The subject of whether or not to get so-called “protective” UV filters for DSLR lenses comes up a lot. I used to respond to the question frequently – so frequently that I eventually gave up and just wrote a post on the subject that I could refer people to when they ask.
However, during a recent weak moment I wrote a new response to the notion that ‘protective’ filters provide good value for all photographers. As I do from time to time, I’m sharing it here:
Someone wrote: … would you rather pay $150 on a filter that *might* compromise your shot or spend $150 on replacing the front element and have *no* possible risk of image degradation from the extra piece of glass?
I replied: This is essentially an insurance question. Obviously, if we knew that our lens would certainly be destroyed in a way that was 100% preventable by using a filter we would almost certainly get a filter. But that is an imaginary scenario that is far from reality.
Most lenses will never be damaged in any serious way. My hunch is that this is actually the fate of a very small percentage of lenses – probably far less than 10%, and I would bet closer to 1%.
Of those that are damaged, only some will suffer a blow to the front element. There are many other modes of failure – a dropped lens that breaks the mechanism, something crashing into the side of the lens, water damage, etc.
Of those that suffer a blow to the front of the lens structure, only some will result in contact with the front element. Of those in which contact with the front element occurs, some would not cause any damage or any significant damage. Some would damage the front element, but would be violent enough that the filter would not have prevented the damage. A few that might not have damaged the front element will send glass shards from the broken filter into the front element and damage it. In some subset of cases, all of the variables might line up just right and prevent damage.
At this point the user would have to replace the broken high quality filter at a cost that varies depending on a number of factors. Let’s use a figure if $100 for an expensive L zoom. The owner has now invested something on the order of $200… which is not much different from the cost of replacing a front element, as I understand it.
In terms of the probability of damage, the cost of the filter, the likelihood that the filter would save the day… the filter is probably one of the worst insurance investments you could make.
Am I unalterably and completely opposed to the use of ‘protective’ filters? Almost, but not quite. While I do not think that it makes sense to automatically stick such a filter on every lens for general use – see the link above for more on this topic – I can think of one sort of situation in which I might use one. I would consider a filter if I were shooting a sealed-body camera (such as a Canon 1-series) and was working in conditions that were truly dangerous to my equipment (and not just a bit of mist or ocean spray) and I was using of the small number of L lenses that become sealed (and not all do) with the addition of a filter.
Other than that? No.
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