On Dec 13, 2005, at 10:45 AM, David Oswald wrote:
... An SMC Pentax-M lens doesn't support AF nor does it have an
auto-diaphragm. In other words, it doesn't support auto aperture.
Mounted on one of Pentax's DSLR's, you have to jump through an
extra hoop to get it to meter for you. Many people here don't see
this as a big deal. YMMV.
Previous to that, Pentax had SMC Pentax and Pentax K lenses.
They'll work about the same as a Pentax-M lens. ...
David,
All Pentax K-mount lenses (including M series) have an automatic
diaphragm mechanism.
What the pre-"A" series lenses are missing is the "A" position on the
aperture ring and the electronic contacts needed to communicate with
the *ist DL for fully automatic exposure. With these lenses you use
the aperture ring on the lens to set the desired lens opening, set
the body into Manual exposure mode, and press the AE-Lock button
(Green button on the D model) to meter a scene.
If you want pretty much full functionality, get an SMC Pentax-FA
50mm f/1.4 or f/1.7. The SMC Pentax-F 50mm f/1.4 or 1.7 is
essentially an equally acceptable alternative.
I agree with that. And, if you are happy enough with Manual focus, an
A series 50/1.4 or 50/1.7 works very well too. But I would strongly
recommend the Pentax FA50/1.4 anyway ... I find this to be a superb
lens for both manual and auto focus operation, with top notch image
quality, resolution and contrast.
Godfrey
