Vivitar 70-210mm f2.8-4
My copy is a Komine: the third version w/ the red line inside the filter ring. It is considered to be the best version Vivitar offered. My copy has a PK mount. The adapter for my Eos M3 had a slight play in it but no wobble.
First, I'll tell you what you already know. It's a great lens. Like all Komine lenses it is built very well. Focus is silky smooth and perfectly dampened. One touch zoom is smooth and holds position well. Aperture ring clicks nicely into both full and half stop settings.
IQ is excellent. Color is very accurate. Contrast is excellent thru most of the range except for backlit shots.
At f2.8 it is genuinely sharp. At f4 it tightens up to tack sharp. It does exhibit bokeh fringing and bright edge fringing at f2.8. Fringing is greatly reduced from f4 and up.
Macro with this lens is 1:2.5 and it engages very smoothly and automatically. Close focus is a close 2.75 feet. Macro is available from 100mm to 210mm.
Bokeh is smooth at all apertures. Yep, that's what I said. Komine put some thought into this lens.
You will not need sharpening when processing images from this lens. I wonder why Vivitar bothered marketing a prime 200mm. I'd rather have this tele-zoom.
Despite this lens being heavy it is manageable and handheld images on the Eos M3 were not much trouble, but if you have small hands it will be a chore.