Originally posted by builttospill Obviously the difference is enough because Pentax currently produces the DA 15 Limited and DA 21 Limited; members of this very forum own both.
As we both well know, the difference between 15 and 21 is much larger (almost 40% FOV difference) than the difference between 31 and 35, which is in itself larger than the marginal difference between 43 and 50, and negligible difference between 77 and 85.of)
In any case, Pentax is one of the only companies that is (sort of) rethinking lens design for a crop sensor, but only sort of. Their lens line up does feel and behave rather arbitrarily (e.g., "true normal" for film - 43, but only "regular normal" for digital - DA 35,,, where's the 28?) I'm not sure why you would bother arguing this simple point. The oddball focal lengths exist partly to be oddball, because a lot of these lenses could have been designed at more traditional focal lengths... but they were not. E.g., the DA 21, which crops to approximately 31 mm, emulates their OWN oddball focal length, when they easily could have designed a super high quality 24mm for ASPC. But they think different, and produce a more expensive lens due to R & D and design limitations at the wide end in order to produce the only 21mm lens I know that is currently produced.