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Making a scanner with a DSLR
So instead of belly-aching over how crummy flatbeds are and how old drum scanners are a pain to deal with, why don't all the engineers here tackle creating a new, modern drum scanner that's as open-sourced, off-the-shelf, and future-proofed as possible?
A lot of those old drum scanners were pre-PC, they must not be that complicated... Other than the drums, what else needs to be fabricated rather than bought? Isn't most of the value in the engineering, not the hardware? Heck I can buy $50 lasers at Home Depot.
What if 1,000 serious film photographer put down $1,000 deposits on a $2,000 price-point, Heathkit-style drum scanner? Wouldn't a million dollars of pure R&D money be more than most of the big corporations spent on their classic drum scanners back in the day?
We could get those argumentative lawyers that keep pestering the mods to set up a clean not-for-profit organization to administrate the project. Make it open source, everyone contributes... Ending up with a Volkscanner for the masses, able to handle 8x10 and modern software and interfaces (just have a network or even wifi interface)... Best $2000 ever spent - you know there are easily more than 1,000 people who would jump at this.
So why not?
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Re: Making a New Modern Drum Scanner
Man that must be some killer weed you're smoking.
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Re: Making a New Modern Drum Scanner
Well it seems older drum scanner used photomultiplier tubes. I'm betting you can't get those anymore. Newer ones use CCD arrays which are not easy for amateurs to deal with. It seems more practical to put a whole bunch of APS-C sensors on a device that can position them. You take one picture with the whole bunch of sensors, shift the sensors (because there will be borders between the sensors), take the picture again and stitch the result. If this could be done with an 8x10 cameras I'm sure the resulting digital image would be in the Gigapixel range easily.
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Re: Making a New Modern Drum Scanner
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Re: Making a New Modern Drum Scanner
Serious question: Is a drum scanner inherently better than a flat bed, given all (most) other factors being equal? Or, is it a matter that the old high end drum scanners were better than the present consumer flatbeds? I mean, if the Epson V750 "Pro" msrp's at $850, and you're willing to spend $2000, what could be done with a flat bed at the $2000 price point (that only needs to go up to 8x10 - I realize there are larger flat beds.)
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Frank Petronio
What if 1,000 serious film photographer put down $1,000 deposits on a $2,000 price-point, Heathkit-style drum scanner?
*shudder*
I used to work for a manufacturer (yes, we had our own pick-and-place machines) and my boss designed part of the Intel 80386, and the company president wrote the book on the Intel i860, literally. I can see $2,000 in just parts alone, and the result would look ugly, to put it mildly.
Hurdles: Focusing, stability, and speed. These are mechanical things. The "easy" stuff, like interface, is very simple: network connection. A 1-Gb network connection is easy and will be adaptable for at least a decade or two into the future.
There has to be a lens assembly commercially available which can be actuated by stepper motors. The mechanics for the drum would probably have to be custom machined.
And what about when it breaks down? Then you might have a $2000 hunkajunk and just hoping that somebody has some free time to help you out.
$2000 can buy a really good flatbed scanner with decent film scanning performance.
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Re: Making a New Modern Drum Scanner
Yeah a drum scan will have less noise and be "clearer" with a little extra range. Not that you can't work with Epson scans - I do. There is always going to be a small market for people who want the best, but it will always be there too. An even bigger market is for the photographers who is willing to pay 2-3x what a good Epson costs.
How is not something that could be manufactured in a clean garage?
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Re: Making a New Modern Drum Scanner
Having operated them in the past, drum scanners were bitchy, painfully slow, required disgusting amounts of service and quite extraordinary amounts of consumables (Mylar sheets, fluid, cleaner, cleaning wipes and the odd drum and lamp ever so often). Nobody doing a run-of-the-mill scan service can still do that profitably on a drum scanner, and the few individuals still making money out of them have tweaked their scanners to perfection, and probably would not be inclined to switch to a new scanner built to meet a much lower price point...
Currently the market is that saturated with old pro scanners that there is no profit in any new high end scanner development. Whenever there will be enough demand to start high end scanner building again, it will be in low numbers, and will probably take a entirely different direction - more like a 2D Imacon or those micro-movement enhanced medium format backs.
