Originally posted by wtlwdwgn Wasn't Pentax also the first to have an automatic diaphragm in the lenses?
Depends on what you want for "automatic." Exacta lenses had a button that sat over the front-of-camera shutter release. As you pressed, the diaphragm closed gradually to the pre-selected stop before the shutter was released, then the diaphragm opened as you raised your finger off the button*. Alpa used the same type of mechanism, but I'm not sure that Alpas were introduced before Pentax. The first model "K" Pentax** had an "automatic" diaphragm with a lever on the lens that had to be cocked back, then when the shutter release top right of camera was pressed, a pedal-like device hit a pin releasing the cocked diaphragm lever which would snap shut very quickly before the shutter went off. The lever had to be re-cocked for each shot to keep the diaphragm open.
The immense success of Pentax in the late 50's through the 60's resided in the basic, user-friendly layout of controls: right-top wind lever, shutter, release and shutter-speed dial; rewind crank; instant-return mirror; long mirror preventing edge loss with long lenses; and a finder brighter and easier to focus than any on either an SLR or a reflex housing,
*Exacta cameras had a number of odd features other than the front-mounted, press back shutter release. There was a wind crank on the left that operated from the front of the camera around toward the back (operate with left index finger), and a built-in film cutting knife so you could snip off some or all of the film without rewinding into the cassette. Exactas also had an extended low speed dial, up to 30 seconds as I recall.
**Model "K" Pentax had the cocking diaphragm, the concurrent model "S" was strictly pre-set or manual diaphragm. Early ads by Pentax had the two cameras facing squarely at you, one above the other, with the question: "Which Pentax?"