Originally posted by Zephos I refer to this chart a lot and thought I would share it. Maybe it should be a sticky in the forum for all the newbies like me. Really good info.
There is an error in terminology in that table. The heading "Auto-Aperture" is incorrect and should instead be "Allows Shutter Priority" (exposure mode on the camera body). All of the lens series in that column except M and K have the electrical contacts on body to allow the camera body to manipulate the iris (aperture), which may be necessary to achieve correct exposure if the photographer has chosen the shutter priority exposure mode on the camera body.
The term "auto-aperture" means that the lens iris is wide open during light-metering but is capable of automatically stopping down to the aperture chosen by the photographer or the auto exposure mode (aperture priority, hyper-program, or manual) upon tripping the shutter. All of the lens series in the column headed by "Auto-Aperture" have auto-aperture (as well as most of the SMC Takumar screw-mount lenses). Before auto-aperture was invented, the photographer would open the iris to the widest aperture, focus, then stop the lens down until the light-meter indicates correct exposure.