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Are camera sensors sensitive to UV light? I thought that all modern cameras have UV protection 'built in'.

Do UV filters serve any purpose nowadays other than protecting the lens from dirt, scratches and finger prints? If so, why don't we just put clear filters on the lens?

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  • \$\begingroup\$ A clear filter would give you the same issues. Maybe a little less degradation but I haven't measured. Even expensive filters cause too much flare under some circumstances. \$\endgroup\$
    – Itai
    Commented May 21, 2014 at 16:33
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    \$\begingroup\$ @Itai I think you have provided a comment to a different question. \$\endgroup\$
    – connersz
    Commented May 21, 2014 at 20:07
  • \$\begingroup\$ I think he correctly answered the secondary question ('If so, why don't we just put clear filters on the lens?") at the end of the full body of the main question. \$\endgroup\$
    – Michael C
    Commented Apr 14, 2015 at 0:00

2 Answers 2

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TLDR; No they dont.

Long version; You are right. Modern films and digital sensors are highly insensitive to ultra violet and in most cases UV filters are just doing the protection job. This can be even problematic if the UV filter is of those cheap ones with no coating. This can result in lens flare, and low sharpness. This impact might be not easily detectable but exists nonetheless.

enter image description here

You can see the result of UV filters multiple by 19

enter image description here

source.

So, when you have a good DSLR or if you are using modern films, using a bad UV is a bad idea. It will do the protection but it will bring down your photo quality. Maybe you can afford a good lens protection with the money that you pay for a mediocre UV filter.

Personal opinion

I think there are some reasons that people keep on using UV filters but since I don't have any proof for them, I put them here.

Those who are doing photography for years, already have a handful of high quality UV filters and buying new equipments doesn't make sense.

I personally use UV on a very good digital body and very good lens. The reason I do so, I think is more mental! I am an old school photographer and I don't feel comfortable without a UV filter in front of my optics (I'm very well aware that this can raise some arguments).

Edit

As @Aj Henderson in the comments suggests, clear glass protections are not necessary cheaper. Although I agree that in general UVs are more expensive. With that in mind, I think there are couple of reasons that buyers are suggested to purchase a UV in place of clear glass protection. Firstly, many sellers are not aware of the fact that UV filters offer nothing to DSLRs. They suggest because they don't know. More cynically, I think another reason is commercial. Despite of Aj's valid point, while glass protections are fairly cheap, a good UV filter can cost up to 100$. So it would be more beneficial for sellers to sell you a UV.

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  • \$\begingroup\$ Still it doesn't explain why we don't just use a clear filter for protection. \$\endgroup\$
    – connersz
    Commented May 21, 2014 at 13:14
  • \$\begingroup\$ @connersz, actually nothing stops you from doing that. If your gears are insensitive to uv and you want to buy a protection, nothing stops you from buying plain glass protection. If something is unclear, please let me know so I will modify the answer. \$\endgroup\$
    – Pouya
    Commented May 21, 2014 at 13:20
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    \$\begingroup\$ It's not just a case of getting a clear filter, there's a lot more to it. When you buy a lens, people suggest a 'UV filter' for protection, not a clear one. When you buy a lens online, it suggests you buy a 'UV filter'. The majority of people are using a UV filter primarily for protection on equipment that is not sensitive to UV. So why are they still doing this when a clear filter is cheaper? \$\endgroup\$
    – connersz
    Commented May 21, 2014 at 13:28
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    \$\begingroup\$ @connersz - because they aren't always cheaper. For my 82mm threaded lens, a good UV filter is actually $4 cheaper than a clear. And as Pouya pointed out, a lot of us already have good UV filters sitting around, so we use what we have. If you can get a good quality clear filter cheaper, use it, but make sure it is actually comparable quality. If it is clear and uncoated, then it is going to cause problems. It needs to be good materials and good coatings or it will significantly negatively impact your optics. \$\endgroup\$
    – AJ Henderson ♦
    Commented May 21, 2014 at 13:52
  • \$\begingroup\$ I would just point out that there are some good alternatives to UV filters and clear glass, for instance, Sigma has a line of ceramic lens protection that is actually made for that purpose. For my own uses UV filters no longer have any place in my kit unless I were to get into IR/UV photography. \$\endgroup\$
    – ttbek
    Commented Feb 6, 2018 at 17:33
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UV filter as lens protection is exceptionally bad idea. The best lens protection is plastic lens cap. It is far cheaper than UV filter, and it is sold together with lens anyway. This plastic cap is designed for protecting lens and do its job well. Moreover, putting it on and off is quick and easy, in opposite to screwing UV filter into lens thread.

You take the lens cap off only when taking photo. Scratching lens, or leaving finger marks on it while taking photo is very unlikely and definitely not worth the image quality degradation caused by UV filter.

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