The filter is very good. I have tested it with Canon 5D mk2 + Canon 24-105 f / 4 IS. Aperture f / 9.5. Just as sharp as without, no color shift, nothing wobbles, the sky is dark blue, normal color saturation ... What else you need? Two sample photos: with the filter (max dark blue) without filter
I am very pleasantly surprised. One can get a good product for 21 euros instead of more than 72 euros. Highly Recommended.
