I decided to do a quick test to see how my collection of 58mm UV filters damage image quality. I also took an image without a filter to see what difference using no filter makes. Why do I personally use filters? I want the added protection that a filter brings as well as the simplicity of cleaning a filter instead of the front element of the lens. I occasionally take the filter off when I know the situation will cause issues such as extreme reflections from that added glass. This test was intended to test reflection and glare, not image sharpness. I might eventually do another test to see if there is a reduction in sharpness.
Here is the video I put together as I was testing:
Here is an image with all filters and the no filter sample:
Results are easy to analyze. The filters without a coating were terrible, which justifies my reasoning in not using those filters anymore. The coated Promaster and Hoya filters had the best result, but still not as clean an image as the one without any filter. Seeing this result, that I basically already knew about based on my experience, still won’t change my decision about using filters. The multi-coated filters appear good enough in limiting reflection that they a good compromise. In this case I prefer to be practical rather than an elitist about image quality.