Originally posted by ChristianRock Ah yes. The lens you have is known to be a Pentax design failure. So, nothing lost by taking it apart and playing with the glass What do you do with it? I ask because I have a 2nd SMC Pentax-A 70-210 that I bought with a K1000 a few years ago and when I got it out of the bag it came apart in my hands. It's part of my desk decoration at work, but I wonder what else I could do with it.
The idea was to use the 100-300mm carcass plus bits and pieces from my collection of salvaged lens elements to frankenlens something interestingly funky together. So far the best I've managed is something with about a 400mm focal length that's reasonably sharp in the centre but just a swirly blur around the edges.
Actually, this discussion about 100-300mm lenses has made me want to put it back together with the original elements for another try. Maybe with everything cleaned and tightened up inside it'll give better results. I could also put in a limiter to stop it zooming all the way to 300mm, which is where it's worst. I seem to remember that it was actually okay up to about 275mm, then the sharpness fell off a cliff.
Edit: I'll add a sample of the 400mm-ish frankenlens version, which is certainly funky but not really in a very fun way. The lens was never designed to be taken apart then put back together again, so if I do reassemble it it'll be missing some features that I don't really want anyway. You know: autofocus, autoexposure, that sort of stuff.
Last edited by Dartmoor Dave; 07-09-2018 at 02:35 AM.