Circular and linear polarizers not the same after all?

[bagdad child]

I am looking to get a 105mm polarizer for the screw in adapter ring for the Lee system. I have the linear Heliopan in mind, which is a fair bit cheaper than the circular version. I have used both linear and circular polarizers and I am aware of their differences when it comes to split-beam metering, quarter wave plate etc. Recently, however, I have come across some accounts claiming that linear polarizers are more efficient in eliminating reflections while circular polarizers would cause or enable stronger color saturation than linear ones and therefore a circular polarizer may prove more beneficial than a linear one for critical color work regardless of the camera's metering system or lack thereof. Someone goes on to say that it's written in Heliopan owner's manuals that their circular and linear polarizing filters differ in the aforementioned way, whereas B+W supposedly claims that their linear and circular polarizing filters produce identical outcome on film. This is all news to me. I do work mostly with color and do not like the idea of the linear polarizer being less punchy than the circular one. It will be much appreciated if anyone can help me out on this. Many thanks.

[BarryS]

I've got both types and strongly recommend getting a linear polarizer, unless you really need to spend the extra money on the circular for a known requirement. I've found that some of the autofocus/metering systems that supposedly don't work correctly with linear polarizers are just fine with them and I've never noticed a significant difference in saturation.

[aduncanson]

I have little experience with circular polarizers for photographic use. That said, I would speculate that this is a case of a marketeer who understood little other than that the circular polarizer costs more, attributing more of the usual positive polarizer characteristics to the more expensive circular version.

My foggy recollection is that a circular polarizer is first a linear polarizer with a quarter wave plate following it. I am willing to bet that the quarter wave plate induces a delay (in one polarization plane relative to the perpendicular one) that is not exactly a quarter wave across all wave lengths. If I am right, then the circular polarizer will be to some degree eliptical for all but one wavelength. It is difficult to imagine how the quarter wave plate and its imperfections could improve the polarizer's performance.

I would recommend saving the extra cost of the circular polarizer and buy instead the best linear one you can find.

[Peter K]

A circular polarizer is only needed if one uses an interior light measuring system used in SLR-cameras to avoid depolarizing by prisms and mirrors inside the camera. So a circular polarizer should be choosen if the same filter has to be used with LF- and SLR-cameras. For LF-cameras only there is no difference at all except the price.

[Alan Davenport]

The first thing to keep in mind, is that both linear and circular polarizers have exactly the same effect on the film.

The second thing to consider, is whether you now own any other cameras that require a circular polarizer.

The most important thing to consider, IMO, is whether there is any possible chance that you may decide to purchase such a camera at any time in the future. If there's a snowball's chance in hell that you'll ever own a camera that requires circular polarizers, you might as well bite the bullet and buy one now; it'll just cost more in a few years. In the meantime it will work just fine on everything else you own. Circular polarizers work on ALL cameras.

[Peter De Smidt]

The consensus of the pros where I work is that linear polarizers are more effective than circular ones.

[bagdad child]

Thank you all of you for your replies.


The consensus of the pros where I work is that linear polarizers are more effective than circular ones.

Peter, in what way do the pros consider the linear polarizers being more effective? I have heard from different sources that they for instance should reduce reflections on a water surface more effectively than circular polarizers, but again, I have not seen this with my own eyes.

[Peter K]

If the polarizer comes before the lambda/4 foil also a circular polarizer removes reflexions on non-metalic surfaces like water, if the surface reflects the incident light coming from an angle of 30° to 40° depend on the surface material. But the polarizing foil and specialy the lambda/4 foil can only be made for a certain wave band. So not all wave-lenghts are cut-out and turned in circular waves. But in photography this isn't important.

[Brian Ellis]

I'm not sure I'd use any polarizer for "critical" color work, at least not without first testing it. Joe Englander wrote an interesting article in the final issue of "Camera and Darkroom" magazine many years ago, showing the results of his tests of different brands of polarizers. Each different brand produced a slight but noticeable difference in the color cast. I don't remember whether he compared linear and circular of the same brand or not but there was a definite difference among brands.

