My Not Nearly Complete, But Rather Entertaining, Circular Polarizer Filter Article

Published September 15, 2017

So, a while back I wrote a not quite complete article on UV filters. To do that, I had to buy new testing equipment and learn to test filters. This was not what I wanted to do when I grew up. But somebody has to do it, and I did get to buy new toys.

More importantly, Tyler (Who handles the purchasing) asked me why, many years ago, I chose the Circular Polarizing filters that Lensrentals stocked. A better person than me would have confessed that I’ve never known the first thing about Circular Polarizers; that I just bought the most expensive to be our ‘best’ and the cheapest to be our ‘basic.’ But instead, I just said, “Well, we should do some scientific-type testing and a more thorough evaluation now.”

Like a metaphor for my life, the results ended up being the opposite of what I expected. I thought if we found tons of differences testing simple clear and UV filters, there would be many more differences in more complex polarizing filters. So today, instead of showing you amazing differences between the various brands, I’ll just save you some money on your next CP filter purchase. That should work out for both of us: you save money, I get a shorter blog post.

I should mention our methodology has improved somewhat since we did our first filter article. I used a red laser to measure transmission then, and several people made the very reasonable suggestion that a green laser might be a better choice, being in the middle of the spectrum and all. Other people said I should get a spectrometer and measure the entire spectrum. So I did both of those things.

This should give you some hints about me as a person. If someone asks me to test a lens at a different aperture, I have a screaming fit about testing taking up a few hours of my time. Someone suggests I spend $15,000 on new equipment, and I’m like, “Yeah, great idea, that would be cool to have.”

Finally, I had no intention of testing every polarizing filter on the market. I did what I usually do; bought the ones B&H Photo had in stock in 77mm size. So we’re going to compare, in no particular order, except alphabetical, with the current price for a 77mm:

  • B&W XS-Pro High-Transmission Circular Polarizer MRC-Nano         $102
  • Heliopan Circular Polarizer                                                                          $200
  • Marumi EXUS Circular Polarizer Filter                                                     $140
  • Sigma Water Repellent Circular Polarizing Filter                                   $150
  • Tiffen Ultra Pol Circular Polarizing Filter                                                 $103
  • Zeiss T* Circular Polarizing Filter                                                               $180

So, About the Polarizing Part

If you’re thinking about buying a circular polarizing filter, you probably want to know which ones polarize the best and which ones the worst, right? I know I did. Now we could have just gone outside and taken pictures in the bright sun and said this one’s good and that one’s bad. But we never do anything simple when we can complicate the crap out of it.

So what we did was take our laser transmission set up and modified it a bit. Primarily, this shines a laser into a power meter and gets a reading. Then we can stick mostly transparent stuff in the beam and see how much it reduces the power reaching the meter. Excellent lasers are almost entirely polarized, but I have a budget, and that budget didn’t include (much to my sorrow) $10,000 for the lab-grade, steel-melting laser I wanted. I got a little 5-mwatt green (530 nm) diode laser.

It’s sort of polarized. So we shined that laser through two sheets of polarizing film, each of which have a 1,000:1 polarizing extinction ratio. So basically, the light that passed through the film was really, really polarized. Then we put the filter in the beam of polarized light to see how much light it let through in the open position. For now, we’ll just call it ‘most of the light.’ Finally, we moved the lens to the polarizing position, which should have blocked all of our polarizing light if the filters were really effective.

Circular Polarizing Filters Test Circular Polarizing Filters Test

Here’s where I expected to put a table showing how efficient the polarizers were. Instead, I’ll just tell you that all of the polarizers we tested blocked all of the light, within our capabilities of measurement. They were all at least 99.9% efficient at doing their job, polarizing light. There’s something you don’t see very often; a photography product that completely does what it says it will do.

Also About the Glass

When we tested UV filters, we found several for which the glass wasn’t flat. We repeated the test on all of the CP filters, and all passed with flying colors, so I won’t bore you with repeating it. Again, my expectation was with two pieces of glass we might see more, not less, bad glass. But no, they all passed just fine. That may be that better glass is used in CP filters, or the polarizing effect evens things out. I don’t know. But they all passed just fine.

What About Light Transmission?

If you’ve ever used a CP filter you are probably aware that even when not polarizing it absorbs some light. You should be aware of this because, well, it’s darker when you look through it. We thought it would be worthwhile to see how much light it does absorb.

Why? Well, partly because we had that laser transmission bench already set up, but mostly because two of these filters claim to let more than 99% of light through. The Marumi claims it lets 99.4% of light through, and the B&W High transmission says it passes through 99.5%.

