Polarizing Filter

[Kaptekarev]

I had less then spectacular results on my outing with a polarizing filter. What did I do wrong? What is the main purpose of a polarizer? I wanted it to reduce the haze and make the sky more blue.

I was taking pictures in the early afternoon and trying to stay 90 degrees to the sun. I took some action shots with 1/3000 shutter and some landscapes with large depth of field. Most of the pictures came out dark. The action shots weren't very sharp, the landscapes were dark. Can a polarizer be used for action shots?

The polarizer, is on a bearing which allows it rotate when it's on the lens. Is it supposed to clocked to a specific direction (it has an indicator arrow)?

Equipment used:
10D
28-135 IS lens
Quantaray Circular Polarizer (1-2 Stops filter factor)

Is this a decent polarizer?

[robertwgross]

You can use a circular polarizer exactly the way you describe, but you may be getting the maximum polarized result. Try shooting the same scene as before, but rotate the filter around just halfway to maximum. That might get the necessary contrast effect on the sky without completely darkening too much.

---Bob Gross---

[rdenney]

kaptekarev wrote:
I had less then spectacular results on my outing with a polarizing filter. What did I do wrong? What is the main purpose of a polarizer? I wanted it to reduce the haze and make the sky more blue.

I was taking pictures in the early afternoon and trying to stay 90 degrees to the sun. I took some action shots with 1/3000 shutter and some landscapes with large depth of field. Most of the pictures came out dark. The action shots weren't very sharp, the landscapes were dark. Can a polarizer be used for action shots?

The polarizer, is on a bearing which allows it rotate when it's on the lens. Is it supposed to clocked to a specific direction (it has an indicator arrow)?

Equipment used:
10D
28-135 IS lens
Quantaray Circular Polarizer (1-2 Stops filter factor)

Is this a decent polarizer?




I don't know the quality of that particular polarizer because it is a house brand of a photo store chain and may be made by anybody. But even a poor-quality polarizer would not make the images excessively dark, though it might cause a noticeable reduction in resolution.

A linear polarizer can cause the problem you report because the Canon meter uses a beam splitter that is incompatible with linear polarization. Thus, the meter will be confused resulting in incorrect exposures. If your polarizer is for-sure a circular polarizer, that should not be the problem.

The appearance of the polarized image is something you have to set at the time you make the image. First, aim the camera at the scene you want to photograph, and then turn the front part of the polarizer until the image looks good to you. There will be a position where the sky is darkened--this occurs when the 90-degree reflections off the dust in the air are polarized out. You can also eliminate reflections from water and objects by rotating the filter. But each of these will require a bit different rotation.

Some scenes don't work that well with polarization, so it's something that has to impress you in the viewfinder as being an improvement. If you can't see the effect there, then maybe you shouldn't use it for that scene. I used to keep a polarizer on my camera all the time, seeking more color saturation and sky contrast, but often the results would be soot-and-chalk contrast that was out of control. Now, I use it only when the resulting colors are important to the drama of the scene. I'd never use it for action shots, depending on what you mean by action.

For example, here's an image that would have ruined by polarization, because it would have killed the reflections from the surface of the log:

http://www.rickdenney.com/images/burned_log_14mm_velvia_lores.jpg

Burned Log, Elan II, Sigma 14mm/3.5 at f/16

And it would have been dark, too, because the black of the soot on the burned log would have been the only color remaining.

As to why the images are dark, I have observed with film that polarizers often render medium shades rather dark depending on how they are lit. Often, in addition to darkening the sky, you'll remove the specular reflections from the ground with the result that it seems darker. But highlights like clouds are unaffected, and the meter will still try to keep them within the latitude of the image. Try pulling the curve up in Photoshop--I bet you'll find the tonality is all there. It just doesn't look right without those specular reflections.

Rick "a reformed over-polarizer" Denney

[cowman345]

If your shots are durning out dark, then some settings are not properly adjusted.

If you are shooting in full manual, make sure the exposure meter is set the way you want when looking through the viewfinder (you can't go from no polarizer to suddenly adding one and see no difference, it will allow slightly less light through and need compensation).

If you're shooting in any of the automatic modes with a circular polarizer there's nothing you have to worry about except your exposure compensation setting. If that's set too far under, then filter or not, your shots will be too dark.

-dave-