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02-13-2008, 10:49 AM   #1
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P67 lenses on K10/K20

How well do the P67 lenses work on K10/K20 bodies? Currently I shoot mostly 4x5 for landscape work but am considering using a K20 body with my P67 45, 135 and 200mm lenses when I don't have time to set up the Arca-Swiss. Image quality is paramount as is the ability to print my images to at least 20x24. Do the images made from these lenses compare in quality to the digital lenses made for the K10/K20 bodies?

Also, as I understand it, the 3 lenses that I mentioned above would become approximately 68, 200 and 300mm lenses on the digital bodies, right?

(If Pentax is listeniing, I also would love to see a Pentax medium format digital.) Thanks all.
Don Boyd Photographs

02-13-2008, 11:29 AM   #2
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QuoteOriginally posted by Don Boyd Quote
Also, as I understand it, the 3 lenses that I mentioned above would become approximately 68, 200 and 300mm lenses on the digital bodies, right?

(If Pentax is listeniing, I also would love to see a Pentax medium format digital.) Thanks all.
Don Boyd Photographs
No, the lenses remain 45, 135 and 200mm

what is different is the field of view.

compared to your 6x7 the lenses when used on an ASP-C sensor have the field of view of 145, 430 and 640mm
you are correct when compared to the field of view in 35mm format, that they have the same field of view as 68, 200, 300mm
02-13-2008, 11:36 AM   #3
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Lowell, thanks for the clarification. As I move from analog 4x5 to digital I realize I am in a foreign country where the language while it may sound the same is indeed foreign.
02-13-2008, 11:05 PM   #4
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I have never used MF lenses on cameras with APS sized sensor (although if someone figured out a way to use mamiya lenses on a K10 then I'm all ears...) although I have been told that the resolving power/performance of medium format lenses is generally lower than equivalent lenses for 35mm/APS. I guess this is because of the advantage in size of the 67 neg compared to 35mm neg. - the 35mm lenses need to work harder to achieve good resolutions.

I'd take this with a grain of salt because someone out there could probably point to the fact that Zeiss MF glass is probably some of the best ever made, and Pentax 67 glass may also compare well with its FF/APS brethren. I recall lenses for the Mamiya 7 rangefinders topped 100 lines per mm.

Lens resolution test on the net may yield some interesting results, but better still some real-world tests would be interesting to see! I think Pentax 67 to K mount adaptors are freely available on fleabay (again, I've never used them but make sure they allow lens focus to infinity).

02-14-2008, 04:49 PM   #5
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QuoteOriginally posted by beekala Quote
I have never used MF lenses on cameras with APS sized sensor (although if someone figured out a way to use mamiya lenses on a K10 then I'm all ears...) although I have been told that the resolving power/performance of medium format lenses is generally lower than equivalent lenses for 35mm/APS. I guess this is because of the advantage in size of the 67 neg compared to 35mm neg. - the 35mm lenses need to work harder to achieve good resolutions.
I was under the impression that the lower resolution of the medium and large format lenses was a compromise by the lens designer who has to cover a much larger image circle with the lens. Getting 110 lp resolution across a 6x7 cm field is much harder that on a 24x36 mm field.
02-15-2008, 12:22 AM   #6
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This website might be of interest.

Medium Format Cameras - Testing Lenses

the pentax 105mm achieves max 76 lines/mm at f5.6.
I know its wanky to fuss over lines/mm while ignoring all the other characterstics of the lens, but I'd imagine that 60-80 lines/mm seems to indicate a reasonably sharp lens.

BUT check out the mamiya 7 rangefinder 80mm. Awesome figures.

Also the Rolleiflx 2.8 Schneider....I've got one of these but dammit the lens has got BAD cleaning marks and fungus...such a shame.https://www.pentaxforums.com/forums/images/smilies/eek.gif
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