Circular vs Linear Polarizer on m4/3 Camera

Charley123 wrote:

I know (or think I know) that a mirrorless camera can use either type of polarizer. Is that correct?

Yes.

Is it the linear or circular that is rotated to polarize? I don't recall.

Both do.

Which would do a better job for image quality on a mirrorless camera?

It shouldn't matter as long as they are good quality filters.

Could I rotate a polarizer on a lens that has a bayonet mount lens hood?

Yes - if it has a filter thread as well. Depending on the lens, you may have to remove the hood to use the polariser but you could buy a third party hood to screw into the front of the filter.

Cheers

Brian

JDLaing wrote:

Circular polarizers rotate to increase or decrease polarization.

So do linear polarizers. In this respect there is no difference. You can use either type on a mirrorless camera. There is no particular reason to prefer one over another, although good quality linear polarizers do seem harder to find these days.

I have a Marumi circular polarizer and an old Hoya linear polarizer. Both rotate to adjust degree of polarization and both work fine on m43 cameras. The only difference I have noticed is that the Hoya seems to have a stronger polarizing effect.

jpig wrote:

JDLaing wrote:

Circular polarizers rotate to increase or decrease polarization.

So do linear polarizers. In this respect there is no difference. You can use either type on a mirrorless camera. There is no particular reason to prefer one over another, although good quality linear polarizers do seem harder to find these days.

I have a Marumi circular polarizer and an old Hoya linear polarizer. Both rotate to adjust degree of polarization and both work fine on m43 cameras. The only difference I have noticed is that the Hoya seems to have a stronger polarizing effect.

I have never seen a coated, much less multicoated linear pola, so end up using circular for my OM-Ds despite the extra cost and greater light loss. Circular are only required where there is a beam splitting scheme, as done with DSLRs.

For folks who don't know, all screw-on pola filters rotate, which is different than "circular" technology: "...comprises firstly a linear polarizer which performs the artistic function just described, followed by a quarter-wave plate which further transforms the now-linearly polarized light into circularly-polarised light before entering the camera. This additional step avoids problems with auto-focus and light-metering sensors within some cameras, which otherwise may not function reliably with a simple linear polariser."--Wiki

Cheers,

Rick

PDAF requires CPL.  CDAF works with both.

hutu wrote:

PDAF requires CPL. CDAF works with both.

Good point All of us with EM1's need CPL as we have both PDAF and CDAF, on this basis the answer that Mirrorless can use either is incorrect. Or  does it make no difference to an on sensor PDAF, I would have thought not but maybe there is an expert out there who can confirm or deny this so we can be exact ?

jpig wrote:

JDLaing wrote:

Circular polarizers rotate to increase or decrease polarization.

So do linear polarizers. In this respect there is no difference. You can use either type on a mirrorless camera. There is no particular reason to prefer one over another, although good quality linear polarizers do seem harder to find these days.

I have a Marumi circular polarizer and an old Hoya linear polarizer. Both rotate to adjust degree of polarization and both work fine on m43 cameras. The only difference I have noticed is that the Hoya seems to have a stronger polarizing effect.

Yes, linear polarizer has a stronger polarizing effect. I used to know that. Eventually forgot it. Memory refreshed now.

drj3 wrote:

olyham wrote:

hutu wrote:

PDAF requires CPL. CDAF works with both.

Good point All of us with EM1's need CPL as we have both PDAF and CDAF, on this basis the answer that Mirrorless can use either is incorrect. Or does it make no difference to an on sensor PDAF, I would have thought not but maybe there is an expert out there who can confirm or deny this so we can be exact ?

I thought the reason for circular polarizers for SLRs/DSLRs was the use of beam splitters and not fully reflective mirrors. Since the E-M1 does not have either, why would it need a circular polarizer?

It is probably not relevant (even though you would have less light loss with a linear polarizer), since I have not seen a high quality multicoated linear polarizer.

Heliopan makes high quality double coated linear polarizers. Hoya makes good linear polarizers, but they're uncoated. Add a lens hood and you're good to go.

drj3 wrote:

olyham wrote:

hutu wrote:

PDAF requires CPL. CDAF works with both.

