I received one of this with a Pentax Super-Takumar 50mm f/1,4 I bought some time ago.
I warn you, this will be a very short review…
This converter, for all intents and purposes, simply sucks. This, of course, at least used with the above mentioned Pentax 50mm f/1,4 Super-Takumar.
Really, I’ve never seen anything worst. It was incapable to obtain a passably sharp image at all stops, with the possible exception of f/11 where the results were soft but at least printable.
I didn’t start with high expectations: I was hoping to use it for portraits and soft-focus shots. But it is way way too soft even for this!
Strangely enough, used for macro, coupled with extension rings, the results are almost passable. It’s just that they not justify the effort, and beside: I rarely do macro, and if and when I do I have the Makro Planar that can smoke this little old timer away.
At least I was finally able to give something the rating of “use it as paperweight”, a thing that after all this years I thought was never gonna happen!