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Good Times with Bad Filters

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OK. First and foremost this is a fun post. It is not episode 362 of “Should you put a UV filter on your lens”. Some people use them. Some don’t. There’s not enough bandwidth to ever end that argument.

But here at Lensrentals, we have a ton of filters. We have some really good, very expensive filters. We have some OK, middle of the road filters. And because some customers, uhm, happen to return a very cheap filter in place of the one they were sent, we’ve obtained some crappy filters. Brand names aren’t necessary. If it cost $22 in 77mm size, it’s a crappy filter.

Anyway, one of the techs has to clean all those filters, make sure the threads are OK, and test them out. Honestly nobody likes to do it, so it gets put off until we need some filters or there’s just nothing else to do. So the other day Kenny is cleaning filters and testing the threads by mounting them one in front of the other until he made a nice mountain of 50 UV filters.

50 UV filters, cleaned and neatly stacked.

Not being the kind of people to let well enough alone, we decided to mount them to a 5D Mk II and 300 f4 we had handy and take a few pictures.

The well protected lens.

And of course see if the filters affected image quality. See if you can tell which images was shot with the 50 UV filters, and which without:

Shot of the building across the parking lot without filters (above) and with 50 UV filters (below). The one with the filters is actually better than I expected.

Of course there’s a lot of vignetting and haloing on the full size image:

Compared to no filters

Roger, do you have anything constructive to say, or are you just wasting blog space again?

Yes, actually I do. Fifty filters stacked is pretty ridiculous. But in that stack of 50 filters, as I said, there are some very good ones and some very bad ones. Lets compare a stack of each, shall we?

First, I had Kenny put the worst filters on the top of the stack (all were nonbrand, or brands we know are cheap and bad) and take a picture of the stack at an angle. All were freshly cleaned and if you look straight through them reasonably clear. Like a filter should be. But if you stack them and try to take an angled picture through several layers of them, the results were ugly.

View through a half dozen cheap filters stacked on top of each other. Try counting the filter rings inside the stack.

Yes, I know they don’t look clean in the image, but every one of those filters was freshly cleaned, and checked under a light. And if you look straight through them they were pretty clear. Looking at an angle tends to show you the weaknesses of a filter much better than looking straight through it. And remember: most of the light rays coming into the lens are coming in at an angle, not heading directly to the sensor in a straight line.

Now lets compare the stack with the expensive, top of the line filters (B&W, Heliopan, etc.) stacked the same way.

Stack of expensive UV filters one atop the other.

Hmmm. I’m starting to think there might be a difference here. But the proof is in the pudding. Lets modify our original experiment to something only slightly ridiculous. Instead of shooting through 50 filters, lets take the shot through 5 top of the line filters and another through 5 bottom of the line filters.

Here’s a 100% crop of a bumper sticker across the parking lot shot first with no filter, second with 5 stacked high end UV filters, and then with 5 stacked low grade UV filters.

100% crops of a bumper sticker shot through no filters, 5 stacked good UV filters, and 5 stacked cheap UV filters.

Now stacking 5 filters doesn’t have a ton of real world implications. Most people rarely stack two. But it is a fun demonstration that there really is a difference between good filters and cheap filters.

The good filters do a remarkable job: 5 stacked filters means 10 air-glass interfaces before the light even gets to the lens. That there’s only a little bit of image quality loss through all those filters is pretty impressive. This crop is from the center of the image, there’s more degradation to the sides, but still, it’s an impressive performance. And certainly lends credit to the idea that a high quality, multicoated UV filter has little effect on image quality.

Five bad filters, though, is another thing entirely. I’m completely aware, for those of you who are going to feel the need to point out the obvious, that nobody shoots with 5 UV filters. And I understand that one cheap UV filter wouldn’t have nearly as bad an effect on image quality as 5 of them. But I don’t think you can disagree that the good (and expensive, I know) filters have much less effect on image quality than the cheap filters.

BTW – before anyone asks, I avoided name brands of cheaper filters for a reason: many filter manufacturers make both pretty good, and pretty bad filters. You can tell the difference by the price or by reading carefully about the number of coatings, etc. A Tihoya $29 “high quality” filter is not the same as a Tihoya $79 “Professional” filter. This wasn’t meant to be a filter review, just a fun demonstration of the obvious.

Roger Cicala

Lensrentals.com

June, 2011

212 Responses to “Good Times with Bad Filters”

Nolan said:

As much as I agreed with the test, please provide decent pictures of the two when making a comparison, one is clearly out of focus.

Antony said:

After dozens of convincing articles like this I STILL just can’t bring myself to pay ~£50 for ONE UV filter. I’m not shooting with the frikkin Hubble telescope here. I paid £71 for a whole Canon lens (brand new)! That 50mm prime, I hasten to add, has done me proud, and I just don’t see it getting noticeably worse with a cheaper filter.

eric said:

It seems to me that you are missing the purpose of the filter as protecting the lens. You have a £71 lens, spending the price of the lens more or less on a filter to protect it doesn’t make sense. So go with a cheap filter if you must, or no filter at all.

