Optimal and offers additional protection

The image quality is slightly improved by the filter. The hazy weather is mitigated not great but at least slightly.

especially I bought the filter to protect the lens.
And since I have to say the lens is super. It is simply screwed with the thread on the tube. He really sitt resistant and so protects the lens from scratches and other contaminants.
It's a safer, more convenient and cheaper to use a filter.
The robust filter protects the sensitive glass of the lens.
you can clean the filter without the lens in hand having to hold and keep on or having to take care of the cleaning.
For severe scratches is not equal to the lens broken but the filter is easily replaced -> the filter costs much less than the retained function of the objective lens and in a broken filter. A huge advantage in shootings or on vacation.

Would be stupid, if you at the beach at the same ruined Knips box.