Roger's Ramblings

Good Times with Bad Filters

Published June 1, 2011

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

Author: Roger Cicala

I’m Roger and I am the founder of Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in Roger's Ramblings
  • dlj

    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.

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  • jean

    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.

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  • RHB

    How do the Ultraviolet (UV) Pro 1 Digital Multi-Coated Filters and Ultraviolet Clear Pro 1 Digital Multi-Coated Filters stack up against the more expensive B&W tested above? I’ve read the Hoya Digital Multi-Coated are supposed to be just as good. That’s mostly what I’ve been using and I certainly don’t notice any issues. I’ve used B&W but I don’t like the caps on their thin filters and their polarizers are bumpy and hard to clean. So I’ve stuck with Hoya and like the price better as well.

  • Roger Cicala

    Akira, the price varies depending on the lens. Some are more. Some quite a bit less (the Canon 70-200 f4 for example, the front element is $83). In general wide angle lenses have more expensive front elements.

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  • sinan

    Creative experiment, thank you Roger.

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  • Akira

    Can you get a front element replaced for $150 as Roger states? In that case, the cost of a good filter doesn’t make a whole lot of sense except that you’re without the lens during the repair. Also, in the case of a drop, I think that the filter ring protects the barrel, which is why the filter shatters when dropped like that (it happened to me when a lens rolled out of my bag). A barrel replacement will be more than $150. Of course a lens hood would prevent that problem. I like to use a (low-profile) filter on my 10-22mm though. The front element moves within the barrel, which means that the inner parts of the barrel can be exposed. Also, the front element isn’t a flat piece of glass like it is on most lenses.

  • Michael

    There seems to be a lot of debate on whether or not a filter really does protect a lens, and a lot of anecdotal evidence supporting both those who say either that one does or that it doesn’t matter. I won’t join that debate.

    I will point out, however, that whenever I see a lens for sale on ebay, the condition of the front lens element is very frequently an issue (whether advertised by the seller or inquired upon by the buyer), and that lenses with even very small scratches on the front lens element seem to sell for somewhat less than those which don’t. Indeed, a selling point often seems to be whether or not that front element was protected by a filter during the ownership of the lens.

    What I take from this is that whether or not a single UV filter actually does matter when it comes to actual lens protection, it may, on the other hand, count for a great deal when it comes time to sell the lens, especially for more expensive lenses where the buyer is likely to be more critical of the lenses’ condition. When it comes to selling, buyer perception is everything, whether it is grounded in practically reality or not.

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  • Paul Lazzaro

    Back in the analogue seventies, I worked in a camera store, and we used to check filter quality by holding them almost horizontal, then looking at some distant object through the maximum thickness of glass.

    The amount of ‘rippling’ was often substantial, and with ample stocks to look at/compare in moments of boredom it was fairly clear to see which big brands at the time were buying their glass from the cheapies and re-branding it!

    Nikon and Leica were always first class, and I recall Hoya was the first independent whose stuff also measured up well, and were also early into multicoating their range/slim mounts as well.

    It was all too easy to jam stacks together, so a little hacksaw notch diagonally across the front and back rings meant you could
    always separate them. Today’s useless fact!

  • Rol

    Good article Roger and supplementary explanation JeffT (June 16, 2011 at 7:49 AM).

    I think some of the reasoning specifically about the use of UV filters could be a hang over from film. I have certainly used quality UV filters with film to fractionally ‘warm’ a picture by reducing the high end blues.

    As for lens protection, when out and about, multi-coated lenses (compared to a filter) are tricky to keep clean, so I’ve often used a UV or ‘skylight’ filter for convenience. A couple of times the filter has taken a scrap, so I’ve been able to replace it and continue shooting.

    Interestingly, the only lens I have where the front element has been damaged, was damaged whilst being repaired by a professional service some years back. Unfortunately as it was expensive and discontinued many years ago, I’ve as yet not found a suitable replacement…

  • Jure

    I use only cheap filters. You must admit that by using only one filter it is almost impossible to see the diference and that 99,99999% of hobby photographers use more only one or – better – none.

  • Robin

    The real comparison is between one expensive new filter and one apparently perfect 20 year old Hoya bought at a camera fair for 2 or 3 pounds or dollars which is the only sort of filter many people ever use. Pity this key test wasn’t done.
    What was interesting was how bad 5 expensive filters were. Many zoom lenses consist of 15 or more elements and yet give state of the art contrast. So what’s the problem – the coating or the flat sufaces? Pentax used to make a slightly curved ‘ghostless’ UV filter, convex at the front and concave at the rear to combat known defects from the use of flat glass surfaces.
    The main purpose of a filter used to be to avoid fingerprints/rain etc reaching the front lens element and subsequent cleaning damaging the coating. Also some lenses had ‘cold’ transmission (which really mattered when you were using Kodachrome) and many photographers wanted to warm them up with 1A or 1B skylights.

