We've all been there, Toralf...:-) The M and the K are functionally the same. The K series predates the M.
The F-series were the first generation of autofocus lenses. It differs from the FA series in that it doesn't have a chip on board to inform the camera about maximum MTF aperture and lens identification. Others are the Limited, which I'm sure you know of ;-) and one peculiar lens designed for the MEF camera. It's an early autofocus design with the motor and batteries inside the lens. It's a 28-70/2.8 zoom lens, but I don't remember it's exact name. There are some other designations too, like the asterisk (*) that alledgedly denotes use of special quality glass. At the prices of those lenses, they damn better have some special glass too...:-). The asterisk can be found on both A, F and FA series lenses. Jostein Toralf wrote: > And now a question that will reveal my status as a complete novice: > > What exactly do the different letters in the Pentax lens designations > mean? I've been looking for an explanation on the K mount info page and > other places, but not found anything... > > I understand the difference between an "M" and "A" lens, of course, and > I know an "FA" lens has autofocus. But how about "F"? Or "K"? And are > there others? > > - Toralf > >
