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Just like the meme that you should change your oil every 3,000 miles or have your teeth cleaned every six months, the photographic retailers have their own meme going – you should buy a UV filter to protect your lens.
While I am sure many of you – maybe even most of you – have fallen for this, it’s not necessary. In this post I’ll give you my opinion as to why you don’t need such a filter and further, discuss a few pitfalls of filters in general.
Let’s work backwards. Filters in general cause several problems. They may induce flare, either the visible kind that results in small starbursts of light appearing on your image, or the more insidious kind – light refraction, which ends up reducing image contrast. These problems are caused by light leaks between the filter and lens, and the inner reflective surfaces of the filters themselves, as well as a few optical phenomena, the discussion of which would be beyond the scope of a simple blog post.
Additionally, filters can cause vignetting on wider-angle lenses. Some cheap filters apply their effects unevenly. At very small apertures, physical defects in filters can be perceived by the human eye.
There are ways to mitigate all these problems to be sure. The first and easiest way if you can afford it is to spend money for high-quality filters. The higher-quality filters exhibit far fewer of these problems than the low-quality filters. Buying filters made of optical glass can also help.
In almost every case the filters you might use are optically deficient when compared with the lenses they cover.
Now onto the UV filter as protection. All of the problems discussed above apply to these filters as well. But really, when someone buys a $1000 lens and then throws a cheap, plastic $35 UV filter over the front element – what do you expect? No need to buy the best glass if you’re just going to cover it with a cheap filter.
Here’s something you may not know. The entire reason that you’re asked about buying a UV filter at the camera store is that years and years ago, photographic marketers came up with this as a gimmick to sell more gear. The filter does little to protect your lens, but adds large profit to the retailer’s bottom line.
I don’t use a UV filter because my experience has proven I can get the same amount of protection most times from a lens hood. The idea that something will destroy my front lens element is frankly very unlikely. If I have a lens hood on – and I always do – then anything that might bang against the front of the camera that is larger than the hood will not make contact with the glass. The odds of something smaller making contact are tiny. I’ve been making photographs for longer than most of you reading this have been alive, in all sorts of situations, in all sorts of conditions and it’s never happened to me.
The good news is that the front element is usually the least expensive piece of glass in a lens so if it does ever need to be replaced, it’s not as expensive as you might think. For the 1 in 100,000 of you who experiences a problem here, I do send my condolences.
“But wait – the UV filter also helps protect my lens from dust and dirt and grime,” you say. Well I guess it does but again – in decades of experience this hasn’t been a problem for me. You have to end up cleaning the filter or the lens and most times you’d do that the same exact same way. You blow off the dust or dirt with a bulb blower, then you use a microfiber cloth to clean the remaining residue. I do this all the time directly on my lenses and nobody has ever accused me of having photos that don’t look sharp enough.
I’m not saying you should never use ANY filters on your lenses. There are two kinds of filters I use on my lenses – circular polarizers and neural density filters. I use them sparingly. I only mount them when I need them. I only buy high-end, optical glass filters. I never stack filters. These are best practices for filter use in my opinion.
The next time you see me at a convention, or a workshop or out in the field with my camera, come see for yourself. There’s no UV filter on my lens and never will be.