Originally posted by normhead So if there aren't any "true Apo" lenses, then, back to the pinhole.
Hahaha, believe it or not, when I switched to full digital from large format for lack of darkroom, the first thing i wanted to buy was a lens cap with a laser cut pinhole!
It never materialised...
I would like to believe that there are no Apo lenses available for PK, but there are a few that can be leitax'ed (Leica Apo's are not impostors; plus the likes of the Apo Planar, Apo Sonnar, etc.). A pity my wallet is already crying loud
AFAIK the 50mm and 100mm macro made by Pentax are "almost" Apo. Pentax correctly does not market them as such, though the fringing is minimal.
For the patient fellows who stack ultra macro shots with special (or microscope) objectives there is an ample choice of true apochromats.
All in all, I'd say that there are ways to shoot with a true apo, making use of some ingenuity and investing some good money.
Though in theory you are perfectly right: pinholes are not affected by most optical aberrations, and on top of that the DOF is incredible... if only we could magically get rid of diffraction!
JUST A THOUGHT:
I am quite surprised that most of those who actually care about border to border sharpness, flat field, and zero CA have never tried to experiment with repro lenses. Most of them were called Apo (Apo Geronar, Apo Tessar, Apo Skopar, Apo Ronar), and those that were not sold as Apo had more or less the performance of the others (like the G-Claron, Repro-Claron and Repromaster).
Unfortunately the speed was very low, and most of them had long focals. The only ones I know under 150mm are the Repromaster 80mm and 135mm, and the Repro-Claron 135mm and 55mm.
The low speed was a big problem with an optical viewfinder.
I have seen a few incredible contraptions used as poor man's long tele. Not much more.
No surprise it was not a very popular solution for other applications.
Now with Live View it should me more doable. A simple adapter ring and a set of ring/bellows is all is needed.
Instead of a very long focal, one of the shortest ones could be used for table top and macro photography.
Sharpness on a high density sensor should not be top notch anymore, but all the other pros should still hold true.
I would be curious to see the result, if anybody ever decides to give it a try.
Maybe it's not as silly an idea...
Last edited by cyberjunkie; 09-30-2018 at 10:22 AM.