For those of you who don’t know what the hell I am talking about, I’ll briefly explain the issue.
When you buy an expensive lens, you want to protect it’s front glass element from scratches or other accidents. So most likely the photo dealer will suggest you to buy a UV (ultraviolet) protection filter to screw on your lens. But the question is – will shooting with UV filter degrade the image quality?
Lately I found myself bothered with this question a lot. It started when I bought my Canon 24-70mm f2.8 L lens. I bought it second hand, and the guy who I bought if from told me that it was with the UV filter all the time since the day he bought it, so it is completely scratches free. Way back I took an advanced course in optics in university, and I know that adding additional optical element to optical system changes system’s overall performance. This is exactly what you are doing to your optical system, i.e. your lens, by adding additional optical element, i.e. UV filter.
So how significant this “change in performance” is? In other words will the final image suffer in quality because of that?
I felt incompetent to perform tests to find an answer myself so I did an extensive web research, and I found a lot of information on this subject. It seems that there is no single conclusion to this matter, but here is my summary on it, which in my opinion includes all the major points, fact,s and conclusions regarding using UV filter on your lens for protection.
- Putting UV filter on your lens will certainly degrade lens’s performance.
- Explanation to this is pretty simple. When you screw on the UV filter on your lens, you basically add one more optic component, but not only that you also add a space filled with air between the filter and lens’s front optic element. So when ray of light hits your lens, instead of hitting the lens’s front element and passing to other optical elements inside the lens, it first hits the UV filter, refracts, passes to the space filled with air between the UV filter and the lens, and only then enters the lens. That ray of light can also be reflected several times between the lens and the UV filter (coating on the UV filters tries to prevent that).
- The extent of the image quality degradation may vary from invisible to the human eye to a severe degradation in contrast and sharpness (and other image qualities), and it depends on the following factors:
- The quality of the UV filter
- I found many photographers complaining about Tiffen UV filters (even about the expensive ones). I even saw a test one guy did showing that using a Tiffen UV filter significantly decreases sharpness and contrast. That guy didn’t write the exact model of that filter though.
- There is general agreement among photographers that expensive UV filters with double coating are the best choice if you must put a UV filter on your lens. Many photographers recommend the high end UV filters from B&W, Nikon, Hoya (Super HMC), Singh-Ray.
- The subject that you are shooting – or more important the direction of light. For example if you are shooting into the light, then with UV filter there are more chances to have lens flare (partial solution is to use lens hood).
- The lens. If the lens that you use is not of high quality, it may already produce less than great images, and adding a UV filter won’t make them worse than they already are.
- The quality of the UV filter
- There is everlasting debate whether one really needs the UV filter to protect the lens. Here are some pros and cons:
- UV filter gets dirty instead of the lens, so you don’t have to clean the lens that often (just clean the UV filter), thus protecting the lens’s coating.
- When shooting on the beach, or during sand storms, or in any conditions where there are tiny particles in the air, which eventually land on your lens, you are risking scratching your lens when cleaning. Better scratch the UV filter.
- Lens cleaning tip – when there are tiny particles on your lens don’t wipe them off because that can scratch the lens. Wash the front element first and then wipe it with micro fiber cloth.
- If you accidentally drop your lens, or bump it into something, the UV filter will take the blow saving the lens.
- Actually another opinion is that in such situations if UV filter breaks then its glass might easily scratch the lens.
- The degradation of image quality resulted from UV filter is negligible in most cases.
- This one is somewhat philosophic – why put a 100 dollars piece of glass on a $1500 expensive lens? It means that it is very difficult to produce a high quality lens, and this is why it is so expensive, and by putting a relatively cheap (to the lens’s price) UV filter, you must degrade it’s quality.
- Lens hood does great job protecting the lens so no UV filter is needed in most situations.
- Don’t over protect your equipment risking loosing in image quality. Be reasonable, and predict when your lens might be in danger and when not.
- The hard coating on most expensive lenses is very strong and can withstand numerous washes and cleanings (as long as you do it wisely).
- Buy Lens Warranty instead of UV filter
In conclusion, there is no simple right or wrong here. Having all the information above you must decide for yourself whether to use UV filters or not. I decided to use them when shooting on the streets or in dusty conditions, but to remove them when shooting portraits, studio, or landscapes, in other words when there is little risk to damage the lens. I also use lens hoods almost all the time. If I was a millionaire and money wasn’t an issue , I probably wouldn’t use the UV filters at all just to be sure that I am getting the maximum quality that my lens can deliver.
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Have a great day,