It would be stupid to have a lens with fine anti-reflection coating, and then put on a filter with poor multi-coating. (It's called Multi-Coating or "MC", because many years ago, it was only done with one layer, which only dampened reflections of one color, not too effective. I think all lenses today have multi-coating.)
Oh by the way, in this day and age, some makers of multi-coated filters still makes it sound in their promotion that their filter can remove reflections and flare from a lens. This is of course cattle poo. The best they can do is to not add any new ones!
I bought three different brands just for kicks and comparison. Like I expected, the old, big brands Hoya and Cokin look fine, in some light they almost are invisible.
However, Nisi, a brand I had not heard of, seems to have lousy coating. I won't be using that one. See these comparisons, the Nisi (top on both pics) and the Cokin reflecting the same light source.
(I don't know why multi-coating usually leaves green behind as the strongest reflection.)
By the way, the Cokin really is fantastically thin, the frame. Impressive. I doubt that affects the strength of the thread too much (it's shorter), unless you tend to stack filters. But it's good if you want to keep a very compact lens compact, or it's mounted on a super-wideangle where it may cause vignetting (darken the corners).
If you want one, it has the subtle and humble name of:
"Cokin 46mm Super Slim Pure Harmonie Multi Coated UV Filter"!
(Yes, Cokin is the one with the square plastic filters which you put in a holder in front of the lens. I heard that if you put them flat on tables, they collect scratches like all-git-out. I can believe it, no frame, and it's only plastic.)
|(Photo by Points In Focus)|