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  • Uncle Toopula

    I want to see multiple choice 100% photo crops where the viewer has to pick a) shot without a filter b) shot w/ a single b+w UV c) shot w/ a single el cheapo UV. Finally, d) shot after front element is scratched up.

  • Larry

    I am surprised that Roger would not install a filter on the lenses they rent out if it were up to him.

    Doesn’t the fact that Lens Rental does this already indicate that there are benefits to using the right filter, i.e., the high quality filter? Why buy all these filters if not to protect the lens? Why suffer through the indignities of receiving of receiving the lens back with cheap filters after the customers took out the expensive filter and replaced this with cheap filters?

    Then there is the matter of cleaning. It is s much easier to clean the filter than to clean the front element of the lens. Even with just 2 or 3 filters at the end of a hard day, it is so much easier to clean the filters than the front elements of the lens. Imagine how the task looks like when one has to clean 50 front element in the lenses versus 50 filters. The space occupied and the weight involved makes cleaning 50 lenses a daunting task not to mention require a considerable storage and working space. Cleaning 50 filters is much easier and can be done within a small space.

  • Bruno Z

    Seems like this whole everlasting “filter for protection” debate could arguably be subdivided into 2 different issues: dirt & smudges, and accidental drops.
    Regarding the first, obviously if you have the habit of getting your front lens so dirty that you feel the need of a filter, so be it.
    Now for the second crowd which is just using it as an insurance against an accidental drop, why don’t you guys just leave a step-up ring on the lens? No detrimental optical effects (on the contrary, shades a tiny bit), oh-so-cheap, and the bendable aluminium will protect your lens rim as well if not better than any filter. If your lens falls on a stick bit on the frontal lens itself, then I believe that filter or not the damage will be the same, the filter glass itself is very thin with straight faces and offers very very little mechanical protection…

  • Excellent. Though I would’ve like to see examples with only filter too. My camera fell down from a tripod, luckily with the cheapish 17-85mm I got, and the filter was completely broken. Nothing happened to the front element of the glass.

    As for lens caps – I rarely use them, so it’s nice to have some protection.

  • barry

    Unfortunately, when I dropped a lens the filter shattered and damaged the lens by scratching the front element.

  • Dark Goob

    Even a crap filter will often save your lens if you drop it. The aluminum ring (or brass on B+W) compacts nicely and translates the shock into the glass, which typically shatters radially but not inwardly. More than five times I’ve seen a lens come in for repair which had been saved by the filter in this manner, usually without even damage to the filter thread on the lens. So, at least on a big heavy lens, I’d put a UV filter, even a cheap one, instead of nothing… just in case. But on a pancake lens or micro four thirds 14-42 Zuiko, etc., there’s really no point… the lens opening is so small and non-protuberant that it’s very unlikely to be impacted by something.

  • If you really want to use a filter to protect your lens when you drop it, buy the cheapest filter you can, preferably with a threaded ring made of brass or anything that is not aluminum, remove the glass, and screw the ring onto your lens. Lens shade work even better of course.

  • Jon

    Forgot to mention, every pro I’ve ever known lost their lens caps years ago. I was assisting a friend at a wedding the other day. I went to shoot while he set up some light and had to laugh out loud when I saw that none of his lenses have front or rear caps. Yet his images are stellar.

    Mind you his cameras and lenses spend a lot more time in the shop than mine do. Apparently he finds that preferable over taking the time to protect the gear.

    To each his/her own.

  • Jon

    I work at a camera store. I see at least half a dozen customers EVERY WEEK who come in to replace a damaged filter. Some have been damaged when something ran into the filter. Others when the camera was dropped. Most when cleaning it.

    A good lens hood is a better solution to prevent damage when a lens gets dropped. A stepping ring is next, as it deforms easily in the event of a sudden impact. A filter is less effective, but still helpful. Nothing on the lens obviously means no protection.

    As anyone who has ever realized long into (or after) a shoot that there was a big fingerprint on their lens can attest, the front element has little impact on the final image quality. But even a cheap filter on the front of the lens (which, again, has very little impact on IQ) will provide a lot of protection in daily use. I see it all the time with customers, and I’ve experienced it myself.

  • Dilbert

    Roger, I’ve once dropped a camera with lens attached, lens first. The lens had a UV filter attached to it. The UV filter was shattered. I don’t know what would have happened if I hadn’t of had it there, but I’m not in a rush to try it out.

    I’ve come to rely on the lens hood for protection as much as or more than the lens cap. When it’s slung over my shoulder and I’m bush bashing, every extra bit of protection helps. Why isn’t it in a bad? (1) full of lenses (2) take too long to get out and ready if something happens

  • James
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