[bagdad child]

I'm not sure I'd use any polarizer for "critical" color work, at least not without first testing it. Joe Englander wrote an interesting article in the final issue of "Camera and Darkroom" magazine many years ago, showing the results of his tests of different brands of polarizers. Each different brand produced a slight but noticeable difference in the color cast. I don't remember whether he compared linear and circular of the same brand or not but there was a definite difference among brands.

Thank you Brian!

I googled the Englander article and the results are in fact found on largeformatphotography.info!

Below are the results of Englander's test. Highly interesting!

http://www.largeformatphotography.info/filters.html

Many polarizers tend to have a cold color bias. It's generally better to have a warm color bias than a cold color bias, hence the interest of the warm tone polarizers. In a C&D article, Englander compared ten linear and circular polarizers. His densitometer readings are (total,red,green,blue):

Wratten (.6,.62,.62,.62)
B+W Warm (.56,.57,.57,.58)
B+W circular (.51,.55,.52,.48)
Heliopan circular (.58,.64,.58,.53)
Heliopan linear (.62,.69,.63,.57)
Heliopan Warm (.60,.60,.61,.56)
Tiffen linear (.50,.52,.49,.50)
Tiffen circular (.51,.50,.52,.47)
Hoya circular (.54,.56,.55,.53)
Hoya linear (.45,.47,.45,.43).
Tiffen Warm (.62,.58,.62,.62)

He concluded that the most neutral filter was the B+W Warm. The Tiffen Warm is linear. Hoya has subsequently introduced a Warm polarizer (called the Moose filter, after the so-named wildlife photographer) in circular version, which is relatively economical.

Englender also found the Wratten .6ND filter to match the density of the polarizers well. This confirms the rule to use a filter factor of two stops for a polarizer.

[Brian Ellis]

This Forum certainly is an amazing resource, I didn't realize the Englander article was here. The original article included the photographs Englander had made with each polarizer so that you could see the actual differences (to the extent the magazine was able to duplicate the originals).

[walter23]

The filtering effect is basically the same - a circular polarizer *is* a linear polarizer, it just happens to have the quarter wave plate you mention to sort of "depolarize" the light that comes out the rear end of the polarized filter.

The only difference I've noticed is that my circular polarizer gives a more noticable color cast (sort of muddy green-grey) than the linear one I have.

Other than those kinds of issues (which probably are as much a matter of brand and quality as anything to do with whether or not it's LP or CP), they should function identically.


I am looking to get a 105mm polarizer for the screw in adapter ring for the Lee system. I have the linear Heliopan in mind, which is a fair bit cheaper than the circular version. I have used both linear and circular polarizers and I am aware of their differences when it comes to split-beam metering, quarter wave plate etc. Recently, however, I have come across some accounts claiming that linear polarizers are more efficient in eliminating reflections while circular polarizers would cause or enable stronger color saturation than linear ones and therefore a circular polarizer may prove more beneficial than a linear one for critical color work regardless of the camera's metering system or lack thereof. Someone goes on to say that it's written in Heliopan owner's manuals that their circular and linear polarizing filters differ in the aforementioned way, whereas B+W supposedly claims that their linear and circular polarizing filters produce identical outcome on film. This is all news to me. I do work mostly with color and do not like the idea of the linear polarizer being less punchy than the circular one. It will be much appreciated if anyone can help me out on this. Many thanks.

[walter23]

A circular polarizer is only needed if one uses an interior light measuring system used in SLR-cameras to avoid depolarizing by prisms and mirrors inside the camera. So a circular polarizer should be choosen if the same filter has to be used with LF- and SLR-cameras. For LF-cameras only there is no difference at all except the price.


Incidentally I've never had a problem using a linear polarizer on my Canon digital autofocus camera (350D / digital rebel XT), nor my autofocus film body (Canon Elan 7n). Metering and AF both work perfectly fine.

