Originally posted by stevebrot The proof for this one would be to attempt a mount of the Sigma lens on a legacy Pentax body. Clearances on many of those are VERY tight.
My wife and her dad go to a lot of local auctions and estate sales, and they frequently get collections of old camera gear, including many Pentax bodies and lenses. I keep or sell the good stuff, but most of it is fairly worthless and ends up going to Goodwill. A lot of the bodies they get are Pentax, so since this kerfuffle with the Sigma lenses on the K-1, I've been paying attention to the mount clearance on these older Pentax FF cameras. From what I've seen, the old bodies have gobs of room around the mount. I suppose it's possible there are some exceptions, but I have yet to see them.
Here's three bodies I just happen to have on hand right now: K1000 (1970's), SF1 (1980's), and ZX-5n (1990's).
As you can see, the K1000 has no overhang whatsoever, so you could mount a bazooka if it had a K-mount on the end. The other two have a very slight overhang, but there is still gobs of space around the mount. I have two of the offending Sigma lenses, the 85mm 1.4 and the 50-150mm f/2.8, and they both have a bunch of extra room around them on these bodies.