Originally posted by UncleVanya I’ve never noticed poor results at 20-24mm. I even used it on my Sony A7R3 on a manual adapter. I found it had a lot more geometric distortion than I expected but otherwise seemed good.
My experience is in line with this old review on Optical Limits:
Pentax DA 12-24mm f/4 AL ED [IF] - Review / Test Report
"The center quality decreases slightly towards the long end of the zoom range. At 24mm it is advisable tostop down a little to lift the contrast level and to get a little extra kick in terms of resolution."
Using the lens on a K3 with 24 MP surely didn't help
Taking the FA 2/24 instead was a real relief. BTW, the 2/24 is a great lens on APS-C, much more satisfying than of FF, just stop it down to 2,4 instead of wide open. Then at 5.6 it is unbeatable. Really profits from the sweat spot effect.
Why did you put that 12-24 on a Sony a7RIII? It is very much not FF compatible, I think even at 24 mm there was trouble when I tried it on my MZ-S.
---------- Post added 02-12-22 at 12:16 PM ----------
Originally posted by MikeStnly Here is an interesting thought - use the 1.4x T.C. - I just read that I can use it on the 77mm Limited. On the K-3iii that gives me a very small 161.7 mm telephoto.
I'm going on a trip by air at the end of March and was just bringing three limited primes - 15mm, 31mm and 77mm. I would like a long lens like the DA*300mm because there will be birds where I am going that I can't at home, but I don't want to carry it.
The T.C. won't work on the 15mm, but with my crop sensor I can in effect add two more lenses. The 31 will double as a 65mm and the 77 as a 161.7mm. If I throw in my 40mm Limited, I would also have an 84mm. So four small lenses and the converter - letting me cover from 15mm to almost 200mm. That should cover all my needs in a very light package.
Rather don't use a TC with wide angle lenses. With the 77mm is might be OK, but generally speaking you will more often than not get better IQ by just cropping the picture afterwards. With 26 MP at your disposal this will rarely be a problem.
If you want a really great 200mm equivalent for APS-C, get the old FA 2.8/135. A little hard to find, but absolutely worth it. Tiny in size also because of its retractive hood, sharp as hell wide open, not extending due to its IF, great bokeh and colours. They should reissue that lens in a modernized version!