I recently bought the nikon 50mm 1.8 af-s lens. I bought a uv filter for it. It was a "multi-coated" filter, but when I put it on, the first thing I noticed was that it causes reflections. I returned it. Now I'm wondering what is a good UV filter for this lens?
My advice is, never mount a filter unless the harm overshadows the good. Besides the digital camera sports an internal UV filter built into the protective cover glass that protects the image sensor. Yes, some filters are better than others. Generally you get what you pay for.
A UV filter prevents most ultraviolet rays from entering the camera. The UV filter was a must if you were doing aerial photography and/or imaging a distance mountain landscape etc. When shooting with film. A UV filter has the ability to cut through haze caused by the scattering of UV light in the earth’s atmosphere. The UV filter will not enhance nearby subjects. The chief reason we mount a UV filter is to guard our valued lenses from scratches and abrasions. When we mount any filter, we are adding two extra surfaces of polished glass and these add to the percentage of light lost. An uncoated filter will reflect about 5% and a coated filter will reflect about 2%. Some of this reflected light from the back surface enters the camera as wandering rays and these add flare and ghost images. Now different colors have different wavelengths and each can be mitigated by multi-coating. It is the thickness of the coat that counts. Each color needs a unique coat thickness.
If you don't have it yet, get the original lens hood. It will protect the lens and improve image quality.