Just like the old “film vs digital” or the “Nikon vs Canon” debates, lens filters often create endless discussions on the Internet. Some people argue that one should never use protective filters, since it is another piece of glass in front of the lens that reduces resolution and emphasizes other optical problems such as ghosting / flare, while others argue that filters make it easier to protect the front element of the lens and make it easier to clean that element. I personally have been recommending use of protective filters for years, as long as they are of high quality. The filters that I have been using do not seem to affect the resolving power of lenses they are mounted on and mostly do not seem to heavily affect ghosting / flare either. Having spent the last couple of weeks in a lab testing many lenses, I wondered if I could actually measure the resolution of a lens with and without a filter. I recently purchased a used lens that came with a crappy plastic filter, so I decided to run two separate scenarios – one without a filter, one with a high quality B+W filter (more on B+W products below) and one with a cheap plastic filter. The results of the study came out very interesting!
Armed with the Imatest software, I first measured the sharpness of the Nikon 70-200mm f/2.8G VR II lens, which is usually my reference lens for telephoto sharpness. The focal length was roughly 150mm and the aperture was set to f/5.6, which is the sweet spot of the lens. I then mounted a high-quality 77mm filter by B+W and did it again. Here is the result of Imatest measurements:
If you look at the above charts, they look pretty much identical. There is a slight variance in numbers, but that’s expected when going from one image to another – Imatest scores can be slightly different even when you do not change anything. Judging from the above case, using a high quality filter does not affect the resolving power of the lens at all. This is a good scientific proof for those that claim that all protective filters decrease resolution. Myth debunked!
Let’s now move to a second case scenario. What if you were to use a cheap, low-quality filter? As I have mentioned above, I recently purchased a used lens – the Nikon 55mm f/2.8 AIS that came with a cheap plastic filter (more on this project on a separate post). So it was a perfect case scenario to see what the resolution would look like with and without the cheap filter. Let’s take a look at what Imatest measured (shot wide open at f/2.8):
Now this is an interesting result. Looks like using a cheap filter does indeed affect lens resolution. There is about a 10% drop in resolving power across the frame! And I am sure, if I were to take this lens and shoot it against the sun, this particular filter would surely make ghosts and flares appear worse.
This was an interesting study, because it proved that high quality filters have no affect at all on lens resolution. If you keep them clean and in good shape, they also do not affect the ghosting and flare properties of the lens. You might see a little more ghosting/flare on some filters, but if it annoys you, simply dismount the filter and put it back on once you are done shooting against the sun. It is not like you would shoot against bright light every day right? From my experience, the multi-coated B+W filters have no affect on ghosting/flare, so I never bother to dismount filters when shooting against the sun.
At the same time, make sure that you are not using cheap, low-quality filters. As you can see from this article, cheap filters do indeed affect the resolution of the lens and they can seriously affect the ghosting and flare properties of the lens. I have seen reduced contrast and really nasty ghosting / flare with cheap filters before, so I have learned my lesson on not buying those.
If you are looking for recommendations on what filters to use, I have been a huge fan of B+W filters. All filters that I buy (neutral density, polarizing, clear) are B+W brand. They are made of high quality glass and they are manufactured in Germany – so you can expect the best performance from them. A key feature you should always look for in high quality filters is MRC, which stands for “Multi-resistant coating”. No matter what brand you go with, always make sure that the filter comes with this particular coating. This anti-reflection coating is the key to getting little or no additional ghosting/flare in your photos.
The one I usually get for pro-grade lenses is the B+W 77mm UV Haze MRC 010M Filter. At $72, it is not a cheap filter, but it is worth it as you can see from the above test results. I have been using this particular filter for several years now. The last thing you want to do is mount a $10 filter on a lens worth hundreds, if not thousands of dollars! There is a new XS-Pro version of the above filter, which is slightly more expensive at $87 (adds nano coating), but I doubt that it will make a huge difference. I have purchased a couple of those recently and I cannot say that they are better in any way. Note that UV protection is not needed on digital cameras, because sensors have a built-in UV filter. So when you mount a UV filter on a modern DSLR, it simply acts as a clear filter. So either buy a UV or a clear filter – both should be as good.
