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


June, 2011

214 Responses to “Good Times with Bad Filters”

jean said:

I use now the cheapest uv filter 5$ from ebay for all my lenses, then when on a shoot I unscrew the filter take the shots and rescrew it to maximise quality. I paid 150$ in the past on a b&w and it would everytime get a little blurry, on all lenses L,prime,zoom. returned it to check and it was according to them the normal standard. unless weather
condition is bad or in a place with lots of people, the only use for me is to protect the front element in case my cap goes off.

dlj said:

I stopped using UV filters when I went digital years ago, and haven't regretted it other than *one* trip, at very high altitude, where the UV created a noticeable haze increase with distance. You don't get many opportunities like that, so remember that the default UV reduction on modern digital cameras doesn't handle all amounts of UV, just the most common amounts. Oddly, other trips to high altitude (but not as high altitude) didn't show the haze, so you have to be really up there (4-5+ km) to experience it.

Terry Byford said:

A great fun experiment. I have always used a filter purely for lens protection. Get scratches on that front lens element and then shoot with a light source either directly or obliquely shining into it and you can often say "goodbye" to decent pics from your expensive lens.
A few years ago I bought a Sony R1 for its fantastic Zeiss lens. Thinking I could save money, as it takes a 67mm filter, I bought cheaply only to be horrified when pointing the camera out of a window to see a staggering amount of reflections that the filter's coating couldn't suppress. I took the filter back and waited 3 weeks whilst the store sourced a "proper" filter for me at 5x the price. But it worked. Nuff said, I think.

Mark said:

I was always taught to spend the money on the lens. Protect it with a filter, but when it comes time to shoot take it off. Lenses are expensive, why put even a $100 UV filter on a $1200 lens....doesn't make any sense to me.

Mike said:

More than one person has said they use a filter for protection, but remove the filter before taking the photo.

I do the same thing, but I use a lens cap for protection, not a filter.

Steve G said:

I once picke up a 70-200 Minolta 'beercan' tele for free because the guy 'never got a good result with it'

Long story short - I took off the 'store brand' UV filter on the front and - shazam - excellent results...

Jessica said:

Personally, I prefer to leave a polarizer filter on my lenses as the "protective" filter. Since I usually want that on the lens for the photo itself anyway, it's just easier to leave there and take it off when I don't want it on.

Tord S Eriksson said:

I do mostly use UV filters, and if I could afford it, only Heliopan! But some lenses work better without - taking shots of the moon improved without, but Heliopan's marvel that blocks both IR and UV cost as much as good used lens!

Craig Kozloski said:

More evidence to continue using a lens cap and hood. Not a single scratch in over 30 years.

Somewhere on the web is a page with photos taken with badly scratched front elements. Guess what? Most of the images looked great. The worst case for most scratches is reduced resale value.

Rich Gibson said:

Up till recently I did not use protection filters. I switched recently to using them. On a trip I was putting a sling mounted D700 over my shoulder but the sling slipped through my fingers and the camera and 17-35 dropped to the floor in a store. Gulp! The protection filter absorbed the drop and bent onto the lens sticking fast to it. The shock passed into my 17-35 and broke it. I'm out the filter and several hundred dollars for repairing the lens.

No I didn't have the hood on the lens; a lesson I will never forget.


Frank Bosco said:

I use Leica UVAs, B&W UVs and Hoya HMC UV(0)s on my Leicas, Pentax's and Nikons......not a dimes worth of difference between them....On my Rolleiflex, I can't see the difference between no filter and the Rollei U-V Bayonet II....so my working assumption is that one UV filter has no effect no matter which one.....

Antonio said:

Great article.

I have never used UV filters (I use others that are useful for what I want to obtain). For protecting the lens I use something I call a "lens cap" :-) 20+ years, never have had damaged a lens.

The UV filter thing seemed to me like something the store guy tells you and then gets to be "general knowledge". Everytime I bought a lens, they wanted to stick a UV filter on it. No thanks, do not see the use of it, to protect the lens they say, no thanks, I will take the risk. And this article shows it is even worse to use them, you spend $1000 on a lens for the little extra sharpness, throw a UV filter and the reason to spend that amount of money is gone.

Paul said:

I only use a CPL or an ND when I need a CPL or ND. The "protection filter" thing started in film days as a great way to make a profit because stores didn't really on lenses. Today there are 10x more customers.

Anyway, go get your UV protection filters and toss them into the lake. They do a very bad thing to your inage: attract flare like bees to honey. That's a MUCH bigger problem with digital due to sensor sensitivity.

