Filter recommendations for Fujinon GF lenses?

Painter19 wrote:

highdesertmesa wrote:

Of the protective filters I've used over the years on GF and other lenses (Canon RF, Leica M):

Breakthrough – Top quality. Never buy from their "official" Amazon store. I got two filters in a row that had been replaced – one was a fake and another was a different brand filter entirely. Always order direct from their website, and you may have to wait months for some filters types and sizes to come back into stock.

Zeiss T* UV – same quality as breakthrough but with aluminum rings instead of brass. I prefer brass, but I like the T* coating so I use them almost exclusively

B+W MRC Nano – I stopped using these as I confirmed that for some lenses they could have a negative impact on corner performance versus no filter or versus the Zeiss T* UV filter. These were genuine B+W filters from Adorama and B&H purchased over different time periods, so I ruled out it being a bad batch. I have no idea why – perhaps the nano coating can do strange things to the light ray angles with some lenses. I doubt it's because of the glass quality itself. In any case, I stopped using them completely as I didn't want to have to test every lens with them.

Leica UV – Not that any sane person would use these, but since I'm not sane, I've bought them for my Leica M lenses before. They use aluminum rings that can get easily stuck/jammed (versus Zeiss UV's aluminum rings which just tend to never get super tight). I have had these negatively impact corner performance on some Leica M lenses.

Like others, I have to use protective filters due to the environments I shoot in.

For polarization for digital cameras, I use Heliopan linear polarizers. No need to use circular polarizers and have to deal with the strange angles of darkening you can get. With a linear filter, you simply are dialing in the strength of the effect by rotating the filter.

To return to B+W for a second. Did your testing showing some loss of corner sharpness using B+W protective lenses include their clear protective lenses?

I was using only the Clear MRC Nano. Never owned (that I recall) a B+W UV.