No, I’m not a rocket scientist, I’m just a regular scientist. But high-tech scientific principles tell me that since everything looks a bit dark when looking through these CP filters, it’s unlikely that more than 99% of the light is passing through the filter. But maybe that’s just me being cynical. Or maybe there are alternative facts that say darker isn’t the same as less light.

Anyway, since I was rather fired up and my BS meter was pegged at full maximum, we removed the linear polarizers and measured absolute transmission for each filter in the non-polarizing position. If you remember, when we tested clear filters the best let 99% of light through, the worst was down around 90%.

The transmission results for CP filters were:


Now, the Marumi and B&W are nowhere close to 99% transmission, but I will admit that they did indeed have higher transmissions than the others.

Some, probably most, people don’t care about how much ND effect their circular polarizer has, and if they do they may well not want the higher transmission variety, they’d prefer a bit more light blocking. After all, if you need a circular polarizer, you probably are shooting where there is lots of bright sunlight. But the takeaway message is that higher transmission filters do tend to give more transmission. Just not as much as is claimed.

Let There Be Spectrometry

And so, in the days after the first article, the people spoke as one and said, “You show us but one wavelength of light, yet there are as many wavelengths as there are fish in the sea. Give us spectrometry, that we may see the effect on all manner of wavelengths, each unto its own kind. And make the graphs brightly colored.” 

It’s taken several weeks for us to get things calibrated and running, but this post seems a good place to start using our new spectrometer. We know that some polarizers give a bit of color cast, especially when polarizing, so we thought it would be interesting to see look at their transmission spectra.

We looked at transmission both in the open and polarizing position and did not see any changes with these polarizers. I’m told there are some that do have a color change with polarizing. I’m only showing you one spectrometry report for each filter, to keep this short post short. Also, don’t put much stock in the absolute transmission between the filters. We weren’t testing for absolute transmission since we’d already done it; we just wanted to look at the curves.

The High-Transmission CPs

The Marumi and B&W filters have similar transmissions and very similar spectra. Both tend to have some UV filtering activity and drop off a little bit at the blue end of the spectrum.


Olaf Optical Testing, 2017


Olaf Optical Testing, 2017

The Standard CPs

These all have a stronger Neutral Density effect than the first two, and their spectra are different, too. The Sigma, Zeiss, and Heliopan filters are all very similar with a bit more transmission at the blue end of the spectrum and a bit less in the red-yellow range. The Tiffen has a similar pattern, although maybe a tiny bit more of a green peak.


Olaf Optical Testing, 2017


Zeiss T*

Olaf Optical Testing, 2017


Heliopan Digital

Olaf Optical Testing, 2017




Olaf Optical Testing, 2017


So What Did We Discover Today?

Well, several things, one of which is really useful. So I’ll get that one out of the way first, and then let this post just steadily deteriorate. If you are buying a circular polarizing filter because you want some circular polarizing, it doesn’t seem to matter much which one you choose; they all polarize like gangbusters. So I saved you some money today.

The second point, one which I’ve been told before I did all this testing, is set the white balance after you put the CP filter on, not before. Because CP filters will have a color cast. Or just shoot in raw and fix it later, which is what we mostly do anyway.

There is a third point, and it’s a painful one:

Once Again, Roger Lets Technology Triumph over Common Sense

I didn’t want to test filters; I really didn’t. But people wanted me to. So I chewed up my testing equipment budget to buy laser transmission stuff and an optical spectrometer, spent a few weeks getting everything calibrated and establishing norms, and then a couple of days testing these CP filters. I did this in clear violation of Roger’s Third Law: No Good Deed Goes Unpunished.

After I was done, I told Aaron I had just documented that CP filters had different light transmission percentages and different color casts. And that high transmission filters had one look, and it was different than regular CP filters, which all were really similar. Because I was proud that my investment in time and money had paid off.

Aaron took the filters from me, put them on a piece of paper, took this picture with his cell phone, and said, “Yeah, you’re right.”



Oh, and BTW – I know what you’re thinking. Yes, I’m going to publish spectrometry reports on the clear and UV filters we tested in the last article. Next week, I promise. I need a few days to recover my pride.

Roger Cicala and Aaron Closz

September, 2017

Addendum: MTF testing

Several people made the very pertinent comment that they would expect some effect in sharpness and contrast. FWIW I took a moderate telephoto, very sharp lens (Batis 135mm f/2.8) and MTF tested it first with no filter, then with a B&W Multi-coated clear filter, then 4 of the CP polarizing filters we tested above.

The clear filter made absolutely no MTF difference.

