Question about Polarizers

wilonstott

wilonstott

Wil O.
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Simple.
Do they require hood?
The reason I ask--they reduce glare right?--does this make them impervious to lens flare?
Seems like a silly question--but the more I think about it, the more unsure I am.

Also, polarizers work best in bright sun (arguably) so I assume flare/glare is a potential issue. Hence the question 🙂.

Thanks guys.
 
While I agree that using a hood is best, it isn't essential. Sorry payasm. I often use my Voigtlander 28 1.9 ASPH with a polarizer and no hood.





And I use my Nikkor 28 1.4 AF-D on my D3 with a polarizer about 90% of the time during the day in order to shoot @ 1.4,
which is the same reason I use it on the 28 1.9 on the Leica M.



If the sun is directly hitting the front element, I find it helpful to flag (hold my hand up in order to shade the front element).
I hate to contradict what another says on this forum, but when it comes to information, you have to cross-reference
from a number of different sources and ultimately decide for yourself.

Gregory
 
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wilonstott said:
Simple.
The reason I ask--they reduce glare right?--does this make them impervious to lens flare?
Click to expand...

They reduce reflections off of surfaces, not ones that occur in the lens. When light reflects off of surfaces, it get's polarized. The polarizer can filter some of that out. However, light that makes it past the polarizer and into the lens can still create flare.

So while it might help reduce any flare coming from light reflected off of a sheet of glass, it's not going to help reduce flare you might get from the sun being at the edge of the frame.
 
Interesting question, technically. Because, polarized light will also reflect less inside the lens, depending on the polarization.

I were you, I would try.
 
ferider said:
Interesting question, technically. Because, polarized light will also reflect less inside the lens, depending on the polarization...
Click to expand...

Possibly, but these days people use circular polarizers much more than the old single element "linear" polarizers. Circular polarizers are two element affairs where the front element is a linear polarizer (this does the "work") and the second is a true circular polarizing element. This latter element effectively depolarizes the light so that it doesn't cause issues with the semi mirrored surfaces using is modern metering and AF systems.

Since a circular polarizer doesn't emit polarized light, the internal reflections will be just as significant as with any other filter. Since it adds two additional internal glass to air surfaces (front of the lens and rear of the filter), moves the front surface forward so that it is less recessed (bigger issue with some lenses than others), and presents a flat rear surface, it actually increases the need for a lens hood.
 
Circular polarizers do transmit polarized light. It's just circularly polarized, not linearly.

It doesn't cause issues with semi mirrored surfaces not because it's unpolarized, but because it's not linearly polarized.
 
The term "Circular Polarizer" as used in photography is different from "Circular Polarization" as you learn in Physics class and is found on the optics bench.

A "circular polarizing filter" is a linear polarizing filter with a 1/4 wave plate behind it to scramble the light that passes though the linear polarizing layer. SO: the linear polarized light is absorbed, the remainder is scrambled so that it is not cause problems hitting a mechanism used for spot-metering or AF that assumes non-polarized light is being received.

Nikon made a special series of Hoods just for use with the Polarizing filters. The Nikkor filters were oversized, so you could stack them with regular filters and not cause vignetting. My 72mm Polarizer with the matching Hood makes the 300/4.5 look like a real beast. The Polarizing filter with hood was a real winning combo at an Air Show.
 
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1/4 wave plates circularly polarize light. I don't see the inconsistency.

The linear polarizer linearly polarizes the light, which then passes through the quarter wave plate. If the quarter wave plate is oriented properly, the linearly polarized light is circularly polarized. Circularly polarized light doesn't cause problems with the semi-silvered mirrors used in metering and AF in cameras.
 
You will get the glare reduction effect (and darkening of sky) of a polarizer (rotated to the proper position) with our without a lens hood. You can see the effect just by holding the filter up and looking through it as you rotate it. Of couse, using a hood is always good, with or without a polarizer.

Polarizers do NOT necessarily work best in bright sun. They work in any situation where there is a lot of glare on the surface of an object, a wall, the water, any surface really. This can just as easily be an overcast day, or inside a building. Of course they require more exposure since they are dark.
 
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I recall what I read in the 1960s: "There is no photograph which cannot be improved with the use of a hood." I try to get the best out of my equipment and cannot understand why people regard hoods as a nuisance.
 




Nikkor 28 1.4 on D3 with 72 mm polarizer @ 1.4.

It's tricky using polarizers effectively with the Leica M system. The reason is that you're not looking through the lens to see the amount of polarization effect. And while I agree that using a hood is best, trying to find a hood that fits over the polarizer that doesn't vignette can be bothersome.

