Equipment

Yet Another Post About My Issues With UV Filters

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Published May 16, 2017

This is a good filter. It is NOT the filter that was returned with the lens in question. Roger Cicala

Yes, I’m sick of filter articles, too. But I come today not to educate you, but to mock others. Because yes, people continue to try to save a few bucks by putting a cheap filter in front of their $1,000 lens. And also because they buy what they think are good filters off of Fleabay or some used place and these filters aren’t what they think. This can particularly happen when you purchase a brand that makes different filters of differing quality.

How bad can it be, you ask? Well, today we’ll show you. Because someone had a 70-200mm f/2.8 lens that had been nice and sharp and then returned it because it suddenly got soft. They were kind enough to return it with their protective filter in place.

So the first thing we did, as we always do, was put the lens on OLAF, which is simply an array of collimated 5-micron pinholes. A good lens should show and an array of small dots or circles. But this lens showed an array of glaring star flare thingies.

200mm with the filter in place. Olaf Optical Testing, 2017

 

No question, the customer was right, images from that lens had to be soft. But, just for completeness, we removed the filter, even though its label indicated it was a high-quality filter. Without the filter, it looked just like it should have.

200mm without the filter.  Olaf Optical Testing, 2017

 

Another thing we do on OLAF is slightly defocusing the image. In a nicely centered lens, the dots should turn into regular circles. This is that same lens above, just slightly defocused and looking just like we’d expect.

Olaf Optical Testing, 2017

 

Then we put the filter back on without changing anything else.

Olaf Optical Testing, 2017

 

If you have the slightest bit of visual imagination, you can probably figure out that there would be some bizarre, ugly bokeh with the filter on this lens. If you’re an optical geek, you might think that perhaps this filter isn’t really flat optical glass, it’s cheap sheet glass with a bit of wavy thickness.

There are a couple of things I should mention, just for completeness. We repeated the test with other copies of the same lens using the customer’s filter, and the results were identical. We also put a high-quality filter on the client’s lens and while there was a bit of blurring of the pinholes (longer lenses are more sensitive to filters), it was very minor.

So, if you want to know how much a filter that looks shiny and clear when you look through it can affect your images if it’s a cheap POS, well, there you go. Because if you looked at this filter, and looked through this filter, it would look just fine.

And another caution, just because a filter has a name brand on the side you recognize doesn’t mean it’s a good filter. For example, you can buy Tiffen or Hoya brand 77mm protective filters for $15-$18, or a better quality one of the same brand for about $35 , or top-quality for $70+ at a reputable dealer. The $15 filter is not the same quality as the $70 even though they both have the same brand on the side. And if you buy from less reputable dealers all bets are off because knock off cases for the higher priced filters are easy to obtain and the filter inside might not be what you think it is.

To learn more about what I think about UV filters in general, read my article on the topic here. There are circumstances where good-quality UV or clear filters are really a good idea. But there are no circumstances where a low-quality filter is a good idea. None.

 

Roger Cicala and Aaron Closz

Lensrentals.com

May, 2017

 

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. 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.

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  • Timothy Smith

    Are you one of those guys that drives with a car bra.

  • Jesse Lee

    And you continue to miss the point… never mind, just pretend this never happened. Happy filter buying!

  • El Aura

    The OP only needs to buy a new lens when something damages the front lens element (in this filter vs no-filter context). But anything that damages the front element would also damage any filter on it. Thus if there are X front-lens-element/filter-damaging events, the filterless person would need to replace X lenses (or rather the front elements of X lenses) and the filter-using person would need to replace X filters.

    What is so hard about this logic?

  • Not really. Nothing here says don’t use a filter, it just says don’t use a $20 filter. And don’t buy your filter from anything other than a reliable source.

  • Jesse Lee

    You completely missed my point. The OP said he never uses filters so I presume that with frequent use he’ll have to replace his lenses often. What does that have to do with me buying filters?

