I first bought the K&F Nano series filter for one of my lenses. I believe it was for my Nikon 80-200mm F2.8 D ED lens. This lens produces really sharp images at a distance and is not a close focus lens, even noted by Nikon. I bought the lens used and it came with a dented UV filter. I got ghosting and when I removed the filter the ghosting was significantly reduced. I ended up buying several more for my other lenses. I also use B+W filters. Well-made filters too, but a little more expensive. The K&F is by no means a $100 filter, but for the price it does what I need it to do. I particularly like the grease and water-repellent nano-coating. Worked well when I was shooting at the beach. The sea fog is easy to remove,
We really don't need UV filters anymore with digital because UV doesn't interfere with the sensor like it did with film. I just use them to avoid having to constantly clean the front elements of my lenses. I think keeping this to a minimum will prevent potentially scratching the element. I know there are a few schools of thought on this subject, but I just do what I'm comfortable with. From what I've read and can tell, the filter is glass and not plastic, which is nice these days. I have them on all my lenses now and am happy with them.