LensRentals Employee

Roger Cicala said:

Eric,

Our point would be there’s no sense using a cheap filter to protect a lens – it reduces image quality. Plus the filter doesn’t protect the lens, it protects only the front element which costs only a tiny fraction of what the lens does. A good example is the Canon 70-200 f4 IS, where the front element costs $79. It makes little sense to buy an expensive filter to protect the front element which costs about the same as a good filter. It makes little sense to put a bad filter on the lens and reduce it’s excellent image quality.

steve said:

Both photos are in focus but they’re focused on different layers in the filter stack. The cheap filter photo is focused on the third filter in. Why? I don’t know, but it does help distinguish the individual elements a littler further into that pathetic mush of reflections…

Dave said:

I’ve not used filters for the last 20 years of photography. I had adopted the philosophy “the fewer layers of glass between the subject and the film/ccd, the better” a long time ago. I don’t buy $2,500 lenses, but I buy the mid-range lenses and stay away from kit lenses and low end lenses. I’ve never had issues with my front element getting scratched, damaged, poked, scraped, etc.

Sammy said:

For me, image quality will always be better with a filter, no matter how bad the quality of that filter. Why? Because I’m not scared to clean my filter out in the field and take shortcuts instead of waiting to get home and do it properly. I haven’t actually scratched a filter yet, but I don’t use blower brush then lens pen then wet. I just use my breath and if that doesn’t work water and/or isopropyl if available.

By the way I don’t use lens hoods often because they interfeer with flash at close range. I don’t like discovering later a good shot is ruined by flash shadow.

Also I have had a filter almost certainly save my lens. The cap got impacted slightly into the lens (or should I say filter) during transport. Shattered glass everywhere! Was very careful to clean dry only until sure it was all gone and voila, lens was fine.

CharleySDG said:

Really, really great article.

Marfie said:

I bought a cheap filter for the front of my 150-500 lens. On some shots I had banding on a particular level of out-of-focus lines (branches with bright edges, or wires) Any further out-of-focus and the banding was reduced. I did some tests and, though it did not go away, it was a lot less if I took the same shot without the filter. I have since noticed this banding on shots taken by others with long zoom lenses from 400 to 500mm. I now rely on the lens hood for protection unless I am in a harsh environment – which is not often.

Marfie said:

Thinking about the stacking of filters – with them being flat they will reflect light off their surfaces, back and forth, frequently before some of it finally reaches the lens proper. But the effect of this reflection off the front element and then back from a single filter, with the front element being convex, will (ok. might) be negligible. Though this is not the only influence the filter will have it does follow that one filter could be ok but 2 filters could have a significantly greater affect – which might still be negligible.

Wynner01 said:

To follow the logic that a lens shoots better images without filters then 5 lenses should be stacked without filters, as a control for the shots with five filters. The more layers of glass the more refraction, distortion etc no matter what they are attached to or their origin.
I keep a cheap UV filter on all my lenses in the bag when stored or transporting. Protects against dust, mud, drinks, sand, accidental rubbing, hitting, or if the lens cap comes off. In most cases you will lose less than 2% on any one shot. Most photographers are not careful enough to get 100% in the first place so you are all fooling yourselves.
If you really feel it makes a difference take it off. I bought a job lot of filters on Ebay for $52 there were 48 filters. (HOYA, TIFFEN etc)…only one was scratched and the threads damaged. I checked and they retail for over $1000 for the lot. The elitists and professionals try to encourage purchase of high end equipment, because they know it is a differentiating part of the equation that amateurs can’t afford, and therefore illustrates the quality and knowledge of the superior way. Discerning amateurs know the king is definitely not wearing clothes.
I take good and bad exposures, high and low quality shots, ones with filters and ones without. They remain a central part of my armory and I will keep them thank you. The best advice I have received yet is “fail early, fail often and fail with purpose.” If you are not failing you are not pushing yourselves…filter or no filter. you will remain mediocre professional or amateur. I often get paid for my work but refuse to become and elitist.

Wynner01 said:

Addendum:
I am also an artist and find artists are not so hung up on their equipment of the media thay use. A great or professional artist would not think to put down an amateur because he wasn’t using the best brush available ot the most expensive paint. She would encourage and help the other artist to get the best results with what they have available.
I have found in photography that there is a highly competitive and elitist attitude for those who know more or are considered professional.
They encourage the mystic they try to surround themselves with, but as time progresses equipment, technology and the availability of online tutorials and DVD instruction narrow the gap and the elitists are becoming dinosaurs. All I can say is become artists or become extinct.

