The Focotar 2 was recommended to me by a very opinionated person. I have an APO Rodagon with which I am pleased. I was curious as to whether it could be that much worse than the focotar.
It occurred to me that, in the same way we learn about other dynamic systems, we could not use the response to a step inout to learn a good bit about the enlarging lenses. It is quite possible for a lens to show edge effects. I am thinking of getting some thin brass shim stock, blackening it (polysulfide toner should work) and using the edge of it as a step input. My reasoning is that I have noticed that my eye shows "edge effects" in the form of fringes at sharply defined edges. This is not diffraction, because there are no color fringes, only a brighter line on the white side of the dark edge. This is in fact a well known characteristic of the human visual system. We tend to think that the edge effects we see in photographs are actually part of the object space, but I have seen them disappear when I look at the edges through a low powered high quality magnifier. Anyway, I'm thinking. At my age, that's a blessing. Mostly what I remember these days is that I used to be able to remember things.