A high quality macro lens, FF or APS-C sensor and a piezo base for micro stepping the sensor to multisample at a finer than raster pitch should today be capable of delivering above 100MP scans at pro digital camera quality, using current off-the-shelf components rather than anything proprietary or not made any more - which is essential if the thing must be affordable enough for enthusiasts and archivars rather than the advertising industry, and has to be made by the ten rather than the thousand.
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Re: Making a New Modern Drum Scanner
Quote:
A high quality macro lens, FF or APS-C sensor and a piezo base for micro stepping the sensor to multisample at a finer than raster pitch should today be capable of delivering above 100MP scans at pro digital camera quality, using current off-the-shelf components rather than anything proprietary or not made any more.
Most useful comment. So is anyone doing this or working on it yet? Or where do you buy it and how much does it cost?
Isn't the drum scanner always going to have an advantage in dynamic range, unless they start to develop camera sensors with a greater-than-current range? Are there any roadblocks to getting a higher range than film out of a digital sensor? Or can you do a high and low exposure and combine them in HDR?
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
domaz
Well it seems older drum scanner used photomultiplier tubes. I'm betting you can't get those anymore. Newer ones use CCD arrays which are not easy for amateurs to deal with. It seems more practical to put a whole bunch of APS-C sensors on a device that can position them. You take one picture with the whole bunch of sensors, shift the sensors (because there will be borders between the sensors), take the picture again and stitch the result. If this could be done with an 8x10 cameras I'm sure the resulting digital image would be in the Gigapixel range easily.
Yeah I'd throw a bunch of cheap sensors and a bunch of cheap computing power at the problem. I'd make everything static, just greatly overlap each sensor's image field and have the computer correct for lens inaccuracies, film curvature and average out the noise.
...Mike
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Re: Making a New Modern Drum Scanner
I could contribute significant sweat equity in the form of design work, both mechanical and electronic. I certainly have the credentials for same.
I can also do the prototype, since I have a full machine shop and an electronic development lab.
This is actually quite easy and simple. Only the film and its support drum move. Everything else is in a fixed position.
- Leigh
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Re: Making a New Modern Drum Scanner
Essentially macro gigapans, probably with different stitching algorithm. The hardware is out there already.
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Mike Anderson
Yeah I'd throw a bunch of cheap sensors and a bunch of cheap computing power at the problem. I'd make everything static, just greatly overlap each sensor's image field and have the computer correct for lens inaccuracies, film curvature and average out the noise.
...Mike
I was thinking about this at the point of capture- a replacement for film. But the only way to overlap each sensor's image field is to put a lens on each sensor. Can any kind of lens focus on the image being put out by the Large Format lens in front of it?
Diagram to make things clearer:
SM--L
S=array of sensors
M=array of micro lens for each sensor
L=LF lens
Is there any such micro lens(M) that could focus the image from the LF lens(L)?
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Re: Making a New Modern Drum Scanner
For LF scanners don't have to be much better than a really good flatbed or an average PMT scanner to please the majority. It's with the smaller formats (135, 645, 2-1/4) where the 3 to 6 micron apertures of the fine-art-purposed PMTs really shine. I see an Aztekbusiness-model opportunity for others who might adapt and repurpose some of the other makes of hardware that are often practically being given away now. But it would be hari Kari to start from scratch with all the idled prepress gear flooding the warehouses.
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Re: Making a New Modern Drum Scanner
OK I am only going to show more ignorance here, but aren't the flatbed scanners we've already got doing this same thing? Doesn't a Creo move it's sensor all over the place in the X and Y axises? So it is simply a matter of using a larger chip from a professional digital camera and an overall tighter, more precise and tuned mechanism?
So the scanner improvements would be kind of like the difference that chip size makes in quality, such as in going from a $100 point and shoot to the latest medium format digital back?
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Frank Petronio
OK I am only going to show more ignorance here, but aren't the flatbed scanners we've already got doing this same thing? Doesn't a Creo move it's sensor all over the place in the X and Y axises? So it is simply a matter of using a larger chip from a professional digital camera and an overall tighter, more precise and tuned mechanism?
