UV or not UV
UV or not UV; that is the question…
I’ve been putting off posting this for some time now as if I am not careful, I am going to open myself up for a massive debate, or perhaps argument, around UV filters; and quite frankly, “ain’t nobody got time for ‘dat”.
If you are coming here for a definitive answer once and for all, I am afraid you are going to be a tad disappointed. Instead, I am going to put on my ‘impartial hat’ and try to give as much information for each side and let you make up your own mind. From time to time, I may accidentally slip into ‘personal preference’ mode and bias one fact over another.
So, the question is; do I really need to fit a UV filter to my lens? Well, in all honesty the answer is both yes and no. You see… impartial hat!
Let us start off by going way back in time, to an age where photographers used to put strange rolls of things called ‘film’ into their camera. For those of you under the age of 25 and unfamiliar with such a concept; it was a bit like a very small capacity memory card, which could hold just 24 photos (or 36 if you were posh). The image was exposed onto a piece of light sensitive material like some kind of witchcraft! With colour film, the light is split into its Red, Green and Blue layers. This works well in theory, but the blue layer was very susceptible to UV light. On a bright and clear sunny day where UV light is high, you tended to get a blue-ish haze to your images. Cue the development of the UV filter. As is pretty evident by its name, a UV filter cuts down on the amount of UV light hitting the film, reducing the nasty blue haze on your photos. Wonderful!
Step forward however, and the need for the filter starts to come into question. Digital sensors are not generally that sensitive to UV light, and no not demonstrate the same issues as early colour film. There are some people out there who will stand by their UV filters, adamant that they reduce fringing or chromatic aberrations, but generally speaking, a UV filter on a modern DSLR will do diddly squat.
So, if a UV filter does nothing these days, why do people still buy them by the truck load? The purpose for these filters has some what changed over the years. People no longer buy them to protect their images from UV light; instead they buy them to protect their lenses from everything else. Much in the same way as screen protectors on our smartphones, UV filters protect the front element from getting damaged. Dust, dirt and finger prints are easy to clean from the filter and if it gets scratched, it is a lot easier and cheaper to replace a filter than it is to replace the lens!
All of that sounds excellent, and gives a pretty good justification for continuing to buy UV filters. However, as with all fences, there is another side to sit on!
While the concept that UV filters protect the lens is absolutely true, there are some people out there who believe that by fitting a UV filter, they have enabled some kind of ‘Indestructible mode’ and that treating their lens like crap will not damage it. Unfortunately, those people are wrong! Realistically, any hit or drop hard enough to smash a UV filter is likely to have damaged the lens as well, and a lens hood will do a pretty good job of shielding the front element from most airborne detritus.
“Ahh, but they do protect from scratches?” I hear you cry. Yes, you are indeed right; that filter you have just thrown away is probably covered in scratches. Would any of those scratches actually have occurred on the toughened glass element though? The answer is more than likely, no. You see, the filter is made of much lower quality glass, or perhaps even plastic. This softer material is going to incur scratches way easier than the front glass element, giving the illusion that it is working effectively.
Image quality is a big deal, and the reason why some of us spend thousands upon thousands of pounds on the best quality glass we can. Everything is made to such a high standard, and offers such amazing image quality; why on earth would we then stuff 20 quids worth of crappy, low quality glass right in front of all of that hard work? This is where the debates and arguments come in with people fighting from both sides. There are obviously different brands at different prices, offering different levels of quality, ranging from a few pence to a few hundred pounds. Are there any discernible differences between them? Well, that is really up to you and your eye. I will say though, not all glass is created equal! Cheaper materials, cheaper manufacturing processes and less stringent quality control all have an impact in the quality of the finished article. A filter ‘should’ be optically flat, not altering the direction of the light in any way. Any slight imperfection will cause an issue to the quality of the image. Can you say for certain that your filter meets those criteria? Has your £20 filter gone through the same quality control as your £2000 lens?
Another argument is that glass does not let 100% of the light through it, so by adding more glass to the front of the lens, you are cutting down on the light entering the camera. Now, this can vary from a negligible amount to a significant amount, again depending on the quality of the filter. It is not something I have ever really experienced but it is worth considering.
Something I have experienced and is worth considering is lens flare and ghosting. Now on its own, lens flare is a big issue and should be addressed, but quality lenses have special coatings to reduce or stop lens flare occurring. A lot of the filters out there do not have this coating, and as such flare at even the faintest hint of sunlight. Conversely, in dark scenes, strange reflections and ghosting can also be seen, where light is reflected around and bounced off the back of the filter. The more money you spend, the better the coating but it can still be an issue.
So should you run a UV filter or not? Yes, if you want to protect the glass and no if you want better image quality with less lens flare. Personally, I do not use them. I would rather make full use of the glass I have paid for and not chuck lower quality glass in front. I keep my lenses clean and use hoods the majority of the time.
As I said before, I am not going to definitively answer the question as frankly, there is no 100% answer one way or the other. It is down to you, your personal preferences and the situation you are in at the time. If you are shooting in a particularly dusty environment or something, perhaps chuck one on while you are there.