This is a great lens that can be found at a very reasonable price. I paid $35 for a very nice copy and it offers a lot of bang for the buck. Plus it looks nice on the M10. How can you beat that. It performs like most legacy glass. Stop it down to 4 to 5.6 for the best. Wide open, it's going to be soft. I haven't done the brickwall test yet, but I'll update here when I get around to it. The images where I've used both this and the Oly 45 actually favor the Canon by a nose. This lens offers great color and sharpness, but it will probably suffer some from flare, as the coatings are of late 60's vintage. Takes a 48mm filter, and I've purchased a 48mm to 52mm step up ring to fit a hood. Processing notes: I just do basic tweaking with curves and some unsharp mask. That's all folks.