So the scanner improvements would be kind of like the difference that chip size makes in quality, such as in going from a $100 point and shoot to the latest medium format digital back?
Is there much difference in quality between a teeny cheap sensor and a big expensive sensor if they're both working at their preferred ISO?
(I'm ignorant too here.)
...Mike
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Mike Anderson
Is there much difference in quality between a teeny cheap sensor and a big expensive sensor if they're both working at their preferred ISO?
(I'm ignorant too here.)
...Mike
Really, just make more, smaller passes and make it slower and cheaper.
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Re: Making a New Modern Drum Scanner
This is sort of what I had in mind.
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Re: Making a New Modern Drum Scanner
Wow that is cool thanks
But still, in absolute terms, a good drum scanner will capture a longer tonal range with less noise, even though something like the GIGAmacro could possibly beat it on resolution. Or?
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Re: Making a New Modern Drum Scanner
I think Frank is on to something and not just on something.
Why are there no mid-range film scanners? Film scanners jump from the Epson v700/750, a high end consumer grade scanner, that goes for around $700 up to something like the Flextight scanners that sell for upwards of $10,000. There is nothing in between. Why not?
Surely, someone could build a scanner similar to the v700 with some upgrades to all the critical pieces. A better sensor, better optics, precision machined gears, high precision stepping motors, and a really good film holder. I think such a scanner could come in at a price point around $2,000 to $3,000. I know the market would be limited but I still think there is some money to be made there.
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Mark Stahlke
I think Frank is on to something and not just on something.
Why are there no mid-range film scanners? Film scanners jump from the Epson v700/750, a high end consumer grade scanner, that goes for around $700 up to something like the Flextight scanners that sell for upwards of $10,000. There is nothing in between. Why not?
Surely, someone could build a scanner similar to the v700 with some upgrades to all the critical pieces. A better sensor, better optics, precision machined gears, high precision stepping motors, and a really good film holder. I think such a scanner could come in at a price point around $2,000 to $3,000. I know the market would be limited but I still think there is some money to be made there.
Seems like the institutional and government offices alone would be good customers, not to mention photographers. Build it professional quality, even like those old Agfa Arcuses.
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Re: Making a New Modern Drum Scanner
A good drum scanner has greater dynamic range than a ccd scanner, but it doesn't have greater range than an HDR style multi-exposure ccd system, since the latter can have as big a dynamic range as you need. All you need to do is to take more exposures at different levels. A variable light source would also be good, but you'd have to be careful of spectral shifts. Perhaps neutral density filters would work.
The big problem is alignment, and the precise movement of the film. (I think it's better to move the film holder than the sensor.) The level of alignment is what it would take to make a huge print under an enlarger. The film must stay perfectly flat and parallel to the ccd sensor and lens.
Some type of x-y position system would be needed for the negative carrier, perhaps with two calibrated lead-screws.
So, get, build or modify a light box with a very even source, one that's quite a bit better than the industry standard type boxes. (I don't know how repeatable flash equipment is, but if it is repeatable enough, it might make a good light source, as you can use a very short duration of flash, which should help with vibration. You'd still need a constant source for focusing.) Make a tray that goes on top, it doesn't have to touch the light box, which will hold a film holder that can be moved in a repeatable, grid-like fashion. A clam shell holder with p95 acrylic would be ideal. You'd then need a mount for the camera. Since it wouldn't have to move much, it should be a multi-column mount for stability.
A macro bellows, such as a Nikon PB-4, along with a high quality enlarging lens would be a good choice, probably a 50mm, as they're capable of the highest resolution.
The carrier stage would have to be masked very well, and the light would half to be blocked from the front of the lens to the negative.
Operate the camera remotely through live view, although focus would be manual.
The whole system would have to be very sturdy and well-isolated from vibration.
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Re: Making a New Modern Drum Scanner
Looks like the GigaMacro is already available. One would only need a backlight to scan transparent film media. In the $15 K range that's not too bad. But at the advertised resolution there are a bunch of very precision mechanical parts especially for X and Y motion that are costly. Essentially this is a step and repeat camera where the resolution and contrast will be limited by the macro lens. Scan time will be limited by the field of view of the macro lens and stitching time can be added to the physical scan time.
