Originally posted by furby which do you think is generally better in terms of pure image quality? I want to start shooting with some cheap primes, but would hate to constantly switch from bayonet to m42 mount. So I would like to stay with one mount. Any advice would be more than appreciated.
One thing to consider besides the changing lens designs over the years (the really great Pentax lenses are spread across the entire range) is the gradual improvement of the coatings as time passed.
An A 50/1.4, besides having a slightly tweaked lens design versus the M, which was a totally new design from the Tak and K 50's, also is said to handle flare better than the older lenses, and to let a bit more light pass through the glass.
I think it's all very subjective - a good photographer can get great images from virtually any coated Pentax lens. As far as changing lenses constantly, if that is an issue, the traditional advice (Mike C. to the contrary
) is to buy an adapter and one Tak to use just for fun - then standardize on K mount.