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02-08-2010, 06:59 AM   #1
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Lowell Goudge's Avatar

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Nikon to pentax adaptor

I got this before christmas, but had little time to evaluate it fully.

this is an optically corrected mechanical mount interface.

By optically corrected, there is a lens group in the adaptor that allows retention of infinity focus, even though the adaptror is approximately 12mm thick.

The adaptor accepts Nikon AI lenses, and they function in stopped down mode only (like M42 lenses)

The optical correction provides a 1.25x magnification (i.e. like a teleconverter) as measured by comparing the field of view using a Tamron adaptall 2 lens on the same camera with both nikon and pentax mounts and the adaptor when using the
nikon mount.

Exact magnification was done by counting the linear pixels differences between 2 points in the photos

edit note, the image looses something in posting it looks much better in an image editor

The magnification will aslo result in approximately 1/2 stop change in exposure as well.

the shot below is one of many taken with my K10D and the adaptor along with an AI nikkor 50mm F1.8 (kit lens from a Nikon FE)

overall focusing and contrast was very good with no real loss of sharpness even at edges.

for ~$40 this is not too bad an adaptor, but due to magnification is really only of use on normal to tele lenses.

I personally would prefer to change the mount on a wide angle to keep both the speed and focal length, but the 50mm lens with adaptor turns into a fairly fast 62mm lens which is an interesting focal length, considering the ASP-C crop factor as well, it is the equivelent to a 100mm portrait lens.

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02-08-2010, 01:52 PM   #2
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Thanks for the review. Looks decent, especially for the price.

A quick question -- do you see any relatively simple way to remove the optical correction lens? I have an old manual Nikkor macro lens that I enjoy, and I currently mount it directly to the camera (loosely and upside-down, as that's how it fits).

Anyway, if the glass comes out, it would be nice to turn that old macro lens into a K-mount. The extra length of the adapter wouldn't bother me.
02-08-2010, 01:57 PM   #3
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Original Poster
the issue is that if you do this, the adaptor becomes a 12mm extension tube. I think removal would be simple but if you do a search on teh internet for the company that sells them, I think they also sell one without correction
02-08-2010, 02:04 PM   #4
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what a timely review, thanks!!!
I was thinking about getting one of the AI to k-mount adapter with a lens to correct infinity focus since I just acquired a Chinon (Tomioka) 135mm 2.8 for Nikon AI mount and I want to test it out on my K10D. I also ordered the AI to m42 mount to see if it will work better.

02-08-2010, 02:07 PM   #5
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QuoteOriginally posted by Lowell Goudge Quote
the issue is that if you do this, the adaptor becomes a 12mm extension tube. I think removal would be simple but if you do a search on teh internet for the company that sells them, I think they also sell one without correction
That is interesting.... I know the AI to m42 adapter does not have the glass element, I haven't found an AI to K adapter without glass yet.
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