A lot of people think they do more bad than good if you search online. Personally I am against them.Any preferences on here here for using / not using a UV filter on your lens at all times? I've always put one on for protection, so when I noticed a mark (luckily, only a splash) on my brilliant new Canon RF 100-400m glass, I bought an admittedly cheap filter.
It was awful on the long zoom - the camera is a Canon R7 with an APS-C sensor, so we're talking about a 640mm equivalent. I've attached with/without pix for comparison, will send the filter back and do without. I suspect any filter would degrade the image quality at that magnification, but I'm surprised how much.