A higher magnification lens heading toward a microscope objective will provide resolution down to a few um but a small FOV, so many more images are required. But higher magnification requires tighter focus control, or auto focus, so more precision. Mechanical precision is expensive.
What's less expensive is signal processing. Thus it may be possible to trade the mechanical precision in X and Y motion for pattern recognition and image reconstruction algorithms; meaning the scan can be sloppy if the images overlap.
Lots of possibilities beyond the GigaMacro but using a high quality CMOS sensor with a magnifying macro lens would make sense and ultimately provide a less expensive machine than using a drum.
Nate Potter, Austin TX.
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Re: Making a New Modern Drum Scanner
Problem here is(IMO):
We're not looking to design a line of cars, with a cheapo/intro model, a medium($40k/year) model, and a heart surgeon's model w/ all the bells and whistles ;).
The high-end scanners like the Azteks, Heidelbergs, Creo/Kodak's were designed for PROFESSIONAL use. That means MORE MONEY SPENT. The latest generations of drum scanners from Aztek, Heidelberg, Screen, and the latest hi-end flatbeds like the Kodak Eversmart Supreme II's, no expense was spared to put the BEST tech into them, and for them to perform flawlessly(well, when used properly). Just like the top-tier Ferrari's, they need a servicing every now and then. Just part of doing business. Bulbs and belts need to be changed, lead screws need to be lubed, and sometimes, a full goings-through needs to be performed to make sure no bugs pop out when not wanted. Of course many people neglect their "normal maintenance cycle", thinking "That won't happen to me". Well, it happens.
If you want the best tech possible, and I'm assuming 16bit TIFF file output, then you'll need to pay for it. PMT's aren't cheap, and small companies like Aztek(I was there yesterday actually, dropped in since I was in the neighborhood, they're 3 people total I saw in the office, YES... 3 people). They need to be paid, and keep enough to keep the lights on.
The problem I see here is two-fold: You have your lab owners/scanner operators(Lenny for instance), and you have your "amateurs"(some who might know just as much as the "pros", if not more, but might only be scanning for themselves, not as a service for profit). That's the KEY word: PROFIT. Its called keeping the lights on. The Aztek Premier will clock in around $50k after the scanner, mounting station, a drum or two, Pro software($1500), computer to drive the scanner, a shipping crate to hold it during transit, and $1k to ship it to you across the country/world, etc... Yes, its expensive. But you can buy an 80mp digital kit, outfit it with 3-5 "top tier" lenses, and still be around the same amount of dough in the end. If you're scanning/shooting for yourself, then its your call. But in the end, if you want to deliver the goods to paying clients who are willing to spend $100+ on a scan, then you'll probably want the best machine w/ the best support possible. In the USA, IMO, that's Aztek. They've been sooooo helpful in aiding me in my acquisition of my drum scanner, and answering technical emails/phone calls w/o asking for $$$ in return. They know I'm serious about my craft, and don't have money to burn, but I don't bullshit with their time either. They're professionals(IMO), and professionals SHOULD be paid.
If I was going to introduce a drum scanner, I'd want to make sure you can mount up to 11x14 film on it. And I WOULD NOT be doing it for less than $40k. If I hadn't already gone with a drum scanner, I'd be going with a Kodak Eversmart Supreme II flatbed(and still fluid mounting almost everything on it). IMO, its more flexible, and the minor difference in file quality(IMO) isn't worth the headache and risk of damaging someone's film on a fast-spinning drum scanner(even though I know how to properly mount film).
Oh, what about overhead on these "1000" scanners, there's gotta be tech support on these, someone to talk to when something goes wrong. That costs money, its called overhead.
I think that drum scanner manufacturers INTENTIONALLY priced themselves high, just so the "small fish" photographers w/ the "I need the best" mentality REALLY think twice before ordering something like these machines. There's more involved than most people really think...At least I know there is, I'm learning a buttload, and I'm not technical(but I'm learning I need to be :D)
just my $.02
-Dan
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Re: Making a New Modern Drum Scanner
This is a neat challenge. When my Cezanne dies, I'll probably pursue it.
