Originally posted by flyznest I recently rescued a Nikon 180mm f:2.8 ED AF IF lens from a junk pile(a freebie). All of the elements are still there and the lens is in fantastic shape. not even a scuff... but... it was used in some sort of an instrument at some point and for some reason all of the electronics were gutted. mostly what I am into is astrophotography so this would make a perfect lens... if I can get it to fit
I have heard rumors that you can mount this directly on the pentax mount and it kinda fits... but... I don't trust that this would be sturdy enough. i looked at the lens mount adapters but they all use an ~1.5x corrector and I really want to stay at f:2.8. Is there a way to just replace the nikon mount with a pentax mount? has anyone had any luck with this?
I have converted lenses for both Nikon AI and Minolta MD mount to K mount with stop down aperture.
Basically what you need is a K mount flange, either from a doner lens or by using a flanged M42 to K mount adaptor.
Doner lens mounts simetimes work better because they are thicker, and it is easier to countersink the screw heads, M42 - K mount flanged adaptors are only 0.8mm thick. I usually need to file th escrew heads a little so they don't scrape my body side mount.
the Nikon lenses have longer regestration distance also, so the thicker the doner mount the better. Never tried making the aperture coupling work