The subject of using or not using protective lenses can invoke heated debates among photographers, with both sides often fiercely defending their choices. I am not going to debate whether it is right or wrong to use protective filters – that’s certainly a personal choice. I have been using them for a number of years now to protect my higher-end lenses and make it easier to clean lenses with recessed front elements (such as on Nikon 50mm f/1.4G / f/1.8G). Having had bad experience with purchasing a low-quality no-name brand filter when I just started photography (it was sold to me as a “must-have” at a local photo store), I learned what such a filter can do to my photos the hard way. Since then, I have only been purchasing multi-coated B+W filters that use high-quality Schott glass. I have been very happy with these filters and have been telling our readers to either use the best they can find, or not use filters at all.
A couple of weeks ago, I received a bunch of filters from a new filter manufacturer in Europe. The company wanted me to test their filters and see what I think of them. I asked them if they would be comfortable with me comparing their filters to B+W and they told me that they did not mind. As I was testing a lens in my Imatest lab a couple of days ago, I first shot a test chart without filters at f/5.6, then stacked 4 of my 77mm B+W XS-Pro MRC filters and took another shot, then finally mounted 4 filters from the new manufacturer and took the last shot. Here are the numbers that were produced by Imatest:
As you can see, the B+W filters had no impact on image quality. The differences in numbers between “No Filter” and “B+W” you see above are within the margin of error. However, if you look at the third graph, it is pretty clear that the filters that I was testing were of low quality. There is a rather significant drop of approximately 5% in the center frame, a drop of 7% in the mid-frame and a pretty significant drop of close to 15% in the corners. To make sure that I was not making any errors, I re-ran the test several times and used completely different sets of filters from the same manufacturer (I had a total of about 20 77mm filters that manufacturer regarded as “high quality”). Other batches yielded similar reduced numbers, some worse than others.
I wanted to see what a 15% difference in score represents visually, so I took extreme corner image crops from an image that was shot with 4x B+W filters and the same with 4x lower quality filters. Here is what the comparison looks like:
As you can see, the difference in sharpness is pretty clear – lower quality filters certainly result in visible image degradation. Details are blurred and the straight lines are no longer sharp. And this is just sharpness alone. If I shot with the two in a high contrast situation (say shooting against the sun), I bet the low-quality filters would introduce all kinds of artifacts to my photos.
Yes, this is a rather extreme example and I know that nobody would stack 4 filters like I did above. If one were to look at images with a single filter, the differences would be very minimal. However, that’s not what I am trying to show here. The point of the article is to show that high quality filters have no effect on sharpness and do not necessarily reduce image quality, as some photographers claim. It is certainly the case with lower quality filters though. The only thing that filters might introduce to images, is more flare and ghosting when shooting against a bright light source. In those situations, it might be best to remove filters altogether.
Lastly, keep in mind that the filters I tested were regarded as “pro” filters. If you are curious to know what a single cheap / bad quality filter can do to an image, see this article that I posted last year.
Moral of the above research: not all lens filters are made the same, even from the same “high-quality / pro” category…
Thank you for the information. I once bought a Hoya but switched to B+W and I am presently looking for a filter for my new 18-200mm Tamron and I wasn’t sure if I should stick to the same brand. Reading this, I will.
Thank you Nasim. Very handy article as I am considering which filter to get for a z 70-200mm (I use filters as mechanical fuses – glad I broke 2 of them instead of the front element on my lenses.)
A lot better test would be between B+W filters and Hoya filters which most people I know use. Too many products demand a premium price due to the brand name not increased quality .
I wanted to buy b+w filters after reading your post, but I was looking for square ones, and b+w don’t seem to do any. Do you know of any good quality brands that do square filters?
From the other side of the coin.
This test (clearly?) shows that you need stack FOUR layers of low grade filter in order to be able to demonstrate its weakness.
Hot sure if this thread is still being followed.
I did a search on B&H for a 5 stop ND filter in a 77 mm size. There were 11 options that came up, ranging in price from $63 to $282 for a Heliopan, a brand I’ve never heard of. B+W was NOT an option for this filter in this size.
I’m not one that believes that quality and price go up and down in direct correlation to each other. But I also know that good quality does not come cheap. Nasim, have you looked beyond they B+W brand? What is the gain, if any, by spending the BIG bucks? Do I stick with Tiffen and Hoya, brands that I’ve been familiar with for decades, or do I look at high priced brands that I don’t know, like; Schneider, Singh-Ray or Heliopan?
To be clear, I’m too stinking cheap to pay more than I need to, and too stinking fussy to settle for anything that will detract from the quality of the final product.
Who has good experience to share with me?
The Hoya are surprisingly good and I normally have a Hoya multi coated UV filter on most of my lens. In a few instances I was able to find a B+W at a discount price so I have a few of those as well. There are a couple of web sites that have done tests on filters, Hoya was often at the top or near the top of the list.
Nasim, Thank you for careful work the detailed explanation of your findings. I’m going to think hard about the savings vs quality (that is, in general, no-brainer)
I was going to comment, but, noticed that I replied in April, 2014 :-)
My thoughts on the subject have not changed as well.
how about marumi filter? Anyone tried it?
I have a few of the higher end Marumi filters. They are very good. I use Marumi and B+W filters.
Filters are always an interesting topic, I have seen a few web sites with lengthy discussions on this topic and your experiment was conducted several years ago, it was by a fellow who works at a camera shop if I remember correctly. Still an interesting topic, and a good experiment to stack the filters like that. Personally I do stick a clear or UV type filter on all my lens just to protect the front lens glass and if I get mud or sea spray on the filter its far cheaper to replace the filter. I have tried B+W, yes, good glass. I’m not a professional photographer, never make a print bigger than 8X10 and typically I am taking pictures of my grandkids and some scenery on trips. I suppose there are a few others who could identify with my photographic style. So having said all of that I have some B+W filters but mostly I use the Hoya multicoated filters. I have Nikon DSLRs and some Olympus Pens. Recently bought a B+W filter for the Olympus, a 37 mm UV. Interestingly the thread on the B+W was cross threaded to all of the Olympus MFT lens that take the 37 mm. I eventually tossed it out. On the Hoya multicoated fiters, also in 37 mm, I got some grime on the filter so got out some lens cleaning spray and lint free cloth, it appeared to take the multicoating right off the filter. Had permanent streaks after that. I had used that cleaning method many times before, so I guess some filters are just not consistent in quality. Anyhow, I found your post interesting.