Sure, we have many disadvantages compared to a big company, but we also have many advantages. The software available now for raw processing is much better than any scanner software I've used. We can replace our sensor, i.e. the camera, for a modest amount, and they have improved dramatically. Lots of the macro bellows and so on are available for little money, and enlarger lenses are close to free. In addition, we don't have to use materials that are compact or easy to move. For instance, we can use a 1/2 inch (or thicker) piece of glass as a base to slide the negative holder on, and many of us already have glass negative carriers for our enlargers. It's automating the whole thing that would be the really big challenge, but it doesn't really have to be that automated. If it must be, there are DIY CNC machines that have to be accurate down to a 1/1000 of an inch, and a technically inclined person could probably modify such a device.
In addition, commercial scanners have to be so precise because they only read a couple lines at a time, and the sampling has to be incredibly precise so that all of the sampled lines can be put together. With a dslr, though, you take reading of a much wider area, and as long as each sample area is overlapped enough, it's no problem for software to put the pieces together.
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Re: Making a New Modern Drum Scanner
This is something I've been looking into for some time hence the reference to the GigaMacro. There is an experiment that can be performed to validate the approach which is to construct a pin grid system that allows systematic movement of a stage holding a target below a macro lens. No stepper motors involved, just shoot and manually move to next position.
Re focus, there is a technique used in photomacrography that might be of use called stacking, where the stage is moved along the lens axis to bring various points in focus. Not sure the utility in this context, but just brainstorming.
Re lenses, if you need to get down below 1:1 it might be worthwhile looking at microscope objectives. I've been seeing some pretty nice looking stuff from those. There are a couple of configurations, such as objective on bellows and infinity objective on a lens.
When is it more advantageous to move the imager vs. moving the stage?
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Jim Michael
<snip> There is an experiment that can be performed to validate the approach which is to construct a pin grid system that allows systematic movement of a stage holding a target below a macro lens. No stepper motors involved, just shoot and manually move to next position.<snip>
That is what I have in mind, as well.
Quote:
Re lenses, if you need to get down below 1:1 it might be worthwhile looking at microscope objectives. I've been seeing some pretty nice looking stuff from those. There are a couple of configurations, such as objective on bellows and infinity objective on a lens.
That would certainly be worth looking into, especially for smaller than LF film. For LF, something on the order of 1:1, i.e. image size of one sampled area equals image size of sensor, should give pretty high quality. With my digital camera, an older model, that should allow a 10x enlargement or so, assuming the negative is sharp enough. That's bigger than I'd ever want to print. 1:1 would be well within the capabilities of an enlarging lens on a bellows.
Quote:
When is it more advantageous to move the imager vs. moving the stage?
Well, a camera/bellows/lens combo is quite heavy, and it would be non-trivial to be able to move it precisely, perfectly parallel to the negative, and without inducing vibration. With the negative stage, on the other hand, you could use some thick textured acrylic (P95) to make a clam shell holder. You could put a small foot in each corner of teflon (or similar) tape, and you could slide it on a very heavy sheet of glass.
Here's picture of coraline algae growing on the glass of our aquarium. The colony was about 1/4th" in diameter. I used my d200, a Pb-4 macro bellows, and an enlarging lens. I simply eye-balled the alignment, and my D200 doesn't have live view.
http://i955.photobucket.com/albums/a...t/Coraline.jpg
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Re: Making a New Modern Drum Scanner
If we just make a mechanical product that accepts a wide range of digital cameras it would allow you to choose your price/quality point by using a $500 camera or an $8000 camera. And as digital camera technology continues to scale so would the system, the mechanical part we build would not obsolesce.
Precision adjustment would be needed to set the height and level the plane of the camera. X Y placement needn't be precise as long as there's overlap because the stitching software can easily deal with the slop.
...Mike
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Re: Making a New Modern Drum Scanner
Yes! You guys have the idea both mechanically and optically. This can already be demonstrated using a light table and digital camera with a good macro lens of low distortion. Use conventional stitching software to reconstruct the image. The key here is that this is not live image capture - the subject is stationary.
