[Update Feb 21, 2009]
After some observations, I must say that this lens is possibly made by Tomioka. The glass and coating looks the same as my other Tomioka lenses. The only difference is the rear element, which looks bigger than the others, but it's only because the others's edges were rounded, whereas the Petri is flat and makes it look like larger.
[end update Feb 21, 2009]

[update on the err 01]
It turns out that one of the three bayonet mounting clamps engages the lens detection switch on my 1Ds when fully mounted. Most EOS camera don't have this switch, except the 1-series. I filed the clamp shorter so that it won't push the switch to the on position. Problem solved.
[end update]

This lens has been sitting in the junk bin at home for years, and before this, at the dealer's junk bin for years! It's a Petri mount. How many Petri cameras have you seen in your life time, although Petri did sell some M42 lenses/bodies. I could not find an adapter to use it, and couldn't get rid of it after 3 yard sales at $10 :-) But, this is one nice looking lens with the rear element that is unusually large, compared to other 50/55mm f1.4 lenses.

I have finally decided to give it a transplant by removing it's original mount, and glue a Canon EF mount that I removed from a defective lens. It's difficult to get it to work, because every time I mounted the lens, I got an error 01 when a picture is taken. I had to mount this lens until it almost clicks and then it works fine. The signal pins on the camera must be in contact with the lens mount somewhere. But I have been able to take some pictures with it. Not the sharpest lens in the world wide open, but on par with other Japanese 55mm f1.4 lenses that I have. Bokeh is actually quite nice, despite the aperture blades are not symmetrical when stopped down to f4 or smaller.