  • dale gravatt

    “If you can’t do it right, don’t do it at all” – I heard that thousands of times from my grandfather – a meticulous engineer. Roger’s presented evidence is too strong to disregard – within the described parameters. When time permits, I’m going to shoot “with and withouts” on all present lens/filter combos (gulp, over 80 lenses). Aside from your general useage, have you shot careful comparisons with your B+W’s – with and without? Many of my filters are B+W’s. So many projects, so little time. Ugh.

  • dale gravatt

    Excellent information – thanks Roger. What about Canon’s professional “L” lenses – many of whose weather resistant properties remain incomplete without the addition of a front filter? A dilemma?

  • Thom Hogan

    Technically, most sensors have microlenses as their top layer these days, which makes for a textured top, even though that’s a very fine texture. It’s the UVIR (and sometimes AA) filter that sits in front of the sensor that’s one of the issues. Yes, you coat it, but coatings are 100% effective.

  • Yeah, I think so. Some repeat testing showed I was probably wrong: this was really a cheapo Tiffen, not a counterfit.

  • taildraggin

    I tested a new Hoya HMC UV(C) last weekend – obvious impact to sharpness & contrast. Roughly, degradation is about the difference between my best (85/1.8G) and “worst” lens (35/2D) at middle apertures.

  • taildraggin

    Timely. I pulled a circa 1979 52mm HMC UV(0) that “looks great” from my Nikon FE/50 1.8 AIS last weekend and put it on my excellent DX 35 1.8G/D3300 beach camera. Lot’s of gritty dust at the beach shooting daughter’s volleyball games so it makes sense to put a filter on. How bad could it be? In the same geek moment, I was checking out my new 50/1.8G and compared images. The 35mm, wide open now had green fringing around *all* sharp, contrasting edges and contrast was down. Wow, that is a REEELY BAD filter. Looked perfect. Pulled the filter and was greatly relieved to get my lens back.

    This prompted me to check all my len-filter combos, pretty thoroughly. 1) all the filters had a noticeable sharpness/contrast impact. The best (singh ray, B+W, high-end Hoya) were tolerable-to-modest. 2) Old film era filters are suspect. You wouldn’t believe how bad the old Hoya was. The new HMC UV(C) had only modest (acceptable) impact.

    This confirmed what Roger writes; use only when needed as a dirt cover. This means 2 things to me the mid-level Hoya HMCs are bottom line acceptable, but also the ones I want since I’m only going to use them in dusty conditions.

    I also use hoods to block bumps – I don’t know if it’s helped, but haven’t scratched a front element in 40 years of (amateur) photography and if they stop any stray light, all the better.

  • Mosawr Team

    Thanks for the article. Shoot, this means I need to change my cheapo Tiffen UV filter.

  • DrJon

    These days is it the sensor glass or the sensor? One is much harder to coat. With the Fujis when shooting into the sun you can (rarely) get an (annoying to remove) patterning effect on images that appears to be from a reflection of the sensor, not the sensor glass?
    Example: https://www.dpreview.com/forums/post/59383192

  • Ben Brayev

    any idea if the compatible 105mm protective filter of the new sigma 500mm f4 is as bad as the rest of them?

  • Bob B.

    I buy the best lenses that are available when I can afford them. I put the high quality B+W Clear MRC Nano filters on them.
    I get:
    Great images
    Peace of mind
    High resale value
    It’s a personal choice. If I have a great shot. No one asks if I had a protective filter on my lens. Ever.
    I have never had images where I think that there is a problem and where my B+W filter was the cause.
    🙂

  • What he said. Thank you David!

  • Claudia, I’m going to go buy a bunch of filters and do this with all of them. It’s a fairly crude test, but at least should give us a ‘pass-fail’ kind of grade on them.

  • Yes, I once had an L37c UV filter shatter and scratch the front element of a 105mm Micro Nikkor when I tripped and my Nikon hit the pavement. It was in an unpadded backpack, and the lens cap was on. The lens had a rather inexpensive fron element. I think it was only $25 at the time, about 1992. Since then I have not used protection filters regularly.

  • Claudia Muster

    Very impressive, indeed. It would have been interesting to also see an OLAF picture with a quality filter for direct comparison. (I’m aware that you have published MTF curves in the linked article and didn’t find any degradation worth mentioning.)