Maybe the problem was historical, with some of the first AF bodies, or maybe it's a Nikon / Pentax / olympus thing?

[walter23]

I'm not sure I'd use any polarizer for "critical" color work, at least not without first testing it. Joe Englander wrote an interesting article in the final issue of "Camera and Darkroom" magazine many years ago, showing the results of his tests of different brands of polarizers. Each different brand produced a slight but noticeable difference in the color cast. I don't remember whether he compared linear and circular of the same brand or not but there was a definite difference among brands.

Yeah, that's definitely the major issue here. You may find a colour cast when switching from LP to CP from the same brand, or between various LPs or CPs between brands.

[Daniel_Buck]

after doing some work with polarizing filters/gels shooting textures (a combination of large gels on lights, and circular filter on the camera) I've come to believe that their effect is the same, or at least no noticeable difference when I swapped out the circular filter on the lens for another gel. at least I didn't notice any difference for what I was doing. There was possibly a slight difference in color, but it was very minor.

[bagdad child]

Here is the full Englander article!

http://www.joe-englander.com/documents/polarizer.pdf

The results are somewhat mind-boggling...

You may want to think twice before you splash out $200 or $300 for a polarizer. What color cast will it give to your images? The linear Heliopan does not give the same color as the circular Heliopan... hmmm... And the Kaesemann models are for optimum sharpness..?!

[Peter K]

What color cast will it give to your images? The linear Heliopan does not give the same color as the circular Heliopan... hmmm... And the Kaesemann models are for optimum sharpness..?!
But in practice the difference are just marginal, except you take pictures on the same roll with all this different filters from the same scene.

[bagdad child]

But in practice the difference are just marginal, except you take pictures on the same roll with all this different filters from the same scene.

Peter,
I have not tested different polarizers on the same lens in the same scene and conditions and I prefer not to do so as well. Therefore it would be helpful if the manufacturers of the filters would reveal the true data on their filters. The differences between different polarizers in practice may be marginal for some applications while important for others. The Englander test certainly suggests that the differences are not insignificant.

[Peter K]

What do you want, datas or pictures? The differences between different polarizers in practice is marginal, if the filter is flat and clean. All this tests have only one reason: to feel insecure about irrelevant differences. I've many polarizers from different manufacturers. The only important thing is the thread and in the case of a SLR if it's a circular polarizer. So don't worry and take pictures.

[C. D. Keth]

I have a little bit of new perspective to add to this discussion. In my day job, I'm a camera assistant for TV and feature films. I have never once seen a director of photography agonize a tenth of what you guys have in this thread over which POLA he is going to use. If the guy with millions of dollars of budget money entrusted to his photography doesn't care, it's probably not a big enough deal to worry about.

As for color cast, who is printing their color work without final color tweaking in printing, anyway? Nobody? That's what I thought.

[bagdad child]

I have a little bit of new perspective to add to this discussion. In my day job, I'm a camera assistant for TV and feature films. I have never once seen a director of photography agonize a tenth of what you guys have in this thread over which POLA he is going to use. If the guy with millions of dollars of budget money entrusted to his photography doesn't care, it's probably not a big enough deal to worry about.

those who have millions of dollars generally do not worry much. they can readily throw away a $$$ polarizing filter they do not like and pick another one from the pile.

[C. D. Keth]

those who have millions of dollars generally do not worry much. they can readily throw away a $$$ polarizing filter they do not like and pick another one from the pile.

You entirely missed my point. Besides, the director of photography doesn't have the money. He is, however, expected to produce a product worthy of the budget. What I mean is that when you are expected to produce perfection on a movie, you take every tiny detail as a giant decision. I have never had a DP refuse whatever POLA I got him at the rental house so it's not THAT big a decision.

[Alan Davenport]

I have never had a DP refuse whatever POLA I got him at the rental house so it's not THAT big a decision.

I'm not sure the use of real-world examples is ever relevant to the discussions that go on around here. Kinda takes the fun out of it, you know...