LensRentals.com

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

214 Responses to “Good Times with Bad Filters”

Larry said:

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 said:

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...

Chio said:

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 said:

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

Dark Goob said:

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.

hugh crawford said:

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 said:

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 said:

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 said:

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 said:

"Stephane says:
ANY piece of glass stops almost all UVs. Why do you think any cheap sunglasses boast the “98% UV Block “sticker?"

Sorry, you are miss-informed, Glass does not stop all UV.
http://en.wikipedia.org/wiki/Ultraviolet#Natural_sources_of_UV
"Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths"

And cheap sunglasses are mandated by the government to block UV to protect peoples eyes, as there were cheap import sunglasses that had no UV block and literally cooked peoples retina causing vision loss.
http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm073951.htm
"Sunglasses manufactured with reflective, tinted, polarizing, photosensitizing lenses and meet ISO 8980 - 3 or ANSI Z80.3 for UV and visible light transmittance requirements"

Yves Rubin said:

Thank you Roger! Although a bit extreme, this is the best demonstration that you shouldn't have a filter, and if one is a careful person, the front element of the lens should be just fine for a long time...

LensRentals Employee

Roger Cicala said:

Oh, there's never a problem getting someone to sell you filters. Highest profit margin in the camera store :-)
But the point isn't "don't use filters", the point is "crappy filters are worse than good filters". Not rocket science.

lol2011 said:

LOL You guys are hilarious using the reasoning that stacking 5 bad or good filters in front of a good lens and not getting a good image as reasoning to not use ONE good protector filter. I look forward to selling you new lenses when you damage the front coatings. If you stack 5 filters good or bad to shoot you need help. Though I will sell you those too...

Scott said:

I dunno. Probably if you drop a lens, a filter is not going to help. But I used to do work that required me to move fast and not carefully, and I HAVE had filters give their lives protecting the front element and filter threads when I've blanged them against door frames, car doors and big rocks.

Bill Tyler said:

I response to Edwin Herdman's comment about the air. It's not the air as air that's the issue, it's the places where air touches glass. Any time you go from a medium, such as air, with one index of refraction to another medium, such as glass, with a different index of refraction, you get both transmission and reflection of the light. So the number of air-glass transitions is indeed significant. Lens and filter coatings were developed to mitigate this effect, which is why they are important.

bart cummins said:

thanks for the fun read & cool experiment. good points made about the uv's maybe not helping a whole lot. though i swear by my circular polarizer.

Edwin Herdman said:

Well, that's a pretty good experiment and interesting results! Though I would doubt the air portion of the "10 air-glass interfaces" matters at all to the final quality: With that 300mm lens you're already shooting through plenty of air.

@ tigrebleu74:
I used to think the same, but I've heard that it can make a difference - especially in long-range images. Propaby a polarizer is a better bet most of the time.

@ Bryan:
The main test is - how often has somebody dropped their lens without a filter and had it shatter? And then - If the UV filter shatters, how often do bits of the glass poke up and scratch the front element? Filters have no cushion for the thread, and depending on the lens that front element may be recessed a ways and small enough not to have been impacted anyway. For large front element lenses like telephotos/zooms, since most of the impact force is transferred right through the brass ring of the filter it may be more an indication the glass and lens design is strong than it is that the filter was actually protecting the front element. The only situation I could think of would be that the UV filter is hit by something protruding, and slows down the collision before shattering so that the force exerted on the lens itself is reduced, rather like a crumpling car design. But this can't be the majority of cases since most falls hit flat surfaces edge-on.

Geode said:

I have had a number of people ask why I don't put filters on my lenses, and then I ask them why would I? They respond, well to protect the lens. In 40 years of photography I have never dropped a lens, and the only time I damaged a lens was with a cheap lens the cap didn't fit well and put a few small sleeks in the coating of the front element when it was in the camera bag. On top of that, the only thing a filter can do is degrade optical quality. The only to get the very best shots out of those high quality expensive lenses is to ditch the filter, and cheap lenses, are well, cheap to replace, so if you do scratch them no big deal.

Austin said:

A couple of years ago I dropped my brand new 17-40 f/4L (sans UV filter) onto a sidewalk. Luckily, the lens hood caught most of the impact and the lens worked perfectly for the next two years until I sold it.
On the other hand, about a year ago a 70-200 f/2.8L (sans lens hood) slipped from my grasp and landed facedown on the street. I was horrified as I saw little sparkly dust on the ground next to it, but the UV filter had taken one for the team. That lens is excellent to this day.

So one could make the case for both, I suppose :)

Adam said:

I've had a filter save my front element twice. (15 years of photography) Maybe I'm just really rough on my lenses.

Jon H said:

With that stack of 50 UV filters attached, you're ready to shoot some aging TV soap opera stars.

Steve said:

I wonder what the SPF of that stack is :)

Bryan said:

I work in a camera store, and at least once a month we have someone come in that has dropped their lens. The UV filter is shattered, but the lens itself is fine. Depending on the lens, and how it is impacted, lens filters can help reduce the chance of the lens being severely damaged. We pretty much only recommend UV filters as extra protection for the lens.

Bo said:

LOL... THANK YOU - finally a great meaningful UV filter review.!

Having read all of this carefully, I will make sure never to stack more than 4 shitoya filters from the cheap bin. and I deeply appreciate the thought of renting the fine lensrentals lenses and keeping whatever expensive filters might accidentally fall off in the camera bag. Im sure nobody will notice the wallmart Haya star-quality $8.99 substitute being returned.

Thanks guys.

Bo

Josh said:

Must have been a bitch to disassemble.

Brian Zinchuk said:

Roger,
I actually did have a situation where my UV filter saved my 70-200 f2.8 VR, not once, but twice. Once, we were at the fair, and I was switching lenses. I handed it to my wife, and she dropped it, straight down onto the front onto asphalt. The UV filter shattered, the lens survived.

A second time, I was taking my shoulder bag out of the back of my SUV. I had fallen out of the habit of zipping up the large Lowepro pouch for same lens. Whamo! It fell straight onto the concrete from about 4 feet up. Again, the UV filter saved it.

On my 18-35, the UV filter also saved it as my then 18 month old dragged my camera off the kitchen table by the strap.

I am a firm believer.

Brian Zinchuk
http://www.zinchuk.ca

Scales USa said:

Although I own many filters, both very good and very cheap, I've moved away from everyday use of them. i might put one on if i'm concerned about protection from blowing sand but thats rare.

I have noticed a tiny improvement in sharpness, but with a very good filter, its not significant.

Thanks for the fun experiment!

Craig said:

I've nearly busted a lens twice. Guess what? The filter busted instead.

Stephane said:

ANY piece of glass stops almost all UVs. Why do you think any cheap sunglasses boast the "98% UV Block "sticker? The UV filter is the most idiotic filter, unless you shoot on top of Mt Everest on a sunny day. They are a relic from the days where you bought a lens for life. Today, you'll probably replace it before you'll have a chance to scratch it...
Adding a so-so filter on a good lens is like fitting your Ferrari with Ford Focus' wheels! I find if painful to watch people with good equipment exposing their $20 filter to the sun in front of their lens hood kept in storage position of course.

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