The next task is to build a prototype that more or less automatically does the same thing, faster and more precisely. The trick in all this is to use low cost OEM parts on a solid chassis in order to keep the ultimate cost down. The engineering is relatively easy - the market analysis not quite so.
Nate Potter, Austin TX.
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Re: Making a New Modern Drum Scanner
The usage problem I see with a stitching scanner is that there is no way to preview to set exposure/levels without actually doing the scan. If it had a high speed mode, it could do a quicky scan for setting exposure. Remember DSLRs are pretty sensitive to exposure accuracy.
It's a constructive comment because I like the idea.
I would agree that presently available stitching software can take care of alignment imprecision, except for focus of course. I would think a cnc router table would be a good start. Moving the film instead of the camera would provide an easier to build light source, as a smaller even diffuse light is easier to build that a very large (11x14+) diffuse source.
Putting the whole thing in a cabinet that is dust proof and light proof is a good idea. Not everyone has a clean pristine lab to set such a system in. To dampen vibration, electromagnets could temporarily attach the movable stage to it's frame during exposure, and release it's grip during positioning.
The stage itself could be a filmholder made of white diffuse plastic, or at least the center part of the it. If the film moves a little during positioning, the stitching software can take care of it.
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Re: Making a New Modern Drum Scanner
And what about dynamic range? Won't it only be as good as a digital camera?
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Frank Petronio
And what about dynamic range? Won't it only be as good as a digital camera?
Yes, but HDR techniques can ameliorate that.
The DSLR based "scanner" is starting to sound like a glorified copy stand.
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by Mike Anderson
If we just make a mechanical product that accepts a wide range of digital cameras it would allow you to choose your price/quality point by using a $500 camera or an $8000 camera. And as digital camera technology continues to scale so would the system, the mechanical part we build would not obsolesce.
Right! And our sensor system would be current and servicable for a reasonable amount, unlike pro-scanner repair costs.
Quote:
Originally Posted by Mike Anderson
Precision adjustment would be needed to set the height and level the plane of the camera. X Y placement needn't be precise as long as there's overlap because the stitching software can easily deal with the slop.
Yep. Good points.
Quote:
Originally Posted by Nathan Potter
<snip> The key here is that this is not live image capture - the subject is stationary.<snip>
Good point.
Quote:
Originally Posted by jp498
The usage problem I see with a stitching scanner is that there is no way to preview to set exposure/levels without actually doing the scan. If it had a high speed mode, it could do a quicky scan for setting exposure. Remember DSLRs are pretty sensitive to exposure accuracy.
That’s true, although one could use the light table to figure out the brightest area of the negative. Take a test frame of the brightest area. Adjust exposure. Now take a picture of the darkest area. Is the dynamic range enough? If yes, proceed with the “scanning”. If no, take another frame with more exposure. Let’s just say that one stop more exposure would be enough. Now take two pictures at each sample site, using auto bracketing to give the correct exposures. Before stitching, use HDR software to blend the exposures. Stitch the blended exposures to get your file. While I haven’t tried this, I expect exposure fusion would work much better than traditional HDR tone-mapping.
Quote:
Originally Posted by Mark Stahlke
The DSLR based "scanner" is starting to sound like a glorified copy stand.
I agree. Getting fancier, though, would be very expensive.
If we work on this, we could come up with a DIY plan, including a parts list, workflow tips…
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Re: Making a New Modern Drum Scanner
Why not build your own car? This is really a ridiculous idea if you ask me.
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Ed Kelsey
Why not build your own car? This is really a ridiculous idea if you ask me.
Ed, do you wake up ready to shit on everything all day long or do you just squat and pucker up for this forum?
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Re: Making a New Modern Drum Scanner
As has been mentioned, a high degree of accuracy is not needed, the stitching software can take care of that. Perhaps the RepRap 3d printer platform (or something similar) could be modified to provide the moving baseplate? It's a very cheap system, proven technology, both hardware and software, and not difficult to imagine how it might be adapted to accept a light box and camera mount- plus, it's all open source-
http://reprap.org/wiki/RepRap
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Ed Kelsey
Why not build your own car? This is really a ridiculous idea if you ask me.