Protect your lens with th ebest thing available, a lens hood (glad all L lenses come with one). Besides the glass being set way back, you are guarded from any stray light across your lens which causes flare and decreases contrast. My $2500 Canon 70-200mm/2.8 is insanely good at transmitting contrast to the sensor, BUT ONLY WITH A LENS HOOD IN PLACE. If I ruin it with even a "good" UV, then what's the point? Better to go buy a $300 Sigma.

Last thought: you might ask "But what about shooting in the daytime at high elevation, there's haze, don't I want to remove that with a UV filter?" Answer: The problem is not the midday haze, the problem is that you are shooting at midday. If you need a UV filter, you're simple shooting at the wrong time of the day. If you want top-level photos, it is ALL about the light and the quality of your glass. If you want to shoot at midday, get a Point-n-Shoot to record your memories. But for a pro lens, destroy UV filters forever, attach your hood (YES, even indoors) and shoot when light is gorgeous, and you will succeed.

SW said:

My two bits: believing that more glass surface means more distortion, I ran a series of personal test shots off a tripod using a 24-105L Canon 77mm lens: lens only, UV Hoya filter (more expensive) and UV Quantary filter (cheaper). The shots were long-distance across an urban valley.

The with-filter shots were sharper than without. The Hoya edged out the Quantary by a tad.

Paul said:

Whoops, I should have provided an example: http://www.betterphoto.com/gallery/dynoGallDetail.asp?photoID=11517631&catID=45873

This was shot with NO filters. Had I had a UV I would have had flare all over the place. The sharpness and tone and contrast come from that Canon element staying pure as it inhales the light. Please destroy all UV filters, lol!

Wait, one exception: if you're at the coast and it's windy and sand and sea spray are flying all over, yes, you want to truly protect that lens in that situation.

Geert said:

I won't go into the image quality part, but there are two practical reasons to be weary about UV filters:

1. A high quality UV filter often is about as expensive as a new front element

2. A filter damages MUCH easier than a front element.

I find a decent lens hood works very well for protecting a lens from accidental bumps and knocks.

Jeff B said:

I never use a filter on any of my fine lenses, including Leica, Canon L, and Nikon. I do however, encourage all others to use them, even if they ruin the images because I might someday buy one of their lenses on the used market and appreciate that many of the old lenses have like new front elements because the original owner never took the filter off :) . Like others that have commented, I have not scratched a front element in more than 30 years of photography and I NEVER shoot with a filter because I want the ultimate contrast my best lenses can provide.

John Stone said:

I'm a big fan of using high quality filters as protection for my lenses, despite the cost. One of my hobbies is astrophotography. Astrophotography requires long exposures, which means that the lens and camera are exposed to the elements for hours at a time. During the course of this process on cool nights during humid times of year, dew can be a serious problem, or frost in winter. Some lenses are only fully weather sealed when a filter is in place. The first time you have to put a lens in a heating blanket, leave it in hot sun, or use a blow dryer to heat it up to dissipate condensation off of internal lens elements, you quickly take on a more serious attitude about these issues. I often use dew heaters and lint-free towels wrapped around the outside of the lens body to help combat these problems, but sometimes mother nature wins anyway (cable gets unplugged, dew heater battery goes dead, too cold too fast, etc).
Besides astrophotography, I love doing landscape shots. These are often in imperfect weather, on rocky or mountainous terrain with wind, snow, sand, blowing dust, or other environmental challenges. I find it a heck of a lot easier and less nerve racking to remove a UV filter from a $1800 lens to clean it carefully than to have to do the same on the lens itself. I can keep an extra UV filter in my bag that's cleaned and ready to go in case the one on a lens gets soiled. I should mention that I _always_ use the lens hoods on my gear, both to stave off the sand and dust, the dew, and to avoid reflections from bright sun etc. I end up having to clean the lens hood and filters regularly, but my lenses have no scratches on the front elements, yet, and there've been a few times when I would have missed a nice shot if I couldn't have quickly removed a soiled filter and either shot without it, or put on a clean one.
If you shoot without a filter, when the front lens element gets soiled, you have no choice but to either shoot anyway, or stop and try to clean it quickly. Cleaning too quickly/roughly is exactly how a lens coating gets scratched...

tbyrd said:

I never use filters... I understand the argument for 'protecting' the lens but I never understood why anyone would want to put cheap glass in front of their lenses.

BTW, Jeef B's post (above mine) is spot on!!! I hope everyone else uses filters so I can buy your lens from you someday!!!

Rick said:

I can't find one for my 500mm. Should i duct-tape a piece of safety glass on the hood?

Andre Oliveira said:

Thank you for the article. Very instructive.

