In buying a bunch of Takumars, a Mamiya Sekor 55mm f/1.8 (MS) came for free.
I also have an SMC Takumar 50mm f/1.4 (SMCT) and Super Takumar 55mm f/1.8 (ST),
both in good shape. The SMCT has been UV cleaned to remove a bad yellow tint.
The MS lens was frankly quite a surprise, and a good one at that.
Bokeh look a lot more like the SMCT than the ST, and frankly might be slightly better.
Sharpness wide open is not as good as the ST, but neither is the SMCT.
Flare is handled surprisingly well by the MS (better than the SMCT????).
However, the image "look" for the MS is very different from the Takumars;
in a word, it looks "Zeiss-ish" -- kind of cold, but crisp, especially at f/5.6 and up.
Given that and the lens external styling, I'm wondering if this is a Zeiss clone?
Just to be explicit about it, I am not one of those folks who thinks anything
Zeiss is great -- but they do have a "look" that is consistent across various
lenses, just as Takumars have a "look." I'm saying the MS lens seems to have
a Zeiss-ish look, and may be a cheap way to get that if it's what you want.
In short, a Tak is better, but surprisingly not in every way....
The attached shot is the MS at f/1.8 on a Sony A350; scaled, but not processed.