Advice for getting 5:1 on APSC sensor

[ChrisR]

No, but I don't think there's anything odd there. The "morfanon" - a simple achromat which was tried early on as a tube lens, has a slight telephoto construction which reduces the distance. Likely there's no reason why that shouldn't be true of others.

[rjlittlefield]

One set up that has intrigued me is this one by Craig Gerard:
http://photomacrography.net/forum/viewt ... 5d814673a8

I like the low profile of it, but am a bit confused by the use of the SK unifoc and the relatively short distance between the objective and sensor - it does not appear to be 200 mm.

Images #1 and #2 on that page, showing an objective mounted, have the caption "Objective > Iris > Nikon MXA20696 tube lens inside SK housing > Schneider Kreuznach Unifoc 58 > Nikon PN-11 > Novoflex Nikon to EOS adapter."

Image #3 also shows an objective mounted. It has a similar caption, "Objective > Iris > SK Unifoc 12 > Nikon MXA20696 tube lens inside SK housing > Schneider Kreuznach Unifoc 58 > Nikon PN-11 > Novoflex Nikon to EOS adapter". That is different from the previous caption only in the addition of "SK Unifoc 12" behind the iris.

The tube lens in each case is the Nikon MXA20696, which definitely does have a slight telephoto design, as shown in this diagram from the Technical Information tab on its description at Edmund Optics:



Note the dimensions, only 151.2 mm from the rear of the tube lens to sensor, 180.2 mm from the front of the tube lens to sensor, for a 200 mm lens.

In evaluating Craig's photos, notice also that these various images show different extensions on the SK Unifoc. Only one setting of the Unifoc will produce the perfect infinity focus for the tube lens. The other settings are modifications that will give different magnifications and probably work OK given the relatively low NA of the 10X NA 0.28 Mitutoyo that is shown.

--Rik

[Davids]

Very interesting. I hope I don't frustrate you all with my lack of knowledge in optics. All of your responses have been extremely helpful and eye opening! I think, for my purposes, I'll stick with using a Nikon AI-S 200mm adapted for my fuji as a tube lens. Of course, now I just need to find the Nikon 200mm in decent condition!

[Chris S.]

David,

I'll stick with using a Nikon AI-S 200mm adapted for my fuji as a tube lens. Of course, now I just need to find the Nikon 200mm in decent condition!

That's a solid approach. But be aware that while an AI-S lens will work just fine in your implementation, you can save money by buying an even older Nikon lens such as the non-AI lenses I suggested. AI-S lenses are immediately usable on current Nikon bodies, so they command a higher price than non-AI lenses, which need to be converted or used on an adapter. Since you are going to use an adapter, the AI-S mount gives you no added benefit. This assumes that your adapter is OK with non-AI lenses; the one I linked to is, but I don't know if they all are. But all this said, Nikon AI-S lenses are still a very good value, and are probably easier to resell.

--Chris