Quote Originally Posted by benjiboy View Post
There's actually very little in the difference between them because they are nearly equal in distance from the diagonal measurement of the 24x36mm frame is 43mm which should be the ideal focal length to approximate human vision.
I shoot most often with pentax 43mm prime and I find it the most natural of all my lenses on 35mm cameras. I also like my 40mm Rollei 35se, even though it's not an slr, the focal length feels just right.