Joakim said:

Pretty damn enlightening!
I'm new to (SLR) quality photography, and all this makes me glad because I won't have to put lots of money on filters, just little money on lens hoods! :) I will now save the filters for the beach!
Just one thought: What about polarizing filters? Seems a lot of pros use them for improved image quality of water and sky etc? Do they pose the same problems as UV filters? (They should?)

Harry said:

I've switched to B&W filters, and have experienced no problems ever since. If there's no CPL filter on each lens, there is a UV filter.

lyle said:

Good way of producing fog. lol


Brad said:

Nice test. Simple :)

Can you do part two with some harsher lighting conditions? A bit of flare, or something with some chromatic aberration?

Joseph G said:

As a slight clarification-

UV Haze filters and Skylight filters are NOT the same filter.

UV Haze filters are absorptive of the ultraviolet portion of the wavelengths of light spectrum. Thus, they remove the haze often associated with higher altitudes. Haze filters do this by blocking the UV spectrum light rays that do not focus at the same point as visible light rays do. This is the same thing as the UV filters/protective glass on Halogen lights (as Halogen as a light source produces a high and sometimes dangerous level of UV spectrum rays). This is considered a cut-off filter. Light with a wavelength above a certain point is not passed through to the film/sensor.

Skylight filters, on the other hand, are absorptive of visible light in the higher level blue/indigo range, but do not necessarily cut out UV light. They are effectively a form of subtractive color mixing, similar to FLD's that balance out fluorescent lights, used to make an image more appealing. Averaging less than 1/5th of a stop reduction in light transmission, they appear clear in casual observation, but closer inspection or viewing at an angle proves that they have a salmon or bastard amber tint.

As most digital cameras have a built in filter over the sensor cutting out most UV and IR light, the non-protective qualities of the UV filter are usually rendered moot. The same goes for the skylight filter, as the white balance engine in digital cameras or RAW processing software can compensate/be used to compensate for excessive blue in images. Even simple tweaking in image editing programs will work for this purpose.

John Gore said:

Nice article, and interesting comparison. I have to agree with the comments above:
-I dont use filters (due to quality loss, etc), although if I did I would only use the best quality ones as the article recommends.
-I do recommend that others use filters to protect the lens and "protect" resale value (although I have never damaged the front element of any of my lenses).
-lenses filters DO make a difference to contrast, sharpness, lens flare, etc.
-keep the lens hood on, and clean the front element regularly = best image quality.
PS: If you use a filter, notice how much dirt gets stuck between the filter and lens element? Now you have 3 surfaces to clean regularly! :P
Each to his own, thanks for a great article! :)

Ilias Theodoropoulos said:

What will happen if you stack some x2 tele filters? Will that work? Will it focus?
Will you consider this for your next "free time experiment"?

MLWadester said:

Lolz, @Uncle Toopula. I enjoyed the blog post, thanks to DPReview for posting!

John M said:

Great fun test, but one thing that no-one has mentioned is that a filter being further away from the front element than normal will change the effect it has on image quality.

Now I'm just trying to work out whether that would be for the better or for the worse!

Photofaculty said:

As well as the photographic results, could you try this with circular polarising filters and do a video of how you put them all on and then how you get them all off again ?

Harald said:

Are you planning to rent the 'stack' of 50 filters for Soft Focus Potraiture just like David Hamilton :-)

Urbanphotographer said:

I enjoyed the article! Thanks! Keep it coming.

@photofaculty that's a hilarious and superb idea •lol•

Donkemaen said:

In the two shots comparing a stack of expencive filters and a stack of cheap ones.
On the stack of cheap ones, the first filter should at least look SHARP! it looks out of focus.

Carl said:

John Stone, yours is some good advice. I would like to see some of your images.

Carl said:

Tigrebleu74, yours is an example of why forum and blog response posts are less than useful at times. People tend to feel the need to weigh in on something, and then get it wrong. Then no one corrects them, and assumes their statement is fact. You state that "There is already an excellent UV filter on the sensor of most digital cameras." Actually, the filter on the sensor is a HIGH PASS infrared filter (as opposed to a low pass UV). Cameras which have been "modified" for infrared use, have these filters removed. But there is no UV filter on a digital sensor. I'm surprised Roger didn't correct you.

Diego said:

Very interesting article, i have some friends that buy a 1500 dlls lens and then buy a 15 dlls filter, and they have the brilliant idea of stacking a UV, and a ND from the same cheap brand, and cry because they dont have sharp images.

Ashley Groome said:

I never cease to be perplexed, by seeing a person of good, common sense, spending a couple of grand on a decent body and possibly as much again on a decent lens - and then get all bent out of shape because they have to pay 80 or 90 dollars for a decent UV filter. Go figure.