  • david

    I’m confused by the anti-filter absolutism of some of the comments. I think this excellent article proves indisputably that bad filters can massively degrade image quality. At the same time, Roger has also said, “A good filter should avoid most (not all, but almost all) effects regarding ghosting, flare, and reflection. It shouldn’t affect sharpness even at the highest level of measurement.” He has shown MTF evidence demonstrating that. And he has pointed out that the rising cost of lens front elements makes the use of filters more of a judgement call. Using or not using filters is a practical balancing act, not a religious belief.

  • jrconner

    I don’t have OLAF luring in my basement, but my rough and ready tests, and Roger Clark’s at clarkvision.com, confirm R.C.’s observations. Unless I’m shooting in a sandstorm or in similar conditions, I do not place a protective filter in front of the lens. And I don’t use a polarizer as much as I used to.

  • Carleton Foxx

    I just meant their Plain Jane 77mm NC clear screw on filters. Apparently Nikon is not doing a good job of making it known that they even have them available.
    I won’t even ask about the effects of their old radioactive soft-focus filters….

  • El Aura

    You might get better images with a damaged front coating then with a $30 filter.

  • El Aura

    And you are buying filters often? I bet if you do a survey of people using filters (for protective purposes) and ask them how long on average their filters last, I’d say the vast majority will say that they never even replaced a single filter.

  • El Aura

    How large was your usual viewing size with film and how large is it now? The largest prints of my film photos is smaller than my current monitor. And I don’t even have a 4K or 5K monitor, having one of these will further increase the amount of detail I can see, in particular since large prints tended to be looked at from a larger distance than the typical viewing distance for computer monitors.

    Plus what Thom said about actually getting an IQ benefit from an UV filter during almost the whole film era. I had UV filters during the film era but after I did not manage to damage the surface of a single one during about 20 years, I decided that filters were an insurance with a very bad cost to benefit ratio (benefits being the saved lens repair costs multiplied with the probability of an incident occurring). There are other insurance-type situations where I get a much better benefit to cost ratio.

  • Thom Hogan

    It’s an excellent test for eyesight, too! Find some small LEDs and focus on them from a distance with that long lens. Then check the smear with and without the filter. Both in focus and slightly out of focus as Roger did with Olaf.

  • Thom Hogan

    Might depend what filter you’re talking about. For example, Nikon designs some of the exotic lenses with drop-in filters so that the filter itself is part of the optical formula (i.e. you need a clear placeholder there if you’re not using one of Nikon’s drop-in filters).

    If you’re talking about front-of-lens filters, then I’m not sure.

  • Thom Hogan

    Yes, this is one the things I mentioned in my article and got lots of flack about. But I’ve seen it multiple times in the field where a drop causes the filter to shatter and the shards scratch the lens front element. Then the argument starts “but without the filter the lens would have shattered…” No, it wouldn’t. This gets tricky because every lens is different, but there usually is a cost difference between repairing a lens that has front ring and alignment damage from a drop and one that needs the front element completely replaced.

  • Thom Hogan

    This has long been an issue with digital: there’s a flat piece of glass sitting over the sensor. Originally, it was highly reflective. These days, most of the camera companies have addressed the reflectivity some, but it’s still reflective. What they also have been doing is to reverse coat some lens elements so that you don’t get that bounce back of pinpoint sources like that. But most filters don’t do that. So any light that reflects into the back of the sensor—and some of that may even come off the front element of the lens, despite coatings—can cause this issue.

  • Thom Hogan

    “Indistinguisable.” Perhaps indistinguishable to you, but perhaps not to others. That’s the real problem here. We get a lot of anecdotal “don’t see any difference” reports. I get those with filters, lenses, sensors, raw converters, you name it. Trained eyes see something different than untrained eyes. And measurements say something different than subjective evaluation.

    As for film, we used UV filters until the 90’s because film had a significant UV response. So as you moved to higher altitudes you got different results. Somewhere in the 90’s most films stopped having significant UV response. DSLRs have had UVIR blocking filters over their sensor from the beginning. There is no significant UV response in a DSLR that hasn’t been modified.

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