Originally posted by fiveseven Same as yours, with M42 adapter. Same year as well.
Ah, cool!
So does yours have the Nikon protrusions on the rear also?
When I first got mine, it had these.
And when I tried it on my K20D.
I couldn't tell if they were interfere ring or not with the mount.
However, this round, I decided to remove them(removed the ring, and filed them down). After which I mounted one of the thin M42/K mount adapters and to my surprise, the lens shot to infinity and the performance seemed improved.
Anyways, I've always found the K-5 to be tougher on CA and PF.
But this lens seems to be very good on the K-5.