I would imagine the advantages are rigidity, better alignment of sensor plane and focal plane, and better optical performance... Enlarging lenses are not required or expected to perform as well as macro lenses at 1:1.Originally Posted by Peter J. De Smidt
But there are some really great enlarging lenses, and I do think you could have very good results with a bellows unit on a DSLR. It just adds a level of complexity which is in my view unnecessary. Good 1:1 lenses are cheap.
This is straw-man nonsense. The whole point of this thread is that the vast majority of the R&D has already been done, and is continuing to be done, by the major digital camera and sensor manufacturers. Getting the details sorted is likewise also in progress by high-end professionals. To wit, see the article The Future of Scanning by Willam Blackwell at The Agnostic Print. A quote below to whet appetites; see the article for the gory details:
Acknowledged, this is "merely" for 35mm capture. Nevertheless, that's all that's needed to prove the principle. The rest is a fairly boring matter of engineering. Depending on how good the copy camera is, the need for a scanning-stitching station may also go away (see the article for more on that as well).I’ve recently built such a system for the University of Vermont Slide Library. Where MIT spent many “cutting edge” years hand-scanning every slide in their archive, we hope to digitize our 150,000 slides in under three months (pre metadata inclusion) with only $3400 in equipment. That is all made possible by the full frame pro dSLR.
See post #2 of this thread and then post #1 of this thread for the source and direct your complaints there.
Ben, which ones do you have in mind? I agree that avoiding a bellows is a good idea, if the requisite magnificantion/quality can be gotten by other means. I have a 55mm Nikkor 2.8 P Auto. It'll go to 1:1 on it's own, but it is optimized (according to online discussions) for 1:10. I'll still give it a try.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I've been using the Sigma 50/2.8, and it's fantastic at 1:1 and ƒ/8... I bet the 55 Nikkor is similarly great—I wouldn't be surprised if the bit about it being optimized for 1:10 is just an internet yarn. Extreme corner performance is not really an issue, because you'll be overlapping frames anyway. You're throwing away all of your corners.
All of these macro designs are able to be much better corrected than general purpose lenses, because no one expects them to be faster than ƒ/2.8. The lens designer's ƒ/1.4 handcuffs have been removed. (It's strange that in an age with zillion megapixel cameras, great ISO 3200, and highly advanced lens design software, lenses keep getting faster rather than better. I would love to have a Canon 35mm ƒ/4 with an asphere or two. It would be the smallest and lightest SLR lens, but far and away the sharpest. But I digress.)
Hi Ben,
That sounds reasonable. Since one of the major reasons for this project is affordability, looking at extremely expensive (and rare) lenses doesn't make much sense.
I've been reading about microscope eyepieces. See, for example:http://coinimaging.com/Lens_tests.html He ends up mostly using micro Nikkors for his own photography. In addition, according to http://www.microscopyu.com/articles/...tivespecs.html, "Microscope objectives are usually designed to be used with a specific group of oculars and/or tube lenses strategically placed to assist in the removal of residual optical errors." While some of the newer ones might be fully corrected, there's no guarantee that they'll be better than the standard macro lenses in our application. (If someone has some of these, by all means test them.)
I'm going to test my 55mm Nikkor, which appear to be common and available for $100-150, and I have a reverse adapter on the way to see if that helps. (They're about $3 shipped on Ebay.) I'll also test a componen-S 50mm, but I'll have to make a custom mount.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I've had some correspondence with an expert on macro lenses. He built just the type of system we're suggesting for a client. Although he can't share details, both he and the client were very happy with the results. He said that he's not a big fan of microscope objectives "...as their projected image is rather small (18-20mm), need long tubes (160-210mm) or additional hard to find tube lenses (for infinity corrected objectives) and the biggest problem is their very shallows DOF, so each ever so slight non-planarity of your film kills the result."
I've been thinking about how we should attach the camera to the support structure. If we use a macro unit with bellows that allows camera positioning, that's fairly easy, but if we want to avoid bellows use, we'll need a way to accurately position the camera.
My idea is to use a cheap arca compatible clamp and nodal slide, along with an inexpensive camera plate. The clamp ($30 or more) would get bolted to the front of the support structure in a vertical direction.
[Pictures used with permission]
This would allow the Nodal slide, such as http://www.ebay.com/itm/SUNWAYFOTO-D...item53e9701d5e, to move up and down in the clamp.
We could adjust the clamp around the bolt axis, perhaps using set screws along the long edge of the clamp, one near the top and one near the bottom, to allow fine adjustments. To adjust the camera tilting front and back, I plan on having bolds in threaded holes at the bottom of each of the legs of the support structure.
The issue left would how to very careful adjust the position of the camera plate in the clamp. This would be used to move the camera closer or farther from the film. There are some very expensive lead screw focusing rails, such as: http://reallyrightstuff.com/ProductD...ng-rail&key=it, that could replace the slide and clamp, but they're pretty expensive. My idea is to use a threaded rod (bolt, knob, ...) in a block bellow the clamp. Turning the rod will move it up and down. If it is situated so that mates against the the front of the nodal slide and it clears the clamp, it could be used to adjust the position of the slide in the clamp quite precisely.
Does that sound reasonable? Suggestions?
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I have a device that allows x/y positioning of a camera mounted on a tripod. Looks like it could be used to move a stage around in the x and y axis. Hand operated though. Is there an end goal of an automated solution? Seems like you'd want autofocus working for that, so a macro lens (and tubes if more mag needed) would be the most likely lens setup.
Hi Jim. Yes, there's an end goal of automation, but I don't think we'll need auto focus. Instead well keep the negative very flat, using a clam shell holder, and move the holder on a very flat surface, i.e. a sheet of thick glass.
Hi Mike, that's exactly what I had in mind.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I realized after I posted that you'd pretty much covered what I said so I deleted my post.
Anyway, here's a cheaper focusing rail, but it's got the unnecessary extra direction of movement. And here's a real cheap one.
...Mike
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