if filters, then please a B + W

I was for a long time on doubting whether I should really screws on my faithful and not-effective Canon 24-70mm 2.8 L a possible image quality-reducing filter.
That it is not the cheapest was clear and because of my previous positive experience it was the B + W filter of German manufacture.
I had yet to determine any occasion negative influences of the filter and I have it now but already some shootings on it. In windy weather on the sandy beach I feel with the filter, however, significantly more comfortable.
From me strong buy recommendation.