>>3584777I've got a Pentacon 135mm f/2.8 and a Helios 44 58mm f/2.
Both lenses are M42 and fit well onto my Canon crop sensor camera as well as my Zenit-E.
The Helios is pretty good for Portrait and short telephoto at low light.
The Pentacon had some issues, it had fungus on the inside of the rearmost lens-group and the 2nd lens from the front was lose.
Even before fixing any of that it was pretty damn sharp and rivaled my Tamron 28-200mm at maximum focal length in resolving details in a distance.
After fixing that it got even better.
It's a pretty nice telephoto lens, and pretty fast as well.
Sadly I can't adapt my Minolta MD 50mm f/1.7 and Tokina AT-X 60-120mm f/2.8 to my Canon as their flange distance is even shorter than EF-mount.
But I might give it a try to modify at least the Tokina as EF is just 0,5 mm longer than MD and EF-S allows the lens to intrude into the body.
A 96-192mm 35mm equivalent F/2.8 zoom sounds pretty usefull to me.
>>3584793It isn't just important what brand the lens is, the type also matters.
Telephoto and normal lenses are usualy pretty decent, wide angle however often has issues because aspherical lenses realy make a difference in that type of lens and the where ridiculously expensive back in the day.
Anything 50mm and up is usualy at least useable.
