When is a circular polarizer a circular polarizer

[FrancoD]

Not sure why you seem to find the terms confusing or possibly misleading.

When cameras came out with a metering and or AF system that did not work well with the standard polarizing filters a new ,different, way of polarizing the light came about. To differenciate these new filters from the old ones the term "circular " was added.

From that point on all of the filter manufacturers made both types and all used the same ters , PL and Cir Pl (or the full version and so on..).

Given that Tiffen is a serious reputable brand, why would they stamp Circular Polarizer on one that was not ?

BTW, there has never been a filter that has damaged a camera. You either made the claim you have seen that quote or simply misunderstood what was written.

Or , were you just bored and needed to make another post ?

Does it seem that over time, more people seem to enjoy being mean, putting others down and basically creating a kind of morbid pollution in society. Don't know why that is. I see it more and more, here and in other forums I hang out in.

Why would I make stuff up, or bored and want to make another post, Freud would call this projection. I think you are discussing your internal dark world, not mine.

If your original post was indeed genuine, I apologise for my comment. I'll keep that in mind .

 

[Mr Flip]

I used a Tiffen linear polarizer on a D800 and 28mm lens for ten years. Rarely took it off as I liked the impact on scenes. Sometimes using full polarizing effect, mostly least amount. No negative effects on exposure other reducing the amount of light hitting the sensor which means longer exposures - up to 1.75 stops reduction. No AF issues, though I was using it on a tripod for landscapes only.

I am sorry there is so much misinformation out there. Many “experts” who make things up as they go, manipulating and causing undue fear are about attention and ego.

I liked the better quality Tiffens as they didn’t add additional color cast to an image. Some cheaper Hoyas do.

Circular Polarizers have come a long way with better quality and much thinner glass. In shooting linears vs CPLs, I’ve not noticed any real differences to AF, but again I am not shooting action/moving targets.

Good quality used linears are inexpensive and if you stay with the better names you should obtain fine results.


Good luck.

 

[Mr Flip]

I’ve read linear polarizers don’t play well with the auto focus on digital cameras. But nothing about them doing any damage to them

Linear polarisers do not play well with those dinosaur cameras with the flippy mirrors.

Mirrorless is all OK as they achieve AF via a different way to the flippy mirror types.

Are you saying you have hands on experience? If not then why would you make a statement? Derived from others on the web? Not a good look.

 

[Michael Fryd]

In the photographic world a "circular polarizer" is a linear polarizer sandwiched with a quarter wave plate. Light passed first through the linear polarizer, and then through the 1/4 wave plate. The 1/4 wave plate ensures that the light entering the lens is not linearly polarized.

You can visually tell if a filter is a circular polarizer by looking through it. Look through the filter from the camera side at some reflections on some glass. Turn the filter. You should see the reflections noticeably dim/brighten as you rotate the filter.

Now turn the filter around, and look through it the other way (with the camera side of the filter pointing away from you). Again rotate the filter. If it is a linear polarizer, you will still see the reflections dim/brighten as you rotate. If it is a circular polarizer the reflections will not dim/brighten as you rotate it.

The reason photographers use circular polarizers is that DSLRs use a partial mirror to direct some light to the view finder, and the rest to the metering/autofocus system. If the light hitting the mirror is linearly polarized, it alters the ratio of light that passes through the partial mirror vs. the light that is reflected.

You should use a circular polarizer with a DSLR. Using a linear polarizer with a DSLR won't harm the camera, however the autofocus may not perform properly, and the metering might be off.

You can use either a linear or a circular polarizer with mirrorless cameras, as they don't use partial mirrors.

 

[Mr Flip]

In the photographic world a "circular polarizer" is a linear polarizer sandwiched with a quarter wave plate. Light passed first through the linear polarizer, and then through the 1/4 wave plate. The 1/4 wave plate ensures that the light entering the lens is not linearly polarized.

You can visually tell if a filter is a circular polarizer by looking through it. Look through the filter from the camera side at some reflections on some glass. Turn the filter. You should see the reflections noticeably dim/brighten as you rotate the filter.

Now turn the filter around, and look through it the other way (with the camera side of the filter pointing away from you). Again rotate the filter. If it is a linear polarizer, you will still see the reflections dim/brighten as you rotate. If it is a circular polarizer the reflections will not dim/brighten as you rotate it.

The reason photographers use circular polarizers is that DSLRs use a partial mirror to direct some light to the view finder, and the rest to the metering/autofocus system. If the light hitting the mirror is linearly polarized, it alters the ratio of light that passes through the partial mirror vs. the light that is reflected.

