Circular Polarizer vs Polarized Sunglasses

Hi,

Perhaps someone can clarify something that has vexed me for some time already. As we all know circular polarizers for our lenses only show the intended effect when at a 90 degree angle to the sun direction. But polarized sunglasses appear to not, or at least much less, require that and yield a view with enhanced contrast even when the sun is directly behind you. Why is that? And why can't such polarizers be made for lenses?

Thanks. Joerg

The reason you can't use a linear polarizer on most modern cameras is because it messes up the AF and the metering. Here is an article on the Singh-Ray site I wrote that dives into some detail on how polarizers work and the differences between linear and circular polarizers:
https://singh-ray.com/equipment-techniq ... -work-use/

E.J. Peiker wrote:The reason you can't use a linear polarizer on most modern cameras is because it messes up the AF and the metering.  Here is an article on the Singh-Ray site I wrote that dives into some detail on how polarizers work and the differences between linear and circular polarizers:
https://singh-ray.com/equipment-techniq ... -work-use/

Thanks E.J.! Nice article. If linear polarizers are not compatible with beam splitters shouldn't they work with mirrorless cameras then? At least, the AF is on sensor but I am not sure how they do the metering...

Joerg

Joerg Rockenberger wrote:

E.J. Peiker wrote:The reason you can't use a linear polarizer on most modern cameras is because it messes up the AF and the metering.  Here is an article on the Singh-Ray site I wrote that dives into some detail on how polarizers work and the differences between linear and circular polarizers:
https://singh-ray.com/equipment-techniq ... -work-use/

Thanks E.J.! Nice article. If linear polarizers are not compatible with beam splitters shouldn't they work with mirrorless cameras then? At least, the AF is on sensor but I am not sure how they do the metering...

Joerg

There are some mirrorless cameras that work with linear polarizers but i don't have a listing of those that do and those that don't.

Do you happen to know if the Sony a7 mIII works with linear polarizers? And do you have a recommendation for a good quality linear polarizer?

Thanks. Joerg

Joerg Rockenberger wrote:Do you happen to know if the Sony a7 mIII works with linear polarizers? And do you have a recommendation for a good quality linear polarizer?

Thanks. Joerg

Well your post got me to digging through an ancient box of filters from the 1970's and I found a cheap old 72mm linear polarizer.  I also found a 77 to 72mm step-down ring which allowed me to mount it on the Sony 100-400 and the a7R III.  It seems to work just fine especially since I don't really use the exposure meter on mirrorless cameras but rather rely on the in viewfinder aids such as peaking and pre-exposure blinkies but the meter also appears to work fine.

As for brand, I would look for something that is multi-coated from one of the reputable manufacturers.

A circular polarizer as I understand it is a linear polarizes with a 1/4 wave plate which essentially"depolarizes" the light coming out of the linear polarizer after it has eliminated the undesired light so that when it hits the camera sensors they are not effected. Assuming that the sunglasses polarizer and the linear polarizer in the circular polarizer are oriented the same, the visual effect should be the same.

My guess is how the polarization filter is oriented in your glasses is causing the phenomenon you describe. A polarizer is needs to be oriented perpendicular to the oriention of the polarization of reflected light for maximum effect. My guess is that sunglass polarizers are fixed oriented to eliminate reflections (polarized light) off of horizontal surfaces such as water, rather than sky for example which we get by orienting the camera filter for a particular situation.The variations I think are probably generated by the differences between orientations of the two polarizers. Just a guess

This is an interesting topic. Reminded me of years ago when I played with polarised film on on my off-shoe flash combined with a circular polarised filter on my macro lens. Fascinating exercise, but the results weren't really worth the effort, as I recall.

Tom Robbins wrote:This is an interesting topic. Reminded me of years ago when I played with polarised film on on my off-shoe flash combined with a circular polarised filter on my macro lens. Fascinating exercise, but the results weren't really worth the effort, as I recall.

Ah yes, cross polarization but for that to really work well, you have to use linear polarizers on both he flash heads and the lens.  In macro you generally don't use AF so it isn't much of a problem even on a DSLR.

E.J. Peiker wrote:

Joerg Rockenberger wrote:Do you happen to know if the Sony a7 mIII works with linear polarizers? And do you have a recommendation for a good quality linear polarizer?

Thanks. Joerg

Well your post got me to digging through an ancient box of filters from the 1970's and I found a cheap old 72mm linear polarizer.  I also found a 77 to 72mm step-down ring which allowed me to mount it on the Sony 100-400 and the a7R III.  It seems to work just fine especially since I don't really use the exposure meter on mirrorless cameras but rather rely on the in viewfinder aids such as peaking and pre-exposure blinkies but the meter also appears to work fine.

As for brand, I would look for something that is multi-coated from one of the reputable manufacturers.

Hi E.J., thanks for the follow up. That sounds encouraging. Hopefully, my images in the future will look more like what I saw through sunglasses.

As for leading manufacturers, I presume that includes Hoya, Sing-Rayh and B&W, right?

Thanks. Joerg

... and Heliopan, Breakthrough, Zeiss, Sigma, Nisi, Formatt-Hitech, etc, etc, etc

E.J. Peiker wrote:... and Heliopan, Breakthrough, Zeiss, Sigma, Nisi, Formatt-Hitech, etc, etc, etc

Thanks.

Now that's weird! I am looking at the Hoya 77 mm linear polarizer B-77PL-GB on B&H and it states that the strongest effect is at an 90 degree angle from the sun. What gives?

Joerg

That's the case for all polarizers regardless of whether they are circular or linear.  Wildflower-nut describes what you are seeing with your sun glasses above.

Both types have a linear polarizing element as the first point of entry to the light so they will behave the same way.  The difference is what is done to that light after it has entered the front facing linear portion of the polarizer.

E.J. Peiker wrote:That's the case for all polarizers regardless of whether they are circular or linear.  Wildflower-nut describes what you are seeing with your sun glasses above.

Both types have a linear polarizing element as the first point of entry to the light so they will behave the same way.  The difference is what is done to that light after it has entered the front facing linear portion of the polarizer.

Thanks. But I don't get it why polarized lenses in sunglasses don't show this orientation effect. I thought the different behavior is due to the use of linear polarizers. But that's obviously wrong.

Best.

Joerg Rockenberger wrote: ......Thanks. But I don't get it why polarized lenses in sunglasses don't show this orientation effect. I thought the different behavior is due to the use of linear polarizers. But that's obviously wrong.

Best.

Maybe this will help explain how polarized sunglasses work:

https://www.exploratorium.edu/snacks/polarized-sunglasses

And filters:

https://en.m.wikipedia.org/wiki/Polarizing_filter_(photography)

Or Google “How do polarized sunglasses work?”

Joe