I haven't chimed in on this thread because I know dick about scanners.
But I do know that very often, a small and dedicated group can come up with a product that blows the doors off the commercial offerings.
Why not let them have fun?:)
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
jp498
The usage problem I see with a stitching scanner is that there is no way to preview to set exposure/levels without actually doing the scan. If it had a high speed mode, it could do a quicky scan for setting exposure. Remember DSLRs are pretty sensitive to exposure accuracy.
Making each region-capture a 5 shot bracket wouldn't take much longer than a 1 shot. An HDR approach might be the more popular workflow anyway in which case setting exposure needn't be precise.
...Mike
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
jb7
It certainly should be possible.
We should probably do some tests just to see what the resolving power and contrast performance of the optical/sensor system would be, not doing any stitching to start. If we can get the quality we want on one frame, then we could move on. If we can't get the quality we need on one frame, then there would be no point in automating the process. We should probably aim to at least achieve the quality achieved by one of the pro-scanners. I have a Cezanne. Supposedly it's resolution is very good, around 6000 line pairs per inch, but it's dynamic range can't match a good drum scanner. I also have a PB-4 bellows and a bunch of enlarging lenses. And so I can compare (and post) comparisons. The main issue would be that my D200 doesn't allow live view, and so very precise macro focusing is a pain.
Quote:
Originally Posted by Mike
Making each region-capture a 5 shot bracket wouldn't take much longer than a 1 shot. An HDR approach might be the more popular workflow anyway in which case setting exposure needn't be precise.
Great point, Mike.
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Re: Making a New Modern Drum Scanner
I was just given a Nikon SB-28 Speedlight. It goes down to 1/64th power. I'm considering making a light source out of white styrofoam and difused plexi for this experiment. Does anyone know how repeatable the intensity of these flashes are? I guess I'll find out. Maybe I'll trying using one of the mixing boxes from my De Vere 504 for the light box.
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Re: Making a New Modern Drum Scanner
For cinematography they are using a log interpretation of exposure to achieve a DR on the order of 14 stops (there's a whitepaper on Sony's site with the math). Perhaps something like that could be employed to take advantage of the HDR results.
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Re: Making a New Modern Drum Scanner
Peter, I'd guess the exposures would be pretty consistent if the flash is in a fully manual mode and the flash is allowed to fully recycle.
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Re: Making a New Modern Drum Scanner
What if there were 2 parts, a bridge to hold the camera and a light box. They would both placed on a flat surface like a piece of glass (not included).
The light box would have wheels and motors within, it would scoot itself around the surface like one of those robot vacuum cleaners. There would be no external drive rods and assemblies.
The downside of this is lack of precision in locating the light box. We agree that the precise X Y location isn't important.
But what about rotational/alignment precision? If the robot light box doesn't stay aligned precisely North-South-East-West, will the software be able to correct for this when stitching without degrading the image?
(To minimize the need for mechanical precision and put the burden on computation would be nice.)
...Mike
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
Ed Kelsey
Why not build your own car? This is really a ridiculous idea if you ask me.
Thousands of people build their own cars every year, to get something better/different than what a manufacturer offers. Superperformance is the leader in this. A fully crowdsourced car is the new LM Rally Fighter, where you go to the factory and help build your own car. http://www.rallyfighter.com/buy-a-rally-fighter. Factory Five and Solidworks had a crowdsourced design project as well for a less expensive car. http://grassrootsmotorsports.com/design/
When international conglomerates don't build what is needed, slightly crazy people find a way.
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Re: Making a New Modern Drum Scanner
Quote:
Originally Posted by
jp498
Thousands of people build their own cars every year, to get something better/different than what a manufacturer offers. Superperformance is the leader in this. A fully crowdsourced car is the new LM Rally Fighter, where you go to the factory and help build your own car.
http://www.rallyfighter.com/buy-a-rally-fighter. Factory Five and Solidworks had a crowdsourced design project as well for a less expensive car.
http://grassrootsmotorsports.com/design/
When international conglomerates don't build what is needed, slightly crazy people find a way.