You should use a circular polarizer with a DSLR. Using a linear polarizer with a DSLR won't harm the camera,

however the autofocus may not perform properly, and the metering might be off.

Really? “May not”? First hand experience or quoting another source? Not my experience at all. Please provide your direct experience.

You can use either a linear or a circular polarizer with mirrorless cameras, as they don't use partial mirrors.

 

[Mr Flip]

You know it’s kind of funny this human interaction. Some years ago I was discussing religion with a BIL, and his comment was, being x million followers thereto, they can’t all be wrong (in re: their beliefs). Interestingly, the number of followers was far below those of 3 other religions worldwide and my take away was, the herd mentality and being a party thereto substantiated one’s existence.



One can apply this immediately to followings on the net where presumed most knowledgeable experts have those who absorb and spout the comments of such experts. Ok fine.

I would rather rely upon my own perhaps limited and failure ridden experience than faithfully accept the opinions of the majority, with some exceptions.



Don’t hesitate to take risks, experiment, and find your own reality.



Good luck.

 

[Michael Fryd]

In the photographic world a "circular polarizer" is a linear polarizer sandwiched with a quarter wave plate. Light passed first through the linear polarizer, and then through the 1/4 wave plate. The 1/4 wave plate ensures that the light entering the lens is not linearly polarized.

You can visually tell if a filter is a circular polarizer by looking through it. Look through the filter from the camera side at some reflections on some glass. Turn the filter. You should see the reflections noticeably dim/brighten as you rotate the filter.

Now turn the filter around, and look through it the other way (with the camera side of the filter pointing away from you). Again rotate the filter. If it is a linear polarizer, you will still see the reflections dim/brighten as you rotate. If it is a circular polarizer the reflections will not dim/brighten as you rotate it.

The reason photographers use circular polarizers is that DSLRs use a partial mirror to direct some light to the view finder, and the rest to the metering/autofocus system. If the light hitting the mirror is linearly polarized, it alters the ratio of light that passes through the partial mirror vs. the light that is reflected.

You should use a circular polarizer with a DSLR. Using a linear polarizer with a DSLR won't harm the camera,

however the autofocus may not perform properly, and the metering might be off.

Really? “May not”? First hand experience or quoting another source? Not my experience at all. Please provide your direct experience.

You can use either a linear or a circular polarizer with mirrorless cameras, as they don't use partial mirrors.

According to Canon and Nikon, a circular polarizer will not interfere with autofocus or TTL light metering.

You can see this notice on the listing pages for some of their circular polarizer filters.

This is not to say that Autofocus and metering wont work at all with a linear polarizer. It's just that they might not work. A lot is going to depend on the specifics of the situation.

 

[Michael Fryd]

You know it’s kind of funny this human interaction. Some years ago I was discussing religion with a BIL, and his comment was, being x million followers thereto, they can’t all be wrong (in re: their beliefs). Interestingly, the number of followers was far below those of 3 other religions worldwide and my take away was, the herd mentality and being a party thereto substantiated one’s existence.

One can apply this immediately to followings on the net where presumed most knowledgeable experts have those who absorb and spout the comments of such experts. Ok fine.

I would rather rely upon my own perhaps limited and failure ridden experience than faithfully accept the opinions of the majority, with some exceptions.

Don’t hesitate to take risks, experiment, and find your own reality.

Good luck.

Nothing wrong with doing your own experiments. That's a good way to verify how your gear performs in your circumstances.

Just be wary of extrapolating that to other situations or other combinations of gear.

 

[FrancoD]

I had a look at the same info from Canon and Nion.

In particulkar , from Canon :

Simple to use, these filters polarize light circularly, rather than linearly, so they do not interfere with autofocus or TTL light metering.

it's pretty clear to me that they imply that linear filters can or do interfere with AF and or TTL light metering.

 

[JimH123]

My round screw in Tiffen circular polarizers have the words "Circular Polarizer" printed on the edge. My linear polarizers just have "Polarizer" written on the edge ( along with "Warm" or "Low Light", etc if it is one of those specialty linear polarizers)

Other brands have similar markings. For example my Hoya circular polarizers have "PL-CIR" printed on the edge of the ring.

Linear polarizers won't damage the camera. They do not work well with ma,y autofocus and metering systems however.

Thanks for the reply, I am guessing you are correct.

Linear polarizers may work with mirroless cameras fine. But I'm not 100% sure if they work will all.

By the way, it may be time for you to see an ophthalmologist: "If cameras and lenses can have autofocus then why can't I?"

Referring the mental focus here

There is no problem using linear polarizers on mirrorless camera. They focus on the sensor and are not affected by differences between circular and linear polarizers.

