw/Rodagon_D_1x_D600_no_sharpening.jpg?raw=1

Rodagon 75mm f/4, Nikon D600, 1x magnification, no sharpening.

[SURF]

Thanks! I will post 1x Magnagon tests in Lenses thread. Both are great lenses for sure.

[Two23]

How do you mount a Rodagon to a Nikon?


Kent in SD

[Peter De Smidt]

Extension tube/bellows with an f-mount to 39mm adapter.

[Luisifer]

I'm just trying to render first HP5+: https://youtu.be/GV_itAFJrlI
173414
(later i have to find how to get results directly with non deformed rectangle)

[Daniel Moore]

Do you have any build pics or details on the film carrier itself? Very interesting machine.

For the pincushion distortion, I'd start by not using Panini projection for output, you should be able to use Planar or Orthographic projection settings. Be sure to assign a very long focal length lens, do not use the actual focal length, try 1000 - 2000mm to start with.

[Luisifer]

HP5+ is quite coarse so it is more about trying to get all the grain in this case. Another side should be color film or films with lower ISO in general.

I know that planar should be the best but this time i got worse deformation with planar projection setting so it is reason why it is panini this time. There was possible to set top and bottom line more correct than in other projections. I didn't tried higher focal length than 999. Sooner it was maximal focal length so i set 999 mm. If it is possible to set longer now i will test it later.

[Luisifer]

I stopped rendering after more than day (deghosting was like a stuck) and surprised me that it is possible write down really looong numbers. It should be better than before and with planar projection.
173486

------------later progress-----
ops :-) it looks like very hight numbers aren't the best. Some __.cpp error and RMS fall from 2.14 to 193.96. I have to try some uncropped number.

[Luisifer]

Daniel Moore: thanks for the tip, 2000mm seems to be the best. And RMS raised to great 1.4.
http://12in.cz/temp/RMS_1_4.jpg



Update: well done, 65 GB file after crop and grayscale working space.
http://12in.cz/temp/in_to_the_marrow.jpg



Update: for demonstration, here is 700 Mpx version (but retouching is not finished):
http://12in.cz/temp/vidlak.zip (zipped JPG file, 502 MB)