Jeff L said:

50 filters at an average price of $60 is $3,000. That’s more than twice the price of that 300mm f/4 IS. So if Roger decides to rent out the filter stack, it’s not going to be a cheap rental ;-)

L glass is expensive, but relatively speaking, maybe not so much. A top-end Heliopan or B+W 77mm UV filter is $158 to $183 at B&H. A stack of 15 of them would cost $2,370 to $2,745. The 15-element “stack” in the 300L costs a mere $1,359, or about $90 per element.

And the UV filter stack isn’t even white!

h pete said:

Very funny!!Perhaps you can evaluate closeup lenses stacked(showing my age)
Shots from 5mm distance will tell all.

canomike said:

Although no one is going to stack 5 UV filters for real, this little experiment does show the difference between the low quality and high quality filters. No matter the multiple interactions between the filter, the high quality filters clearly have less negative impact than the low quality. You did not try to quantify your results or over state the findings. It is a well done test with a simple but clear and well founded conclusion. The better ones are better.

canomike said:

Rule of filters: First, do no harm.
So filters that harm the image as little as possible are better. Then come the questions, can I afford the better one, should I use one at all, do I have a specific need that needs to be met by the filter, will a stack of 50 filters protect my lens from a 9mm, etc.

Paul Sturtevant said:

First, I like the article.

Second, Canomike, I like how you put it together! Especially the comment on the 9mm! LOL Let’s get together and check that on out!

I would suggest that using a quality UV for protection ‘in the bag’ and for certain situations in general would usually make sense. Using one in higher UV light situations could also be of value. Take it off when doing work in a safe and low UV environment. And, as said above … use insurance or accept the risk if you do not use a UV filter.

Roger, this is a real fun article. I liked reading the comments. Even the comments I might not totally agree with.

Frampaign said:

Thank you. A great and simple experiment that I would not be able to afford to do, but it drove home the lessons. (A picture is worth a 1000 words, eh?). Enjoyed reading through the comments as well. Great information on which to base decisions.
Merci encore!

Olaf Veenstra said:

Funny article…

Why bother with an UV filter at all.
Protect the lens with a cheap and nasty lenshood.
Preferably a soft plastic one. It will keep you from knocking the front lens.
A plastic hood will absorb a shock where a metal one will transfer the shock energy to the lens causing damage.
For image quality you should use a lenshood all the time anyway!
UV filters are not required for image quality on a DSLR as they used to be on a film camera.

Desmond Spotts said:

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tom hardwick said:

Although your statement that ‘the idea that a high quality, multicoated UV filter has little effect on image quality’ may be true, many cameras have their lens hood’s efficiency considerably reduced when a filter is fitted (i e the front element is moved forward 5 mm or so). So expensive filter plus less lens hood = more flare. I’m right there with Dave’s post (Jan 19). tom.

Linuxpresso said:

Interesting article!

I feel confirmed, because I never used a filter on my D90 and especially not (!) for “protecting the lens”.

grubernd said:

roger, great article. but there is one difference about the filter and the frontlens element: on the spot instant service.
which is kinda crucial if you are out in the boons shooting anything that might smack a stone against the front surface of your lens. like mountain bikers, cars, little kids, etc. throw away the filter and keep going. actually you would put the filter into the recycling bin, of course. but usually you just get that stone on your head, so yes, filters are mostly useless.

Ranndy Stone said:

As a rank amateur, I am impressed by the article and the thoughtful comments. I use a Canon 700D EOS and I like photographing school fish in shallow water. Will a UV filter improve the images of the fish the way polaroid sun-glasses improve my eyes ability to see them?

Zuzu said:

Ranndy Stone:
What you are looking for is polarising filter. UV filters only filter UV light but UV is filtered in camera (as far as I know) so people generally use them for physical protection.
Polarising filters (which are used in the mentioned sunglasses as well) mute some kind of reflections.
Be sure to get circular polarising filter so it wont interfere with your cameras focusing system.

Ata said:

I have always used the UV filters on all my lens. If you use a quality one like B+W, Heliopan, Hoya, Hama, … there will be nothing wrong with image quality. In my opinion a good filter is which doesn’t any impact over image quality but does it’s duty as well and ofcourse the good filters are expensive but not as expensive as your lens’ front element.

james geyman said:

I prefer a cheap filter to protect my canon L lenses, as I often photograph southwestern US, where sandstone and sand blow with any kind of wind, and I hate the idea of scratching the front element. Most people are not experienced in replacing the front element, or shipping it off to Canon for this. In more tame environments I agree a cheap filter isn’t worth it (e.g. studio work, wedding photography, indoor portraits, etc).
Thanks for all your great blog posts. I always learn something.

NancyP said:

I missed this post earlier. Impressive stack of filters, perhaps giving rise to the “most items between sensor and subject” contest category in the 2013 PhotoGreek contests. I admit, I am a filter snob. I would go cheapie if I were to be in blowing grit, but otherwise, I just get the best multi-coated filter I can find for my largest lens, and step rings to attach it to smaller diameter lenses. I am frankly surprised that you could get any image at all through fifty filters, some of which are likely to be uncoated or single-coated.

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