Piechie said:

Love it Roger - I actually got the link to this form an Adobe Lightroom FB post!

Glad things are going great for ya! We we going to go out shooting again?

Gary Edwards said:

Good test. Valid approach to gain observability of the effect.

RebelPhoton said:

This was actually a great opportunity to explain how the MTF of an imaging system is a result of the multiplication of all of its elements. So you might not ordinarily notice the difference in quality loss between a filter that lets through 98% of the original resolution and another that lets through 92%. (I'm making these numbers up).
But if you stack several similar filters those differences quickly add up:
So there is a very noticeable difference between a 10% loss and a 35% loss. This makes it easier to measure the difference between different brands and models.

Carlos said:

Rebelphoton has a good simplified explanation. The 5 stacked filters amplify the loss in picture sharpness to a point that our eyes can perceive the decrease in quality/sharpness of the pic. But if you compare two pics with only one filter of each kind, the results could be inconclusive to the naked eye, but yet measurable with the proper instruments.

Taylor said:

Well, it depends on how you plan to use them. Filters are great when you know how to use them and when to use them.

John Kim said:

Hey, great article. Makes me wanna chuck all my cheap filters.

BADigiFoto said:

The comparison photos with the view through the cheap filters reminds me of the countless cheap commercials running after midnight on commercial TVs, addressed to mostly intellectually challenged shoppers who can be fooled with the least bit of effort that they actually need the crap sold to them and they are getting getting a promotional (just now, just for you, but wait, there's more...) type of deals.
If you truly are serious about making such comparisons, shouldn't you guys pay a little more attention to the correct exposure of BOTH images? I'm asking this question because I would like to assume that you haven't purposefully made the expensive filters look sharper and the cheap ones unsharp, poorly exposed.
Those of you who are not sure what I'm talking about feel free to look at the black frame of the first filter - not just that you can't see through the first one properly (incorrectly blamed here on the quality of filters), but you can't even see the outside edge/frame of the filter either, which clearly can mean only one thing: the photo was poorly exposed.
And as long as there are such clear "mistakes" (as again, I wouldn't want to call them deliberate deceptions), the trustworthiness of the entire post can be seriously questioned...

Tim Harris said:

That's great guys! Really appreciate it. I was actually coming to the site to look for filters for an upcoming project. As always, you've gone the extra mile to help us out! Thanks for posting.

CCycomachead said:

Many people forget some of the other advantages of filters.

Weather Sealing. Having a filter on not only protects the front element and the lens barrel / body if dropped, but also prevents dust moisture and other debris from entering the lens, especially if the front element moves.

Yes, you can buy weather sealed lenses, like L series, but most L lenses aren't fully sealed unless they have a filter, and yes the 24-70, 24-105, and the 16-35 all require filters to be sealed.

As far as the cost: $100 on a filter should be about right for the price of a thousand + (or even less really!) dollar lens. That's one small piece of glass compared to the whole lens (and is a hell of a lot easier to manufacture!) so it's really spending an 'appropriate' amount.

The filter as a lens cap idea is neat, but it all depends on how you use it. If I'm walking around and keep the lens cap on and do need to take a photo 'instantly' my lens cap is either off (and the lens is protected by the hood) or it takes me half a second to pull a cap off. If I'm rushing and I drop the cap or something is what $10 or less to replace? If I'm always taking a filter on and off I'd be worrying about the quality of that filter and that it'd be protected, because I still wouldn't put a cheap filter on as a lens cap (because I'd be worrying about the images that got taken with the filter on). Also, I can tell through the VF if a lens cap is on, but not if a filter is.

There are also some lenses, like my 50 f1.8, where buying a quality filter doesn't matter. The cost of the lens doesn't justify the price of the filter. (Also while that 50 is pretty darn sharp on it's own, its own glass isn't as nice as my 24-70 so I have a feeling that it would be more adversely affected by a filter. Though I could be wrong about this.)

Finally, the more glass you have the more problems you are bound to run into. It's physics, but that doesn't mean that clear filters aren't still useful.

Hugo Chikamori said:

Now...can we try that with 50 crappy 3 stop ND filters. I'll see you next year for the result. It may take a month for the shutter to finally click. ~evil laughter~

Hugo Chikamori said:

Actually, Roger. I've got an idea for you. Stack 50 3 stop ND filters on the camera...stick the camera in front of a sloth enclosure at the local zoo...and then come back for the result in about 2 and a half hours. I'm sure you'll get a picture of some speedy sloths.

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