Polarising Filter

[dxqcanada]

That's why I walk around with my polarized sun glasses and constantly tilt my head 90 degree's to either side ... yes, other people observing me may think I am really "odd".

 

[Winona]

I used one for the first time practicing waterfalls this weekend. Didn’t have a ND filter. The circular polarizer did allow a longer shutter speed. Not as long as the ND would have though.

 

[petrochemist]

From what I understand a polarizer blocks? filters? (not sure what describes it best) horizontal rays of light rather than vertical ones, but they actually move at various angles (which is why as you turn the polarizer more/different rays of light are blocked/filtered - I think, I'm a teacher but not a scientist working in a laboratory...! lol). I've understood it to mean that the horizontal rays coming at that angle directly into our eyes are the ones that cause more glare as we see it, that cause us to squint.

If I'm using a film rangefinder I'm not looking thru the lens so am seeing the existing light, not the filtered light coming into the camera (if I have a filter on the lens). But I know I've had to adjust exposure for the different/less/filtered light coming in to the camera. I haven't used a polarizer in awhile since the last time I went to a lake near me I was shooting Polaroids. (And yes, polarizing light technology had something to do with inventing Polaroids but I'd need a refresher on Edwin Land to remember what it was!)

I've used a circular one and it's just like RVT1K described, when you turn it you'll see the effect as you're looking thru the viewfinder and thru the lens. I haven't used one with my digital camera, and don't use one often, just sometimes shooting B&W film (with mechanical not auto film cameras) on sunny days near a lake etc. I don't often use lens hoods either but I can see why you can't when you've got to turn/rotate a circular polarizer.

I think horizontal is a bad term to use, which probably comes from reflections from water which are the main source of glare dealt with by polarizing glasses. Reflections from a vertical window will be polarized relative to the windows surface so will be vertically polarized. I have no issues with the word blocks though it's unspecific & would be appropriate whether the light was either absorbed or reflected
It is possible to use a polarizer with a rangefinder, determine the correct alignment by looking through the filter off the camera then mount the filter & replicate the same alignment. Certainly more of a pain than an SLR & you won't get the alignment quite right but you should get within 10°. Metering if not TTL would be awkward though.
Also lens hoods are possible with polarizers, either use a Pentax type one with a cut out window allowing rotation, or simply screw a round one onto the outer threads of the filter.
I can't advise on the relationship with polaroid cameras.

 

[smoke665]

Here's a good read with examples How to Use a Polarizing Filter I'd never thought of using a CPL to reduce haze

 

[carusoswi]

There remain some slightly confusing statements in this thread. The video to which smoke665 offers a very good description of how a polarizer works, where it can be useful, and when it may cause problems. The example of the water where reflections of the trees are eliminated by the polarizer is a situation where the photographer's taste comes into play. If you really want to capture detail below the surface of the water, then, the polarizer is your friend. If the reflection of the trees is an important part of your creative intent, then you would want to minimize the polarizer's effect.

I believe we should also keep in mind that a polarizer will have an effect on light, no matter its source. If you are shooting indoors at an aquarium, for example, a polarizer can be very useful when shooting through aquarium glass. The trade off, of course, is that, used at its maximum effectiveness, a polarizing filter robs you of at least a stop, often more than a stop of light. Many aquaria are dimly lit, and their inhabitants are in constant motion. This is another of the inversely proportional choices by which we photographers are challenged. I, personally, have experienced great success and great failure in capturing aquarium shots using both approaches. Higher ISO helps to compensate for the loss of light, and also helps to "freeze" motion, but results in greater noise. A larger aperture helps with light, but reduces depth of field. I love photography.

Back to polarizers, they can be helpful when shooting subjects wearing glasses to reduce those photo-ruining reflections that obliterate the subject's eyes, whether indoors under artificial light, or outdoors in sunshine. On the other hand, a poloarizer might also eliminate coveted catchlights (pleasing reflections) in the subjects eyes (I love photography!).

This has been an informative discussion. I am glad I came across this thread.

Caruso

 

[petrochemist]

There remain some slightly confusing statements in this thread. The video to which smoke665 offers a very good description of how a polarizer works, where it can be useful, and when it may cause problems. The example of the water where reflections of the trees are eliminated by the polarizer is a situation where the photographer's taste comes into play. If you really want to capture detail below the surface of the water, then, the polarizer is your friend. If the reflection of the trees is an important part of your creative intent, then you would want to minimize the polarizer's effect.

