polarized glasses vs camera polarizer

[Cartooniverse]

@Baal_Houtham

Your original statement was entirely clear to me — unlike the Wikipedia explanation of circular polarizers. I’ll have to give that one another go, after I’ve been awake a few more hours.

Diffusion? That’s ENTIRELY different !!

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[scr4]

@CalMeacham

I have to admit that I never really considered the direction of polarization of polarized sunglasses, but to have them vertically polarized makes sense – it’s more likely to counter unwanted reflections from horizontal surfaces then. But polarization in any direction will almost certainly reduce some glare, because it isn’t all coming from reflections from horizontal surfaces.

Sunglasses with horizontal polarization would reduce glare from vertical surfaces, like building windows. But it would increase glare from horizontal surfaces by preferentially transmitting the reflected light.

[CalMeacham]

@scr4

Sunglasses with horizontal polarization would reduce glare from vertical surfaces, like building windows. But it would increase glare from horizontal surfaces by preferentially transmitting the reflected light.

Exactly. There’s no one direction that’s best for polarization, and you can see how you get varying degrees of attenuation of the glare from various angled surfaces, which is why I never considered the direction of polarization in sunglasses.

But it does make sense to position them to minimize horizontally-polarized light from flat horizontal surfaces, like bodies of water, which are probably more common that other angles

[shinnen]

Hi,
Well, I don’t know what the person who said that he uses a filter to protect his lens was using. He may have been implying a UV filter; but from my discussions on camera forums I know that there are people who regularly leave a polarizer on their camera. Of course, you will lose a stop or two, depending on the polarizer.
…john

[beowulff]

@CalMeacham

Exactly. There’s no one direction that’s best for polarization, and you can see how you get varying degrees of attenuation of the glare from various angled surfaces, which is why I never considered the direction of polarization in sunglasses.

But it does make sense to position them to minimize horizontally-polarized light from flat horizontal surfaces, like bodies of water, which are probably more common that other angles

It’s not just bodies of water, but roads and cars themselves which tend to be polarized horizontally.

[Telemark]

@shinnen

but from my discussions on camera forums I know that there are people who regularly leave a polarizer on their camera. Of course, you will lose a stop or two, depending on the polarizer.

If you don’t need a polarizing filter for a shot, why would you leave it on your lens? I can’t say that no one does that, but IMO it’s a very poor choice that doesn’t help your photography in most situations, and hurts your photography often.

[shinnen]

@Telemark

If you don’t need a polarizing filter for a shot, why would you leave it on your lens? I can’t say that no one does that, but IMO it’s a very poor choice that doesn’t help your photography in most situations, and hurts your photography often.

Yes, I don’t do it either, but I’ve talked with people who do.
I guess there are pros and cons depending on what you’re shooting.
… john

[Robot_Arm]

@beowulff

It’s not just bodies of water, but roads and cars themselves which tend to be polarized horizontally.

I thought it was the other way around; that light reflecting off a horizontal surface (like a road or a body of water) becomes polarized vertically and is blocked by horizontally-polarized sunglasses. I worked through the math of it in Physics class, but that was ages ago.

[Telemark]

@shinnen

I guess there are pros and cons depending on what you’re shooting.

I leave mine on when I’m shooting a skiing event, but that’s for the specific conditions of the day. There really isn’t a general purpose reason for keeping one on for all shooting.

[beowulff]

@Robot_Arm

I thought it was the other way around; that light reflecting off a horizontal surface (like a road or a body of water) becomes polarized vertically and is blocked by horizontally-polarized sunglasses. I worked through the math of it in Physics class, but that was ages ago.

Polarization by Reflection
Unpolarized light can also undergo polarization by reflection off of nonmetallic surfaces. The extent to which polarization occurs is dependent upon the angle at which the light approaches the surface and upon the material that the surface is made of. Metallic surfaces reflect light with a variety of vibrational directions; such reflected light is unpolarized. However, nonmetallic surfaces such as asphalt roadways, snowfields and water reflect light such that there is a large concentration of vibrations in a plane parallel to the reflecting surface.

From here: Physics Tutorial: Polarization

[Turek]

@shinnen

Yes, I don’t do it either, but I’ve talked with people who do.
I guess there are pros and cons depending on what you’re shooting.
… john

I would say that they are very amateur or clueless.

For instance, you very seldom want to use a polarizer on a wide angle shot with lots of sky, because the light is polarlized differently across the sky and this will result in a weird effect where the sky is darkened more in some places than others.