Good point All of us with EM1's need CPL as we have both PDAF and CDAF, on this basis the answer that Mirrorless can use either is incorrect. Or does it make no difference to an on sensor PDAF, I would have thought not but maybe there is an expert out there who can confirm or deny this so we can be exact ?

I thought the reason for circular polarizers for SLRs/DSLRs was the use of beam splitters and not fully reflective mirrors. Since the E-M1 does not have either, why would it need a circular polarizer?

It is probably not relevant (even though you would have less light loss with a linear polarizer), since I have not seen a high quality multicoated linear polarizer.

I get very poor  AF results when using a CPL on the EM1 in C-AF high speed sequential, I guess there could be a few factors causing that, but needless to say I never use it when operating in that mode, I have also never used an LPL in that same config. to test if it is related as I only have a smaller LPL.

hutu wrote:

PDAF requires CPL. CDAF works with both.

Are you sure about that? I don't know that on-sensor PDAF is affected, while beam-split AF and metering are.

Cheers,

Rick

Linear polarizers are a bit more effective than circular polarizers. Considering that polarizer-happy photogs often overdo the effect, it is not a bad thing to use a circular polarizer by default. It will work on any camera.

The highest quality polarizers are environmentally sealed, which prevents the sandwiched polarizer foil from getting damaged due to moisture. These pricey filters are called Käsemann.

Some cameras require circular polarizers for the AF system to work proplery. The manual should say, or you can call technical support.

For use with wide-angle lenses, get slim polarizers. The ones with a thick mount may cause vignetting.

Here is what I've learned, what I bought, and why I bought it.

I bought a linear polarizer because it will work with my mirrorless, contrast detection M10ii and M5ii. Linear will work better than circular because linear polarizes more strongly. Normally linear costs way less than circular, but not in this case since I bought Heliopan linear which costs as much as a good Hoya circular.

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The only brands of linear polarizers I could find are made by Heliopan, Tiffen, and Hoya.

Hoya doesn't make size 37mm linear polarizer, or at least none available in that size.

Hoya and Tiffen linear polarizers are uncoated.

Heliopan was the only brand I could find for a 37mm multi-coated linear polarizer.

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I bought Heliopan linear (multi-coated) polarizer in size 37mm and 46mm for $69 each from BHPhoto.

Heliopan was the only brand of linear polarizer (that I could find) with anti-reflective lens coating on each side.

Heliopan linear polarizer is rated 5 stars by users at BHPhoto.

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The other good, high-end, linear polarizer I found was Hoya for $22 each. It does not have any lens coatings, but is rated 5 stars by users at BHPhoto. I've had excellent results from Hoya in the past and would have bought it, but it didn't have any lens coatings. I'm sure it's the best linear polarizer for the money, but it's not available in size 37mm, which is another reason I didn't buy Hoya.

The lack of lens coatings didn't matter much back in my film days when I got excellent results from Hoya and Tiffen uncoated linear polarizers. However, I'm not sure if that same applies to digital. Would the lack of lens coatings be a problem for digital? I don't know, which is why I went for the coated Heliopan at way more cost.

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Tiffen linear polarizer was available for $19, but has no lens coatings. It's rated 4 stars by BHPhoto customers. I didn't buy it because I think the Hoya and Heliopan are better. However, in my college days (using film) I used a Tiffen polarizer and it gave excellent results. It was great with film. It's probably good with digital too. But I can afford better now. Hoya is better for only $2 more. Heliopan is much better for $50 more.

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Though my question stands... Does lens coating (or lack of) on a linear polarizer matter more for digital than for film? Cause on film I was getting great results with cheap uncoated linear polarizers like Tiffen and Hoya.

You are a better sleuth than I, who has never found a coated LP when I've looked. Please post some shots once you get dialed in!

Cheers,

Rick

p.s. I don't believe coating will affect the pola effect, just increase light transmission, and reduce flare when bright light hits the filter.