In the case of a DSLR, the alternate light path to the focusing and metering via the flip up mirror "May" be fooled and produce inaccurate results. Note the use of the word "May". It is not a given that it will produce inaccurate results. But that it "May" produce inaccurate results.

A linear polarizers on a mirrorless may actually produce slightly better detail since there is no quarter wave plate disturbance to interfere with the light.

I have linear polarizers from my film days and they work fine on my mirrorless cameras.

 

[ThrillaMozilla]

A linear polarizers on a mirrorless may actually produce slightly better detail since there is no quarter wave plate disturbance to interfere with the light.

A quarter wave plate produces circularly polarized light. How exactly do you think that will produce a disturbance to interfere with the light?

 

[Svein Eriksen]

.....

So is my Tiffen filter a circular or linear?

If it says circular on the filter then I assume it's circular. Circular polarizers are nothing new. I bought my first in the mid-seventies and it was a B+W circular polarizer. 72mm and horribly expensive at the time but required for correct metering with Canon FTb.

 

[JimH123]

A linear polarizers on a mirrorless may actually produce slightly better detail since there is no quarter wave plate disturbance to interfere with the light.

A quarter wave plate produces circularly polarized light. How exactly do you think that will produce a disturbance to interfere with the light?

It's just one more thing for the light to pass though.

 

[tbcass]

I know you are not suppose to use a linear polarizer on a digital camera so I am reluctant to just slap this filter on a lens and test it out, one source suggested it could damage my camera's internals.

While I can't answer your question the idea that using a linear polarizer on a digital camera could damage it is something I cannot believe and defies all logic. It sounds like another example of the tons of misinformation you find on the web.

--
Tom

 

[ThrillaMozilla]

A linear polarizers on a mirrorless may actually produce slightly better detail since there is no quarter wave plate disturbance to interfere with the light.

A quarter wave plate produces circularly polarized light. How exactly do you think that will produce a disturbance to interfere with the light?

It's just one more thing for the light to pass though.

You mean like a piece of glass. OK, I see what you're saying, but most likely it's a thin film, similar to the polarizers. While filters are not optically perfect, I don't know of any comparison of the quality linear and circular polarizers. It's not something I personally would worry about.

On the other hand, a linear filter may interfere with the birefringent optical low-pass filter that is present on many camera sensors. I haven't seen it demonstrated, but the birefringent filters work by beam splitting . In the wrong orientation a linear filter would eliminate one of the images and therefore interfere with the low-pass filter.

 

[Mark B.]

Okay, I do know there are linear and circular polarizers. Here is my problem. While rummaging through some of my camera bags I found a polarizer I forgot I owned. What it says on the filter is "Tiffen circular polarizer.

Now logic would have me believe it is a circular polarizer and not just the shape of the filter which is round. My problem is that over the years, first SLR in 1974, I have bought a few polarizers. I know you are not suppose to use a linear polarizer on a digital camera so I am reluctant to just slap this filter on a lens and test it out, one source suggested it could damage my camera's internals.

But I might have bought this filter when I purchased my first digital camera in 2004 (the Original Digital Rebel camera with a whooping 6.2 megapixels). In this case the word circular would mean circular in the technical sense and not the shape sense.

I am often amazed when I go into Facebook marketplace and see a picture of a bike with the caption "bike" under it. Maybe it is because I am incredibly intelligent that I am able to look at the picture of the bike and realize it is a bike. But I guess the author of this ad felt there were many stupid people out there who needed to know it is a bike.

Maybe Tiffen felt that the round shaped polarizer need to be labelled "circular" to let the stupid folks know the shape of the filter.

So is my Tiffen filter a circular or linear?

Ummm, "circular" has absolutely nothing to do with the fact that it is a round filter. It has to do with how the polarization is done. Polarizing filters are therefore labeled as "circular" or "linear". So yes, the Tiffen filter you have is in fact a circular polarizer.

Rather than try to explain the difference, here's an article about linear vs circular polarizers:

https://ehabphotography.com/linear-vs-circular-polarizing-filter-why-do-i-need-one/

 

[Joseph S Wisniewski]

Okay, I do know there are linear and circular polarizers. Here is my problem. While rummaging through some of my camera bags I found a polarizer I forgot I owned. What it says on the filter is "Tiffen circular polarizer.

Now logic would have me believe it is a circular polarizer and not just the shape of the filter which is round. My problem is that over the years, first SLR in 1974, I have bought a few polarizers. I know you are not suppose to use a linear polarizer on a digital camera so I am reluctant to just slap this filter on a lens and test it out, one source suggested it could damage my camera's internals.

Well, the damage myth has been covered.