All tested polarizers (B&W, Marumi, Zeiss, Tiffen Ultra, and Helipan) caused a slight decrease in MTF at high frequencies. There was no detectable change at 10 and 20 lp/mm. At 30 lp/mm there was a consistent 1-2% drop, at 50 lp it was about 4%. All of these CP filters were very similar, I could detect no difference between them.

This is a quick, off-the-cuff check. I’ll look at things in more depth when I have time. But the bottom line is fine detail in photos is affected a bit. I don’t find that the least bit surprising.

I’ve also ordered a couple of $40 filters and we’ll see how those compare.

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 Equipment
  • Eric Bowles

    Hi Roger – I know this is older data, but given the reduced transmission of the violet and blue spectrum, does that suggest that with a high transmission filter the Violet and Blue colors – such as skies – would be darker by a half stop compared to the green and red wavelengths? On the other hand, a standard filter has less falloff in the violet and blue spectrum, so tonal values would be close to the same regardless of color / wavelength.

  • Jimmy T

    Thanks for posting this. You did an excellent job, taking MANY Baby steps for those of us who are among the uninitiated in this mystic science. Bravo!

  • dkphotoman723

    B&H and probably other places that sell filters, have the specs noted. The B+W filters have a 1 to 1 1/2 stop loss of light, which is more on the minimal side of things compared to some other brands. So, not quite sure how the percentage of light transmission translates to stops.

  • otro_mas_2

    I have the Marumi Super Circular Polarising Filter and some days it have a green colour cast that is very annoying. In fact, I have been thinking to buy a B+W filter.

    I think that sharpness and not colour cast are the most important things when using polarising filters.

  • Ashley Pomeroy

    My understanding is that at high altitudes polarising filters are overkill – they make the sky go black instead of dark blue. Perhaps you’re up in the mountains, and the sky is already so dark that tweaking the filter seems to have no effect. I have no idea why it wouldn’t eliminate reflections though.

    I remember trying out some Fuji Velvia a few years ago in the Alps, and the sky was a deep blue even without a filter. Everything looked like a 1990s magazine advert for cars or cigarettes because Velvia was really popular in the 1990s.

  • Roger Cicala

    Ernie, I think the aluminum are a bit temperature dependent. They seem to not like the cold.

  • Ernie Misner

    Thank you for this CP filter test and information Roger. May I please ask an off the wall question? I use CP filters a lot for my outdoor photography and find that my Hoya HD3 and B&W high transmission filters work great and are easy to turn. I can generally leave the lens hood on (rainy NW weather), reach in, and turn the CP filter with one finger. Then I got a Breakthrough Photography “dark” CP filter and to my dismay it was very stiff to turn which required removing the lens hood to turn it. They told me that is because of the titanium material used vs. aluminum in my other CP filters so I guess I am stuck having to remove the hood with their filters. Is that your experience with the aluminum type being much easier to turn? Thank you.

  • Fink

    Based on many years of metrology experience, I’d say the BEST way to get definitive results from a test like this would be to test multiple examples of each filter. Each filter will have a ‘mean’ for all measureables and a standard deviation which is a measure of how much each measure varies from the mean. The idea would be that the highest quality MIGHT be that filter set which exibits the least variation. Or smallest SD.

    Measuring a single sample of anything is really not the best way to determine quality. This applies even MORE to the test I read of UV/Haze filters which had some interesting properties. Again, measuring a larger sample (at least 10) would be more in line. In setting up a control chart for any given process, we’d START with 20 runs……without making any chages. That gave some other measures besides mean and SD.

  • Rudy Leue

    I sent you a note some time back explaining that my polarizing filters (both CP and LP from different manufacturers) don’t work here in northern Peru. They don’t work in the sky and they don’t work to reduce reflections off off things like glass surfaces. Now, I am a relative newby when it comes to photography, starting somewhere in the mid 1960’s, so I don’t know everything but this truly mistifies me.

  • Larry Coleman

    In the version that I know, Churchill was chastised for ending a sentence with a preposition and responded, “That is the kind of pedantry up with which I will not put.”

  • Macro Cosmos

    Pretty nice setup you have there, I see some issues though.
    1. Alignment. It’s annoying, and time consuming right?
    2. Laser type. Yeah just using red could be kind of a problem. Same as green though. Green is actually highly favourable. Try testing the MTF of a lens under green light. You’d be surprised how well it performs.

    My suggestion:
    1. Build a cage system. A 60mm cage system from Thorlabs should do the trick. Saves bucks of buying the CPL filters too, so you can get more than twice the sample size 🙂 Why not stick to the smallest possible filter type? 49mm, some even offer 37mm ones. Too small and unconventional? SCL60C only takes up to 45mm though. The solution is to get an SM2 plate, then SM2>m42, then M42>M52mm.
    2. More LASERS. Can’t have too many lasers!

