so you say that we could replicate any full frame design? and for example make super fast 35mm tessar? im not sure because we would already see all that in movie industry that already use half frame in 35mm movies, and also we would see it in many half frame cameras before...
and one edit to.make it clear- if lens is 35mm yes field of view will be normal on aps-c but all problems that wide angle have will stay-like distortions and all - you wont get portrait lens realistic perspective with 35mm if you use it on 4/3 and has FOV of 70mm you will basically have just middle of wide image kn your sensor .
Originally Posted by retinax
No, teiterate: a 35 for aps-c is not a wide. Maybe stop thinking in terms of focal length, think in terms of angle of view. A 35 that's made for Aps-c could be the same design as a 50 for full frame, downscaled. It doesn't need to cover full frame, therefore it doesn't need to be wide-angle, unlike a lens of the same focal length that is for use on full frame or larger. And there you have the answer to why these 35 mm lenses for aps-c can be sonnar designs, very fast etc. They do the same thing a 50 for full frame does, in terms of angle of view, and projected image, and can thus be of the same design.