Originally posted by gofour3 Nope the manual focus A50/1.2 was the last one Pentax made. Must have been too expensive/difficult for Pentax to make a 50/1.2 AF lens?
Phil.
I suspect there are a few things standing in the way.
The first is technical, although the A50/1.2 did manage to put the A electrical contacts around the edge; however, fitting the screwdrive in without making the lens overlarge might have been an issue. f/1.2 is the fastest you can get a 50-55mm lens before you start to run out of room between the outer edge of the rear element and the inner edge of the K mount throat. This is why Canon can support an AF 50/1.0 and 85/1.2; their mount diameter is much wider.
The second is a matter of style; it's probably assumed that anyone using an f/1.2 lens is doing the sort of work where manual focus would be more than adequate.
The third is that it's really not needed any more, at least in terms of light-gathering ability; even a middle-of-the-road DSLR can do better at 1600 than most films could at 400 when the A50/1.2 was invented. You're better off giving a 50/1.4 a shorter minimum focal distance.
---------- Post added 25-07-18 at 20:12 ----------
Originally posted by monochrome Pentax people are accustomed to tiny f/4 pancake lenses on svelte APSc Cameras..
To be fair, the last 50mm f/1.4 full-frame AF lens that Pentax made was not exactly large (though having the motor inside the camera body does tend to keep the size down).
The only true test is to put three K-1's side by side with an FA50/1.4, a DA* 55/1.4 and a D-FA*50/1.4 mounted. Then at least we are comparing apples to apples.