It wasn't just DSLRs. A lot of FSLRs wanted circular polarizers. I had an early one, a Nikon FA I got around 1985. It needed circular polarizers or you'd have metering errors.

But I might have bought this filter when I purchased my first digital camera in 2004 (the Original Digital Rebel camera with a whooping 6.2 megapixels). In this case the word circular would mean circular in the technical sense and not the shape sense.

Circular polarizer always means in the technical sense, not the shape sense.

I am often amazed when I go into Facebook marketplace and see a picture of a bike with the caption "bike" under it. Maybe it is because I am incredibly intelligent that I am able to look at the picture of the bike and realize it is a bike. But I guess the author of this ad felt there were many stupid people out there who needed to know it is a bike.

Maybe Tiffen felt that the round shaped polarizer need to be labelled "circular" to let the stupid folks know the shape of the filter.

So is my Tiffen filter a circular or linear?

Probably linear. Again, not about the shape, but about the physics.

Like you said, old polarizer that you found in a camera bag, at least 20 years old and possibly much older.

Tiffen circular polarizers were notorious for failures. Circular polarizers have a conventional linear polarizer and a "1/4 wave delay plate" that transforms linear polarization into circular polarization. I don't know where Tiffen sourced those 1/4 wave plates, but I had two of them fail. First it would delay less than 1/4 wave, causing the polarizer to color your sky randomly yellow or cyan as you rotated the polarizer. Then it would fail outright and the polarizer became a pure linear polarizer.

(Oh, and if you're looking for more info on this, it's not actually called a "1/4 wave delay plate", I had to use "delay" to replace a scientific term for that dpReview thinks is a "bad word").

I had two old Tiffens fail. I also had an expensive Heloppan IR blocking filter fail. That's about it for filter failures. That's how those two companies because people I'll never deal with again.

 

[TechTalk2]

Okay, I do know there are linear and circular polarizers. Here is my problem. While rummaging through some of my camera bags I found a polarizer I forgot I owned. What it says on the filter is "Tiffen circular polarizer.

Now logic would have me believe it is a circular polarizer and not just the shape of the filter which is round. My problem is that over the years, first SLR in 1974, I have bought a few polarizers. I know you are not suppose to use a linear polarizer on a digital camera so I am reluctant to just slap this filter on a lens and test it out, one source suggested it could damage my camera's internals...

...So is my Tiffen filter a circular or linear?

Your Tiffen Circular Polarizing Filter, as has already been pointed out, polarizes the light thru a linear polarizing sheet and then produces a circular wave pattern by passing the linear polarized light through a quarter-wave plate which make it a circular polarizer and not a linear type. These are recommended for a variety of both film and digital camera types.

Circular polarizers will work with any type of camera design. They do not negatively affect camera exposure or autofocus functions. Circular polarizers became common for still camera use when autofocus SLR film cameras appeared in the 1980s with beamsplitters to relay light to sensors located in the base of the camera.

There are a variety of different types of beamsplitters, including polarizing and non-polarizing types among other distinctions. Linear polarizers when combined with the beam splitting components in many later model SLR and DSLR cameras may interact in a way that affects the intensity of light which autofocus or TTL metering sensors require to operate consistently and reliably and are not recommended.

In other types of cameras which do not have beam splitters in the light path, a linear polarizer (see pages 12, 13, and 27 for a few examples of items discussed above and some of their potential applications) works without interference in any camera features and may be used as desired. For example, most mirrorless or older manual focus SLR film cameras would work equally well with either a linear or circular polarizer.

The article linked below from the American Society of Cinematographers provides a good basic overview. The links above will provide additional details and depth for those interested.

https://theasc.com/blog/shot-craft/understanding-polarizing-filters

 

[jxh]

I have never used a linear polarizer, but this post at Stackexhange has some suggested ways of distinguishing between the different polarizer types:

https://physics.stackexchange.com/q...ether-i-have-a-circular-or-a-linear-polarizer

I.e., if linearly polarized light of various wavelengths enters the quarter-wave plate, it will emerge from it with various degrees of elliptical polarization (essentially a mix of linear+circular polarizations) from it, dependent on its wavelength.

...
Then the simple linear polarizer will work exactly the same, but the circular one will work different; it should show less dimming/brightening when rotated and possibly some color variations to the light when flipped."

Looks like a good explanation, and the fact that they produce a less drastic effect is probably is the reason why currently polarizers are not commonly used

 

[jxh]

I'm not sure how this would be possible. Ultimately they just block some of the incoming light depending on its polarization.

That's what I thought but I don't want to find out the hard way the guy was right.... lol.

Considering that blue sky and reflections off non metallic surfaces (glass, water) are inherently polarized would suggest this is not a risk.