Do Filters Degrade Image Quality?
See also other filter articles.
As I’ve begun to shoot more and more top-notch lenses, such as the Zeiss ZF/ZF.2/ZE lenses for Canon and Nikon, I’ve stopped using filters except when there is sand/dust and/or salt spray or similar hazards.
Especially with stellar “glass” like the Zeiss ZF/ZE line, and Leica APO lenses and Coastal Optics 60/4 APO, my working assumption has been that quality filters probably have no discernible effect, but then again they aren’t going to help things either.
Note that by “filters” I mean only the very best quality ones like the Schneider Optics B+W MRC line. Obviously, single-coated and/or primitive multi-coated filters are something I’m not going to entertain as an option, except in infrared, where single-coating is superior.
See my list of recommended filters.
The scene below shows increased veiling flare and degradation of image contrast with the filter. The filter wasn’t spotless, but most photographers would consider it clean enough to not have bothered cleaning it. So at the least, a less than pristine filter does degrade image quality.
The rollover below shows the results with and without the filter. Toggle to compare.
