Since becoming interesting in photography, I've religiously had UV filters on the front of all lenses I use. In fact, it's become somewhat of a compulsive purchase for me - I'll buy a vintage lens from somewhere and immediately jump on amazon and order a multi-coated UV filter, making the best of my prime 2-day shipping. Some of the filters I have are no longer available as brands and products change, and I've never really seen it as worthwhile to spend close to a hundred dollars on a filter, so my experience is limited to lower budget options. In my opinion, it is worth the few dollars for scratch protection alone out in the field shooting, and a minute loss in sharpness or contrast is forgivable.
So below, I've just done a quick comparison of the various filters I have on hand. I used a Panasonic G85 on a tripod, two Yongnuo YN-300 LED lights (one directly at the camera), and the Olympus 25mm f/1.8 lens (46mm diameter). Not all of the filters I have on hand are the 46mm size, so I used step up rings to mount the larger filters to the lens - these are immediately discernible by the fading out of the reflection at the bottom left of the image. As such, when comparing a larger filter to a smaller filter here, it's best to look at the flare strength closest to the center of the image.
Please note that the dim purple flares around the light source itself may actually be related to the camera's imaging sensor itself, and not directly related to each filter's performance.
The filters compared:
- Bare lens (Olympus 25mm f/1.8 MSC)
- AGFA 46mm Multi-coated UV filter (I have probably 10 of these, ranged from 46 to 82mm)
- Altura 52mm Multi-coated UV filter
- ESDDI 58mm Multi-Resistant filter
- Fotasy 52mm Pro-1D UV filter
- Polaroid 58mm Multicoated UV filter
- Rainbow 52mm Imaging XSPro-1 UV filter (now discontinued, but this is the same company as Fotasy so I'd hope the Pro-1D is of similar optical quality)
- Vivitar 55mm Series 1 UV filter
- AGFA 55mm Multi-coated UV filter (AGFA also falls under the Zeikos brand)
I've just gotten a Hoya HMC filter, but its 43mm so not present on this test (for now). So, on to the comparisons. Diagnosis text is just below each image.
↑ AGFA 46mm. Here the reflection is noticeably defined, with a green tint, at the bottom left. Brightness around the light source is natural looking, with some dim purple ghosting around each of the four reflectors on the light.
↑ AGFA 55mm. Similar qualities to the smaller size, but a little more definitely to each individual LED in the reflection. Reflection has faded out away from center. This is just to illustrate the differences between the same filters but in different sizes. We can extrapolate this information to visualize the other filters if chosen in different sizes.
↑ Altura 52mm. You'll notice that this filter's reflection is noticeably brighter than the AGFA filters, and the purple ghosting near the light source is stronger (especially visible if looking at the prism of the Olympus OM-1 body just below the light).
↑ ESDDI 58mm. This filter appears to perform on a similar level to the AGFA filters, but with slightly more purple ghosting near the light source. I really love the construction of this filter, the rim is glossy metal instead of matte, and has nice ribbed grips spaced out in four groups around the diameter. It is also one of the easiest to screw on smoothly and securely without getting stuck, so this particular one usually lives beneath a variable ND filter for video, and the variable ND is easily unscrewed when taking stills.
↑ Fotasy 52mm. This one definitely has a different tint to the reflection at the left, still green but with more white mixed in compared to the AGFA or ESDDI. It doesn't actually seem to be much brighter of a reflection, but it seems more noticeable because of the color.
↑ Polaroid 58mm. This filter is described as multi-coated, and even has a "MC" etched into the side of the filter ring. However, I don't see any evidence of coated glass and the reflection is a strong white color.
↑ Rainbow 52mm. This surprised me - this filter seems to be discontinued (I have a few, one as large as 82mm) and replaced by the Fotasy Pro-1D. However, this older model is definitely better than the new Fotasy. In fact, I would probably call this the best performer in this set, with the AGFA very close behind. It has the dimmest reflection, the most natural color tint, and doesn't exacerbate the purple flaring issue near the light source.
↑ Vivitar 55mm. I purchased this on Adorama to go along with an Olympus 35-70mm f/3.6 and immediately regretted not doing more research. It's definitely not a multi-coated filter, and has a strong white glare. It serves its purpose as a protection filter but that's it. Comparing it to the Polaroid filter, I wouldn't be surprised to discover that these are made in the same place to the same specifications.
↑ No filter. Hashtag no filter. The lens itself handles flare exceptionally well, with the reflection basically eliminated to a patch of slightly green haziness. The purple ghosting around the light source remains present - so this is definitely related to the lens or sensor and not an effect of mounting a filter.
So overall, I think the AGFA provides great bang for buck in this segment, but the Rainbow is probably the best performer if you can still find one. For utility, the ESDDI is nearly as good as the others but has the nicest physical construction. The only negative to the ESDDI is that I can only find it in three sizes, 58mm, 67mm, and 77mm. I'd love to add Zeikos, Tiffen, and Hoya to this test in the future, but this comparison was really designed to focus on the ~$10 filter segment. I'd expect an uncoated Tiffen or Hoya to perform worse than any of these, and the coated filters from those companies generally come in at double to triple the price of the others in this test.