Caruso

You are not minimizing the polarizers effect when boosting reflections you are just using it to block light polarized in the orientation that is used for viewing under water, i.e. using the polarizers effect in a different way. If you take the polarizer off the reflection will be weaker than it is with the CPL rotated to maximize reflections.

 

[Derrel]

Sometime polarizing away reflections can render subjects in an unnatural way, such as on the surface of bodies of water.

 

[carusoswi]

Petrochemist:

Perhaps I should have said "then you would want to minimize the polarizer's effect on those reflections". In any case, I am referring to what results for the photographer when he/she rotates the filter. In practical use, the filter can either allow those reflections to show (I've never checked to see if they are stonger when showing through the filter or with the filter removed) or not show them. I, as most posters in this thread, am only casually familiar with what is actually happening. I know what the filter does from observing it in use and from observing the results. For me, that is good enough. YMMV.
Thanks.

Caruso

 

[Dikkie]

I don't use it that often.
Have not so good experiences with it... as I mostly decided to use it in sunny weather, I first put sunscreen on... and then I notice I need to screw on the filter with my fat fingers and I mostly touch the filter accidentally in the front and turns out I have a blurred surface I cannot get cleaned right away.... sunscreen all over the place.

Filters are fun though;...

 

[weepete]

CPLs can also cause X banding in the sky when used with wide angles, sometimes it can be quite exteme. But they can be used to cut reflections and deepen blues in the sky, just need to be a bit careful about how you use them.

I used to use them all the time, but I'm starting to move away from them except in spesific circumstances.

 

[petrochemist]

Petrochemist:

Perhaps I should have said "then you would want to minimize the polarizer's effect on those reflections". In any case, I am referring to what results for the photographer when he/she rotates the filter. In practical use, the filter can either allow those reflections to show (I've never checked to see if they are stonger when showing through the filter or with the filter removed) or not show them. I, as most posters in this thread, am only casually familiar with what is actually happening. I know what the filter does from observing it in use and from observing the results. For me, that is good enough. YMMV.
Thanks.

Caruso

If you really want to minimise the polarizer's effect, simply take it off
In one position it will maximise reflections from a surface, rotating it by 90° will minimise those reflections, the intermediate positions cover the whole range of options in between. One of these will give the same balance between reflected & transmitted light as you get without the polarizer.
How effective the polarizer is will depend on how the light is coming at the surface, the maximum effect is when the light hits the surface at 'brewsters angle' at which point the reflected/transmitted light is most heavily polarized.

In each case the polarizer is blocking light of a particular polarization. This increases the relative amount of the opposite polarization but doesn't actually boost it...

 

[RVT1K]

I have noticed something and I was wondering if it might be applied to photography.

When wearing a motorcycle helmet with a polarized shield and polarized sunglasses at the same time, I have on occasion noticed some strange effects. Mostly odd colors on the edges of leaves like very electric blues.

Has anyone out there ever stacked polarizing filters and if so were there any strange outcomes?

 

[petrochemist]

Has anyone out there ever stacked polarizing filters and if so were there any strange outcomes?

I can't explain the effects you've reported but stacking CPLs back to back gives very weird color effects. (Front to front works as a variable ND)

 

[RVT1K]

Has anyone out there ever stacked polarizing filters and if so were there any strange outcomes?

I can't explain the effects you've reported but stacking CPLs back to back gives very weird color effects. (Front to front works as a variable ND)

That is interesting. I wonder if both filters are closely aligned, there is diffraction interactions? Pure speculation on my part.

 

[petrochemist]

Has anyone out there ever stacked polarizing filters and if so were there any strange outcomes?

I can't explain the effects you've reported but stacking CPLs back to back gives very weird color effects. (Front to front works as a variable ND)

That is interesting. I wonder if both filters are closely aligned, there is diffraction interactions? Pure speculation on my part.

Not diffraction, It's down to the 1/4 wave part that makes the difference between CPLs & the linear polarizers, but I have to admit I'm not sure how they work. - There's always something else to learn isn't there!