Vignetting at 24mm (58mm thread)

In a new price of 25 you can not expect top class, so I'll give in spite of all 3 stars.
Although the filter reduces the resolution mE not significant, that bothers me a bit of red-brown color cast, which he caused in the images. In Lightroom, I try to correct it by reducing the tint of magenta and purple saturation, which works pretty well, although I'm not satisfied 100%. When motives Photographed in which occur these colors, which could be problematic, because then you would change the picture atmosphere. That's a problem.

Furthermore, the filter is not quite as slim, white I would have expected. I got it with the Canon 24mm 2.8 IS tasted the slightly vignetting even at f8, but the filter caused here visible vignetting. I wonder why we designed slim filter that does not serve its purpose at 24mm. For larger focal lengths they are then superfluous. The vignette is not soo much, you get over it might, but then to extol as a product as Vignettierungsfrein is questionable. Perhaps the problem is the lens that used in 24mm only a 58mm thread, I can not judge.
Maybe you could be here to save the upper filter thread, even if you can slip on dan no other filters.
I still have a polarizing filter in Slim, causing no vignetting, so I put the blame on this filter.