Making a scanner with a DSLR

[Dr Klaus Schmitt]

I personally think it is a stripped down version of the Apo Rodagon D 75mm in 1x version!


1x version: http://www.macrolenses.de/ml_detail.php?ObjektiveNr=154
2x version: http://www.macrolenses.de/ml_detail.php?ObjektiveNr=253

I also have a f4 version of the same lens, so it seems to be common that Rodenstock made special, industrial versions of that one.
http://www.macrolenses.de/ml_detail.php?ObjektiveNr=123

MTF in comparison:



Full lens + MTF (also f5.5) data is here (n german): http://www.rodenstock-photo.com/medi...3-62__8225.pdf

.

[Peter De Smidt]

For the prices that used Rodagon D's are going for, this is a really good deal. Like Rick said, it'll make a fun macro lens even if this scanner thing doesn't work out.

I've been pretty busy with work lately, but I should have some time over the next couple of days to work on the scanner project.

[rob]

When I bought my apo rodagon-N 50mm, it was attached to a scanner CCD board. I have no idea what scanner it was in. I couldn't find any indications of the scanner brand from the board.

[argos33]

Ah blast must have missed it! Let me know how they work out!

[jm51]

This looks cheap enough to hack:

http://www.ebay.co.uk/itm/3208247157...84.m1439.l2649

[Peter De Smidt]

So while it may not look like I've been doing anything, something I frequently accused of, I've been working on a light source. It should be done in the next few days.

I've also been doing some research. Check out the unit for macro photography in the following build: http://www.photomacrography.net/foru...er=asc&start=0

Personally, I'd be tempted to uses bolts through the granite with nuts and washers instead of epoxying soft brass inserts in the granite, but the epoxied inserts are more elegant.

I would add some damping compound to the aluminum comment. (I almost said "dampening" to give Rick something to comment on )

[rdenney]

(I almost said "dampening" to give Rick something to comment on )

Rick "not seeing any need for watering this setup" Denney

[rdenney]

So while it may not look like I've been doing anything, something I frequently accused of, I've been working on a light source. It should be done in the next few days.

I've also been doing some research. Check out the unit for macro photography in the following build: http://www.photomacrography.net/foru...er=asc&start=0

Personally, I'd be tempted to uses bolts through the granite with nuts and washers instead of epoxying soft brass inserts in the granite, but the epoxied inserts are more elegant.

I would add some damping compound to the aluminum comment. (I almost said "dampening" to give Rick something to comment on )

Remember, these guys are going for 10x, while we are going for 1x. Their vibration concerns are an order of magnitude higher than ours.

I'm rather persuaded by the notion of tight coupling between the camera and the base system. The high-frequency damping and mass of the granite base should take the edge off shutter movement, and I would be concerned about any damped coupling achievable by mortals lacking the necessary avoidance of creep. But these guys are worried about stage movements of one tenth of one sensel, which is 0.6 microns for your 5DII, in order to maintain sensel accuracy at 10x magnification. With my 5D, I can maintain sensel accuracy at 1:1 by restraining the stage to 8 microns (+/- 4 microns). That would correspond to about 63 line pairs/mm (half of the 125 sensels/mm density of the 5D sensor). That's more than good enough for our purposes, it seems to me.

It would be easy for him to brace the top of his column with light rods to the other corners of his granite slab. That would decrease the magnitude of any vibration without inducing lower-frequency resonance.

More generally, I had a discussion with a friend of mine who is a computer graphics expert at a university. He showed me stitched graphics of microscope slides he is making for his wife, who is a research ophthalmologist at the same university. She is using slides made from tissues of retinal disorders, including macular degeneration. His stitches put together terrain that is in the 6mm range, and scales down to the sub-cellular level. High-end stuff indeed.

He suggests that evenness of illumination will be critical, because people can see macro repeating patterns very easily in an image--far more easily than seeing those patterns when they do not repeat. He believes we'll have a hard time weeding out those patterns. He agrees that our use of an enlarger-head light source might help, but he suggests that every component of the system (lens, sensor) will add falloff even with the most even possible illumination. Sure, we can correct that with software systematically, but that may take some effort to do, and it will need to be done before stitching.

He also thinks stitching will be difficult in large, flat expanses of tone. He does not think the grain patterns will provide the necessary detail to provide accurate stitches. But he thinks we are on the right track using software-driven stitch algorithms rather than attempting the mechanical precision necessary to avoid it--that imprecision will cause more artifacts that the stitching will, especially if we overlap more rather than less.

So, I think the next step for me is to experiment with stitching before moving on to big construction. But the light source will be a challenge. If I use an enlarger head, the heat will be a problem unless I get the source out from under the film, and that will require some creativity with a vertical arrangement and the camera looking down onto the film. I don't want to invest too heavily into solving the light source problem until I'm sure of being able to assemble the image.

Rick "waiting on the lens for now" Denney

[Peter De Smidt]

I agree that stitching is the big hurdle, and the only way to know will be to try it.

I've got a glass plate for the negative stage, and the test light source is done. Next, I'll build a holder for the glass plate that allows me to register an ABS guide for the negative carrier. Basically it's going to be a rectangular piece of 1/4" black abs sheet. Why? Because it's stable, opaque, and I already have some. I'll cut out a rectangle in the middle of the sheet, and I'll use two dowels to act as registration pins for positioning the guide on the glass plate. (The ABS will have two corresponding holes, and so when the ABS sheet is slid onto the dowels, it should be positioned in a repeatable way on the glass surface.) The cutout will be such that the entire negative can be positioned over the imaging area by sliding the carrier.

[Peter De Smidt]

The good news is that the Linos lens arrived today. The bad news is that I don't see any mounting threads.