Another Rokkor 58mm f/1.2 to Minolta AF conversion

Hi,

I recently acquired an old Minolta MC -mount Rokkor 58mm f/1.2 lens (got a good price because it had stuck aperture blades, which was easy enough to repair with a bit of cleaning). Inspired by Pete Ganzel's modification of the lens, I decided to try and convert it to the Minolta AF mount.



As I don't have the opportunity to machine any new parts for the lens, I opted to substitute an M42 to Minolta AF adapter for the MC lens mount, getting the AF mount from the adapter. This required only the drilling of some holes in the adapter and sanding down a ridge on a spacer ring on the lens (with only a tiny cosmetic impact if the modification is ever reversed). From receiving the lens in the mail, planning and executing the basic modification only took about 45 minutes, so it's definitely not a hard one to do, and gives access to a very nice old lens on Minolta AF cameras, without resorting to image-degrading adapters.

The fiddly part, taking maybe two and a half hours, was readjusting infinity focus on the lens, so that the distance scale and infinity position coincide exactly on the new mount. This step requires a bit more disassembly of the lens and lots of trial and error in finding the position, but in the end the result is perfect, with spot-on infinity focus and alignment of the distance scale, as well as the lens locator dot. The project requires only an inexpensive, expendable M42 adapter as parts other than the lens.

Here's the new mount on the lens, with a link to a series of photos and a guide to making the modification in my flickr stream:



Edited by Arkku - 29 August 2007 at 16:10

Wow! and congrats! Wish I had the means to do the same... but first I gotta find that lens :))

That looks nice, would be nice to try that one som time. Maybe some day at a Finnish Dyxum meet..

Do post pictures taken with it also.

Yes, forgot to ask that! Would love to see some photos posted, especially wide open also, and f/3.5 =]

Really nice Arkku, great guide. Now I need to find one of those lens.
A 1.2 would be great for the winter here.

That sample is nice, great job adapting the lens. I used several MD/MC mount lenses on my 5D but with the adapter with glass the lens could not be used wide open, the subject would "glow" no matter what shutter speed. I have since sold them all and stuck with AF or the occasional M42 lens.

Yes you will.