Great tip, I'll keep it in mind...
I don't have any EOS lenses, so I'd get the pk-m43 adapter.
There's one that has an open and lock feature like the FD adapters. Do I need to get that one or would the simple one that only has the eject pin work?
Thanks!
I used EOS based adapters for about 4 years before getting any EOS lenses. Even now the only EOS lenses I have are never used. I got 2 film era kit zooms as part of a job lot. Free is about right on their value IMO horribly soft & with their electronic controls a pain to adapt.
For an A series lens as you linked to a simple adapter should work fine.
For the sake of completeness here's a quick run down of the main Pentax lens types:
M42 a screw mount that predates the PK bayonet, very popular in it's day and also used by many other manufacturers. Later versions had an automatic stop down function via a pin in the base of the lens.
K & M series were the first bayonet lenses Pentax made, just using the standard PK mount. It was designed with backwards compatibility with M42 in mind, Pentax selling an adapter that clipped into the mount on the camera & converted the bayonet to M42. Again popular with other manufacturers.
A series added electrical contacts to the mount allowing the camera body to control aperture (This coding tell the body the lenses widest aperture & how far it stops down) This revised mount is called PKA, there are again numerous third party examples.
F series add auto focus via a screw linkage to the PKA mount. (Note Ricoh's variant of the PKA mount 'RK' has a pin that can catch in the AF drive.)
FA series were similar to F series but provided a bit more information to the camera. Not all had aperture rings IIRC (it may only be the rarer FA-J lenses)
DA series are made for APSC digital cameras they lack aperture rings & rarely cover full frame.
DFA are digital lenses that do cover full frame, earlier ones being for film & digital but now in production for the K1. I think these are again without aperture rings.
I don't personally have any of the K, FA or DFA series lenses.
All of these are adaptable via a PK adapter (but loose camera controlled functions). Other than possible lack of aperture control & coverage issues for full frame users all of the PK bayonet variants are the same when it comes to adapting.
The same M42 adapters Pentax made for the K series cameras still work with all K mount hardware.
