As I have now completed the conversion of the Ilford Monobar I have now gone back to converting another lens. The Monobar converdion was described in its own thread (Here:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/80872-ilford-m...onversion.html) but since it was mentioned in this thread a photo of the completed camera is shown bellow. I'm not sure if this counts as an impossible lens, camera or bellows convesion, but it was fun to do and will be fun to play with when the weather improves.
The latest conversion is a Vivitar 55mm f/2.8 macro, originally in Konica AR mount. I know that this lens is available in K mount but I got it so cheep that I though it was worth a try in spite of the potential difficulties of acheiving infinity focus from a mount with a registration distance 4.8mm shorter than K mount.
The conversion involved dismantling the lens, removing about 4mm of metal from the back of the lens mount and the aperture ring, machining a new recess into the back for bits of the aperture mechanism, drilling and tapping new holes and fitting a flanged M42 adapter. So that I didn't have to stop the lens down before taking a picture I made and fitted a new aperture actuating lever so the lens workes as an M lens as the original K mount version did. It also reaches infinity focus.
As with previous conversions, I had a go at making it an A lens as can be seen from the photo. Unlike most of the previous lenses, in this one the aperture mechanism provides a linear change in aperture area with lever movement so I was hopefull it would be more sucessfull than previous attempts. However the aperture lever movement of the K AR lenses is greater that K mount. At the wide end it was OK but at the smallest aperture the exposure was almost 3 stops too high so I took the A pin out again and now just use it as am M lens. I haven't tested it much yet but it is another impressively sharp lens. A photo of the converted mount is shown bellow.