Vivitar 200mm f3.5
My copy of this lens was made by Komine. This lens is capable of beautiful images if used properly.
At f3.5 it is very soft and suffers from noticeable purple fringing. It gradually tightens up until f8. At f8 it is very sharp and fringing is barely noticeable.
This is heavy and well built lens. Focus is dampened nicely. On a 35mm or full frame digital body it handles well. However, it is a bear to focus on a small mirrorless body like an Eos M.
If you can hold it steady it will give you great images at f8. F11 shows diffraction and f5.6 doesn't quite cut it if you plan to make enlargements. f4 performs as well as f5.6 if you can avoid the increased fringing. by shooting in soft light.
Contrast is excellent. Color accuracy is excellent. Bokeh is similar to most 200mm's. It is soft at F3.5 and a little distracting at f8 and up.