Nothing new about that....http://www.flickr.com/photos/michael...os/3380579654/
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Re: Making a New Modern Drum Scanner
Let's talk about goals. Here are some suggested ones:
1) High Quality, with the resolution of a pro flatbed but greater dynamic range.
2) Low price.
3) Ease of construction.
4) Ease of use.
5) Scalability.
The targeted user would be people like us: Film using photographers who can't afford or justify buying a good drum scanner.
I'll build a prototype using a PB-4 bellows, 80mm Rodagon, Portatrace light box, Nikon D200, because that's what I have.
It will be a table top device. There will be a camera support structure made out of wood, basically a thick beam supported by columns on both ends, like an upside down U. The PB-4 macro rail will be bolted to the cross beam. The light box will sit on the table underneath the support structure. Above the light box, there will be a thick piece of glass. I'll build a frame for the glass, such that three bolts can be used to adjust it's alignment. [The bellows will be aligned by pivoting it on it's mounting screw, and then the the glass table will adjusted to be parallel to the front of the lens. I'll use a Screen clam shell negative holder, which will be set on the glass, and various opaque masks will be used.
Some of the quality bottle necks will be:
A) The precision of the bellows, i.e. is the front perfectly square to the back.
B) The lens. Unfortunately, I no longer have a quality 50mm enlarging lens, at least I don't with a 39mm thread. I do have a bunch of other medium format and large format enlarging lenses, but I expect that the best performance would be with a 50mm f2.8 6 or 7 element design. My 80mm Rodagon, a fixed aperture lens, was designed, I think, for best performance at 1:1, which should be pretty close to what we need for LF scanning.
c) My ability to focus. Unfortunately, my D200 doesn't have live view, especially the ability to use live view while tethered to a computer. This would be a good use for D90 and D300s, as they allow live view.
d) The light source is visibly uneven, but we only need to use a small section of it. It should be good enough for a proof-of-concept.
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Re: Making a New Modern Drum Scanner
Do it!
Just wondering...what bellows are available for Canons?
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Re: Making a New Modern Drum Scanner
There are two types of Canon bellows, with and without circuitry for the aperture. The former is pretty spendy and available from B&H. Latter is less than $100 and can be found on Amazon. I'll be testing a macro lens so I don't need bellows up to 1:1 and have extension tubes for slightly over that. If you do go with bellows you can pick up an old Micro Nikkor and use with an adapter, or use a microscope objective as previously described. q.v. photomacrography.net for good info.
At 1:1, using a 30% overlap, with a sensor in a Canon 7D, I'd estimate it would take about 80 exposures to cover a single 4x5. That seems like oversampling a tad. Raw is 14 bit. I haven't tested my macro lens yet to see what resolution to expect.
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Re: Making a New Modern Drum Scanner
Oh boy, 80? That would almost be as tedious as making a profile with a Spyder3Print! Hopefully, the needed amount of sampling sites will be lower.
Macro lenses are also a good idea. I do have a couple of Nikon ones, a 55mm and a105mm, and I can test those as well.
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Re: Making a New Modern Drum Scanner
Transferring a portion of a transparency to a sensor through a macro lens has been done by many people including me. It is a sort of academic exercise now in that it can be done at high resolution with a top quality lens. The lens is the limiting factor in the detail that gets resolved. The choice is in the degree of magnification that one chooses. At 1 to 1 and smaller the resolution is set by the sensor. At higher magnification the resolution limit is set by the resolving power of the lens. As magnification is increased of course the field of view is decreased so more frames are required to cover the film. Even the best macro lenses will have difficulty in achieving an airy disc image as small as the 3 um or so that a good Aztec is capable of.
Of considerable interest is the type of back illumination that one might choose. That can be all the way from a diffused source to a highly collimated source. It only needs to cover the field of view of the objective if it moves in synchrony with the lens (as someone suggested above). A collimated backlight has the advantage of providing much less light scattering so higher contrast image transfer and more grain imaging than a diffuse source. An adjustable light source might be quite handy.
Dynamic range is limited by that of the sensor regardless of what is on film, until the film range falls below that of the sensor. For large film dynamic ranges one could employ digital HDR techniques already mentioned.
Nate Potter, Austin TX.