I bought this lens a few weeks ago for very little money (about 30 euros) on Ebay. The macro is getting worn externally, but the glass has no scratches or other blemishes. It was produced from 1976 until the end of the 80s with an S.C.- remuneration (spectral coating). The lens weighs 530 grams, has a filter diameter of 55mm and a closest focusing distance of 45 centimeters. The maximum magnification is 1: 2, only with the extension tube FD 50 to reach the usual macro image scale of 1: 1.
Here are some photos with the EOS-M and the adapted lens.
Because of the weight of the lens, the combination is very top heavy. Macro shots should not make freehand but with a tripod.
Unfortunately, I could make by far my prolonged illness and the shitty weather no macro shots. But the 100mm lens can certainly be used as a short tele lens. The sharpness is fantastic, even at maximum aperture. Just as good are the colors and contrasts. This lens is just very good.
Once seen against the sun in the sky is, hopefully sometime this year - I'll try the macro function. Today there are only a couple of tele-photos.