I bought a couple of inexpensive Rokkor 50 mm's to experiment. This Rokkor 50 mm f1.4 doesn't have the 8 screw mount so it presented a challenge to fit the M42 to EOS adapter. The lens fell out of my hand onto the bottom of the work bench. It proceeded to drop to the floor while I was moving the boxes around to retrieve the lens. The front rim got dented but nothing else seemed to be damaged. So that gave me the bold move to butcher the lens mount.
I chucked it on a lathe and start cutting away the Minolta mount. Then I cut the inside of the M42 adapter to match the steps on the existing mount. By the time I finished I drilled and tap some 2 mm holes on the side of the adapter and tightened them against the lens.
I did cut away .5 mm to get the lens to focus to infinity.
I have not touch the retainer ring on the rear element and my 5D mirror is not hitting.
Here is a picture of the lens by itself and a picture of it mounted on the Canon 5D.
The chromed bronze adapters seem to be more robust.
I typically tap all the way through the minolta mount stalk and turn the setscrew thought the stalk wall, then loctite the setscrew, versus screw into the stalk wall with pressure.
Thread out the lens ID ring if you can due to it being bent, unscrew the filter cylinder, and maybe you can straighten it with a mallet or something, while you infinity adjust the lens.
>>The chromed bronze adapters seem to be more robust.<<
The chrome bronze color you see is really the existing Minolta mount. The M42 to EOS adapter is only aluminum. Very soft and pretty fragile.
>>I typically tap all the way through the minolta mount stalk and turn the setscrew thought the stalk wall, then loctite the setscrew, versus screw into the stalk wall with pressure.<<
I may eventually do that if the mount come loose from use.
>>Thread out the lens ID ring if you can due to it being bent, unscrew the filter cylinder, and maybe you can straighten it with a mallet or something, while you infinity adjust the lens.<<
I didn't think about that. What do I use to unscrew the filter cylinder? The rubber clamp spanner?
Right now I am right pass infinity and I have not taken the lens apart yet. I have to rest my heart a little before proceeding.;-)
I have one of Jim's converted Rokkor 50 f/1.4s....truly a great lens, and for my money, I like it better than the 58/1.2. Of course, I lose an extra half stop, but I find the 50/1.4 a lot easier to focus wide open, and consequently I get a lot more keepers.
I got a question. I found out I am not getting infinity focus. Should I cut back the mount and adapter some more and do I need to do an infinity focus adjustment?
HansenTsang wrote:
I got a question. I found out I am not getting infinity focus. Should I cut back the mount and adapter some more and do I need to do an infinity focus adjustment?
If your happy with the fit and robustness of the mount, then adjust infinity with the lens adjustment screws.
Get a spanner wrench, unscrew CCW the lens ID ring. Underneath are 3 screws that secure the focus ring. If you are not quite getting infinity, at infinity position, loosen the three screws to where the focus ring moves freely and turn it back 2 or 3 mm, then tighten 1 or 2 of the screws to secure. Now the focus ring will turn a little more toward real infinity. Once you've got real infinity, loosen the 3 screws again, turn the focus ring to infinity setting and tighten the screws, thread back on the ID ring and your done.