    I’ll happily accept the retired SCL04 lens mount. I will even cover shipping 🙂 (Please don’t tell him I actually need one but don’t wanna spend $150+ shhhhhhh…)
    Now go buy more testing equipment.

  • Sherwood_Botsford

    Ok, you basically said, ‘they all work’ but really, the cheapest one on your list is still worth major beer.

    Go onto ebay and search for polarizing filters and you get companies like zeikos, zomei, fotga, K&F, Haida, Freewell — It goes on and on, and some *really* cheap. Sure you get what you pay for. Or do you. If you want to continue to entertain, show us how bad it can be…

  • Rudy Leue

    Well, what can I say? I’ve been shooting photography since I was 10, so that 52 years ago and I don’t understand. I remember years ago reading that the f16 rule didn’t work here either. I haven’t tried that one. BTW, when I was in the US, my brother and I rented equipment from you. Always wonderful service. Thank you for that and these interesting articles!

  • Rudy, I absolutely have no clue at all on that one. You’ve stumped me.

  • Rudy Leue

    Wonderful test.
    I have a separate question that relates to polarizing filters that I’ve not seen mentioned anywhere.
    I retired in South America (Peru) after living most of my life in the U.S. and I have successfully used (meaning darkening the sky, removing reflections, saturating colors and making clouds seem like puffs of cotton candy in the sky), polarizing filters from several brands in the U.S. and they do all seem to work. I have at least five different brands here in Peru and with the exception of some reflection removal, none of them work. Why? It doesn’t make a difference which way I am pointing or the time of day, the sky never darkens and the clouds are diffused and washed out.

  • Stephen Feingold

    Another important feature of polarizers is not optical, but the ease of rotation. Polarizers with stiff rotation make it difficult to adjust especially with thin rings and when behind deep lens hoods.

  • Roger Cicala

    oops. fixed that. Thankyou

  • James Thomas

    “…their spectra is different”

    Correct: “…spectra are different”

  • Roger Cicala

    Yes it is. Someone should test that someday. It won’t be me, I test optics.

  • simo

    What about coating and durability ? it’s very important for landscapers who are constantly in contact with water and sand, and landscapers are major users of CPLs.
    I think those 2 factors justify german brands prices

  • I tested three polarizers: AmazonBasics ($13.99), Tiffen ($28.17), and Breakthrough Photography’s X2 ($89). The Amazon filter turned everything brown. Really awful color. The Tiffen looks better than the X2. The polarization is stronger, and the X2 appears to be slightly brownish.

  • Michael Clark

    More than y’all wanted to know about y’all:

    “Here’s how Lewis Grizzard handled the situation: “For some unknown reason, Northerners think Southerners use ‘y’all’ and ‘you all’ in the singular sense. Northerners will giggle and ask, ‘So where are you all from?’ I answer by saying, ‘I all is from Atlanta.'”

  • Michael Clark

    From a diatribe I wrote some time ago:

    “ya’ll” is NEVER singular! “Ya’ll” is ALWAYS plural. Since “ya’ll” is a contraction of “you all”, it is a plural form of the second person singular “you”. Depending on the context it will always include second person and may include third person in the same usage. When only used in the second person it should always be plural, and as such only used when speaking to more than one person. For example, if you are female and have only one sister and I am speaking to both of you and refer to the sisters in your immediate family as “ya’ll”, then “ya’ll” would be second person plural. If you also had a third sister who is not present then it would be both second person plural and third person singular. For “ya’ll” to be used properly when speaking to only one person it MUST also include a third person referent which may be singular or plural. If only you were present but your single hypothetical sister was not, it would be both second person singular & third person singular. The two singular cases combined make it plural. If only you were present and neither of your two hypothetical sisters were, then it would be both second person singular and third person plural. The most common usage is probably when used as both second person plural and third person plural. For example, if I am speaking to you and several other Northern residents and I make a reference to “ya’ll yankees” then “ya’ll” would include all yankees, not just the ones to which I am speaking.

  • Michael Clark

    ‘All y’all’ is redundant, not plural.

  • Michael Clark

    There is no singular form of y’all in true Southern usage! Ever.

    The roots of the word are the Scots-Irish ‘Ya Awe’, which loosely translated is ‘you all’. That might explain why both Hemingway and Faulkner spelled it “ya’ll” when they used it in their writings.

  • Even less likely than not likely. 🙂

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