Bought a Micromega Critical Focuser with blue filter. Did first printing and so far very happy. The only concern is to how the blue filter works. My focuser has integrated switch-blade-filter. From what I found it is recommended to use filter for a better tuning to get sharpest grain. I've read the book by Gene Nocon where he says about Omega focuser being exceptionally good but there is no specification on how to get it work. I don't really see the grain through the blue filter but rather different light tone which in my case doesn't make any difference. Grain comes from using the focuser without a filter. I will really appreciate any given information.