Obviously, you have to choose the right filter size for each lens you own. The above links are for lenses with 77mm threads, so if you need another size, simply type something like “B+W 67mm MRC” in the search box at B&H and you will find a clear filter quickly. You will see that as the size of the filter get smaller, the price of the filter is reduced as well. For example, a 67mm B+W MRC filter costs around $43, which is significantly cheaper than the 77mm filter.
If you do not know much about filters, I wrote a detailed article on using lens filters. Give it a read – it is pretty extensive and covers all of the above-mentioned filters.
For full-on geek, scientific testing of protective filters: www.lensrentals.com/blog/…he-market/
Published June 3, 2017
Any thoughts about lens filters for the iPhone 14 pro? I want to protect the lenses but not affect photo quality.
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Thank you for this interesting comparison, Nasim. I’ve used B+W filters for both colour and mono films for at least 45 years. First on Nikon F/F2 and now on Leica R6. They are top quality and despite using some of them for well in excess of 30 years, they show no wear. The B+W filters are certainly the equal of Nikon and Leica but have a heavier mount. I like this and find them easier to handle. All my 55mm Filter mount Leica R lenses have UV/IR filters on and I have coloured ones for mono work and polariser for colour. I don’t use digital. If a camera needs a manual with instructions, I don’t need that camera.
Could you take a company taht has a full line from disgusting to excellent, and do a test on a good lens with each?
In this case you used a cheap plastic filter on a meh lens, and got about a 10% degradation.
That makes me think that the the difference between the top of the line and the #2 or #3 in a lineup will be minimal.
Do we need to remove the UV filter when using the graduated ND filters adaptor ring , to avoid any image dégradations ?
think your review is quite inaccurate and misleading. I find the B+W filters to
be incompatible with the new micro-crystal lens coatings and there is not one
shred of laboratory test evidence that these filters perform any better than
filters of one half the price. I personally notice that with my 36 MP sensor
that the B+W filters seem to produce a slightly less sharp image with increased
ghosting and flair. Furthermore you regurgitate the “Schott Glass” sales pitch
blindly without researching the fact that “Schott Glass” is not a
thing, it is not a special type of glass but rather simply the brand name of
Schott Glass Company, a manufacturer of window glass and stemware. One more
problem I have seen repeatedly is their failure to stand by their product. Why
do they refuse to do that if their product is supposedly so good? I returned an
obviously defective 77e circular polarizer because the outer ring did not
rotate and they flat out refused to make right and replace the filter. They
said they don’t make that filter any longer so they would not honor the
warranty that it came with. They say other filters are “made from window
glass” but in fact their filters are the only filters truly made from
window glass aside from the $5 variety no brand filters from Walmart.
Nice information. I am purchasing a B+W ND 3.0 filter. It comes in MRC ($140) and non MRC ($95). Because i already own a B+W UV MRC, i am wondering if getting the non-MRC version ND makes sense because it is to be screwed onto the UV MRC filter. Thoughts? Thanks
I ordered a B+W 77mm UV Slim MRC 010 filter from an online vendor. When it arrived, I found the box was sealed only on the top side – the bottom side had no seal at all. Is it normal?
I am trying to decide on a filter for my new Ultra Wide zoom = Canon EP-S 10-22mm. B&H recommends that I consider a slim filter to avoid vignetting issues. The 2 filters I am trying to decide between are the B+W 77mm UV Haze SLIM MRC 010M or the 77MM XS-PRO UV MRC-NANO (010M). I get the impression that the nano lens is also slim, but not sure whether slim enough to avoid vignetting on UWA lens. I like the idea of easy cleaning of the nano lens, and it appears it does have some threading so that the original lens cap could be used. The nano filter is also cheaper than the Slim MRC. Not sure whether either filter would allow me to use in conjunction with a lens hood. Your thoughts?