Pentax 67 SMC 75mm F/2.8 - Are you shooting one of this?

[mindthemix]

Dan,

I followed your suggestion and carried out some basis testing, shooting a test chart at different apertures and found the following results.
At F2.8 sharpness is disappointing. It takes F8 for optimal performance (sharpness and micro contrast) while F5.6 is very satisfactory, being almost equal to F8. At F4 the image is blurred. I will repeat the test to be certain of that specific aperture and to expose at small apertures .

I used a Slik Pro 500DX tripod at its lowest position to prevent vibration, at my P67II I used mirror lock-up. Film was FP4+, semi stand developed in Rodinal 1+100 for 1 hour.

Jos.

My real-life testing with this glass. All handheld @ F/2.8 and F/4 - Tri-X 400

 

[DREW WILEY]

I should have bought one of these lenses when they were new and affordable. It's very hard to find them now. That extra speed would make
focusing a lot easier, esp for handheld work. The lens has been seriously tested on a far more objective basis than this thread .. so I'd take some of the previous remarks with a grain of salt. It should be deadly sharp just one stop down. I work primarily off a tripod, so for my budget the 74/4 is adequate, though unless its being used at inifinity, I routinely use a supplementary critical focus eyepiece. The magnifying hood also gives better focus than the ordinary prism, but then you're looking down into it at the backwards subject. But I have a 105/2.4 as well, and a 165/2.8, which are quite bright for MF. My only serious question mark about the 75/2.8 concerns the hybrid aspheric element and
how well this might withstand temp extremes or fluctuations over the long haul, if you are an outdoorsman like me. I've seen separations even in all-glass lenses in places like high desert canyons where the temps can swing seventy degrees between day and nite.
lenses, and optically excellent.