Just got my 50 mm f1.2 instead of the 58 mm f1.2. The conversion was a bit easier than I expected. This one has a 4 bolt mount without spacer.

As soon as I finished I ran outside and did a few shots to test. This was done with my 1DsMk3.

The first one is a Lehua bud at f1.2. The second is a 100% crop.

This next one is when I closed the aperture to f2.8.

At 100% crop you can see how sharp the lens is by the hairs on the Lehua bud.

I didn't do anything to the focus adjustment. I did shave a bit off the M42 to EOS adapter so the flange is just below the rear element at infinity. I got infinity without problem and there is no mirror issue. As a matter of fact I can focus beyond infinity right now.

The infinity shot is at f1.2 also.

The 100% crop shows the power lines that I focused on.

Not bad, looks a lot like my Pentax 50/1.2. How're the out of focus highlights at large apertures? my pentax gives rings to gaps in leaves etc, but is ok with totally point light sources.

Here is one with the Christmas tree lights in the background at wide open.

Here are some pictures of the lens itself.

First one is on the 1DsMk3.

Second one shows the adapter.

Third one shows the rear element sticking out pass the adapter.

All these were taken before I touch up the lens with black paint.

Slide the aperture ring back against the adapter to prevent light leakage. To fine tune infinite focus just remove the rubber focus grip then pull the tape loose. With the tape off mount the lens and set infinite focus then re-tape and put the grip band back on.

tm

Thanks, I took the original adapter and cut off a thin ring of material to use as spacer between the aperture ring and the mounting flange. It is hard to see because it is black.