The UV Filter

dpreview.com is closing down their user written articles system. This is an article I wrote October 6, 2011
Beginners continually ask whether they should buy and fit a UV filter. It's like they feel their iPhone needs a rubber skin or case. Here are some points. I'll add more as discussion continues.

A few points

1. Photo gear shops make good money on UV filters and bags. It's stuff they can sell in addition to the camera. Or give away as an enticement.
2. Digital sensors are unlike film. We used UV filters (light yellow tint) and Skylight filters (light pink tint) often. While film was sensitive to UV light, digital sensors are not and hence do not need UV filters in even bright sunlight
3. Manufacturers STILL MAKE UV filters - they are not lens covers, lens protectors (I think there is one) - they are filters - that means they are not designed to be impact resistant or super strong - they are designed to filter light. If they were designed to be lens protectors, they would be designed strong.
4. UV filters add two glass/air interfaces into the optical path.
   1. Every glass/air interface means there is just one more way to cause reflections and flare. That's why the better and more expensive filters are multi-coated.
   2. Every glass/air interface means there is more risk to collect dust specks, stray hair, smudges.
   3. Every glass/air interface means there is the possibility that the glass is not perfectly flat. Unflat or rough glass reduces sharpness. How much, well that is what the debate is about and the reason why better filters cost more money.

Why some people use them

1. Some people leave the plastic wrap on their new car interior. Some people buy a sleek, sexy smart phone and immediately get a silicone rubber skin or a mock leather case. So when they buy a camera, they buy a UV filter. Naturally.
2. Some people are surrounded by little dears with greasy hands that love to touch things. Easier and less worrying to clean the filter than the camera lens.
3. Some people live or work in the desert, near salt sea spray, love to shoot in light rain. Or in dirty industrial environments spitting chips and stuff. Makes sense.
4. Some people are just clumsy. Some lenses just attract smudges.
5. Some people want to protect their investment. That's number one. Who knows, they might sell the lens pretty soon and they have kept the box and all the wrappings and they can write on their eBay ad "always fitted with a UV filter from day one"
6. They feel that if they see "flare" or unwanted reflections, yes, they'll take it off.
7. They have seen evidence or they have themselves whacked the front of their lens against a tree, the concrete floor and the filter has broken in sacrifice to the lens. Yay! Point proven.
8. They have shot thousands of shots and have never seen shots that needed throwing away just because of the UV filter.
9. Some people keep losing their lens caps in the heat of shooting and when they chuck the lens back into the bag, capless, hoodless, there is the risk of abrasion of the front element by fretting with other gear in the bag. The UV filter sacrifices itself instead of the lens front element. Easy way to burn money as the filters need replacing sooner or later. Hey, it's your money.

Why some people won't use them

1. They like "bare". Really.
2. They want purity. Putting little bits of glass in front of their lens just gives them the irrits.
3. They believe that they won't always be alert - I mean, here are you are shooting away, in the heat of the moment, will you suddenly pause and ask yourself - "I wonder whether there is a light veiling right now". These people would rather not take the risk.
4. They don't live in the desert, near the sea, live in a factory and don't have little ones - IF they venture into these environs THEN they will fit a filter.
5. They're into resolution numbers, lab tests and really, they can see / measure the degradation, no matter how slight.
6. They don't feel they are that clumsy. If they do have moments of clumsy, they would rather use a lens hood.
7. They actually fit their lens hood the right way round.
8. They've seen evidence or experienced evidence of shards of broken filters cut into the front lens element coatings.
9. Their lens isn't that expensive but has a large filter diameter. A premium priced UV filter of that diameter could cost another lens or part of a lens.
10. Their lens is pregnant and has no filter ring or won't take a filter.
11. They have seen examples where the AF worked badly and shots were degraded because someone fitted an el cheapo UV filter.

Ok, I get it but I still want to buy a filter. Which one? Is A better than B?

1. Have a look at lenstip.com - http://www.lenstip.com/113.1-article-UV_filters_test.html

Further links

Navigate to:

• Recent DP Review discussion threads on UV Filter
• Ming Thein, often intensely analytical, weighs in.

Footnote: I'm amazed how this article I wrote long ago is the top Google Search hit for UV filters.