At any rate, I found that getting the maximum degree of polarization can be determined by turning the outer ring and watching the light meter in my M6/M7. The less light, the more polarization. Of course, it's easier to use with an SLR/DSLR. But I enjoy the challenge and like the results with the polarizer with the 28 1.9 on the Leica M film cameras. And although I don't use a hood, that's not going to stop me from benefiting from using the polarizer.





Leica 28 1.9 ASPH with polarizer on Leica M7.

Gregory
 
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I try not to use a lens without a hood whether I have a filter or not. The Leica M series has it's own polarizing filter 13352 with a built in hood. It clamps to certain lenses like my Summicron M f2 that have the 39mm filter mount.
I've used it successfully and often with my 35mm and 90mm lenses.

No vignetting with the 35mm...none but I don't know how it would affect a TTL meter. Using a handheld meter I compensate by +2 stops.
 
Tim Gray said:
...The linear polarizer linearly polarizes the light...
Click to expand...

To say that a polarizer "polarizes" the light is some what incorrect, grammatically. A polarizer does not, in any way, alter the wave orientation of the light striking it and using an active verb to describe its action is somewhat inappropriate. A conventional "linear" polarizer either passes light or absorbs light based on the orientation of the light. If no light is of the proper orientation to be passed, none passes.

The 1/4 wave plate, on the other hand, actually alters the wave orientation of the light passing through it. The number of degrees the polarization angle is altered varies with the frequency of the light. If the light passing through a properly designed plate is reasonably evenly distributed across the spectrum, the light exiting the plate is essentially "unpolarized" as there is an even distribution of light at all wave orientations.
 
Leica M Polarizer

Leica M Polarizer

Leica M polarizer:

Pol1.jpg
pol2.jpg
pol4.jpg
Pol3.jpg
 
Dwig said:
To say that a polarizer "polarizes" the light is some what incorrect, grammatically. A polarizer does not, in any way, alter the wave orientation of the light striking it and using an active verb to describe its action is somewhat inappropriate. A conventional "linear" polarizer either passes light or absorbs light based on the orientation of the light. If no light is of the proper orientation to be passed, none passes.

The 1/4 wave plate, on the other hand, actually alters the wave orientation of the light passing through it. The number of degrees the polarization angle is altered varies with the frequency of the light. If the light passing through a properly designed plate is reasonably evenly distributed across the spectrum, the light exiting the plate is essentially "unpolarized" as there is an even distribution of light at all wave orientations.
Click to expand...

Right about the first part.

The second part I take issue with, but that's fine. Circular polarized light is different from randomly polarized light. Look up 1/4 wave plates. When set to the right angle relative to incoming linearly polarized light, they circularly polarize it. Read about circular polarization. Look up depolarizers. Make your own judgements. I was just trying to point out a common misconception, but if people keep telling me I'm wrong, whatever, I'll move on.
 
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Dwig said:
To say that a polarizer "polarizes" the light is some what incorrect, grammatically. A polarizer does not, in any way, alter the wave orientation of the light striking it and using an active verb to describe its action is somewhat inappropriate. A conventional "linear" polarizer either passes light or absorbs light based on the orientation of the light. If no light is of the proper orientation to be passed, none passes.

The 1/4 wave plate, on the other hand, actually alters the wave orientation of the light passing through it. The number of degrees the polarization angle is altered varies with the frequency of the light. If the light passing through a properly designed plate is reasonably evenly distributed across the spectrum, the light exiting the plate is essentially "unpolarized" as there is an even distribution of light at all wave orientations.
Click to expand...
Strictly speaking, you're right that a linear polariser doesn't polarise light, it just passes the correctly orientated light. The net effect is as though it did, with some loss.

As for a quarter-wave plate, that also behaves in the same way but the plane of polarisation rotates at the same frequency as the wave, so the polarisation corkscrews through space. It's NOT unpolarised though. The reason for using circular polarisers is that AF and some metering systems react the same to circularly-polarised light as they do to unpolarised but they don't work with linearly-polarised light. Circularly-polarised light is *effectively* the same as unpolarised for these systems but it is not "essentially" the same.

Incidentally, the same technique is applied to some radio signals and the transmitting and receiving antennae have to be "handed" the same way (clockwise or anticlockwise, as the case may be) for maximum reception. Use opposite antennae and get negligible signal!
 
Like wolves3012 just said about radio waves being "handed", circular polarizers are also "handed". Did you ever notice on Tiffen circular polarizers that some have a white circle on the rim that is black in the middle and some have a solid white dot. Well, one marking means they are polarized in one direction and the other marking means they are polarized in the other direction. I don't know which is which. Just try this experiment: put two Tiffen circular polarizers, similarly marked, back to back. You will find it is easy to see through them. Next put two Tiffen circular polarizers having different markings back to back. Now the view through them is almost black! What? You never noticed? Of course you did!
 
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