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  #1  
Old 04-15-2008, 04:55 PM
AROBN54 AROBN54 is offline
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Default Question on polarizers....

Sometimes when I use a circular polarizer, it works beautifully - the colors are wonderful. And then sometimes, I get this horrid bluish cast that I cannot get rid of. Not with filters, not with removing color cast, not with adjusting hue and saturation. It just flat ruins my pictures. They look like moonlight shots. I hate that. Can someone tell me why that happens and how I can avoid getting that awful cast??? Thanks,

Shelly
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  #2  
Old 04-15-2008, 05:41 PM
mossphoto mossphoto is offline
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Default Re: Question on polarizers....

Shelly, just a thought.

How do you have your color balance set up on the camera. If you have it set to auto, the camera may be interpreting something it "sees" incorrectly. Make sure you have your color space set correctly. That may clear it up.

As a rule, polarizers usually have a magenta cast to them, not moonlight blue.

Good luck!

~Vic~
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  #3  
Old 04-16-2008, 07:16 AM
rgarrigus rgarrigus is offline
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Default Re: Question on polarizers....

Hi Shelly,

Do you typically shoot in RAW format? If so you should be able to fix things by changing the white balance in PP. Often the best WB result comes from the "click" option where you can click on a middle gray area in your image.

Maybe you could post one to a workshop and we could have a look at what you are describing?

Cheers!

Bob G.
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  #4  
Old 04-17-2008, 01:42 PM
rushfan2112 rushfan2112 is offline
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Default Re: Question on polarizers....

Hi Shelly.

Two things:

1) Polarisers work at their 'strongest' when pointed at 45 degrees to the angle of the sun. They always have an effect but it's most pronounced when the sun is shining over your soulder at an angle of 45 degrees. blacked-out skies and vignetting are common effects.

2) If you use a circular polarising filter, it's not just 'on' or 'off'. If you twist it round, you can get it to reduce or increase in effect and take away some of the worst excesses.

I had a tendency to use one to saturate colours by removing reflections from surfaces. However, these days, I seldom use one at all - preferring to use a neutral density filter to equalise brightness of the sky and just give saturation a slight tweak if it's really needed (which it seldom is if the image is to remain true-to-life).

IMO, the only real use for a polariser is to take excessive glare off water surfaces or remove some of the haze if shooting into the sun on a coudy / bright day.

Hope this helps.

Paul.
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  #5  
Old 04-18-2008, 10:47 PM
picus picus is offline
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Default Re: Question on polarizers....

Hi Shelly,

the effect strongly depends on the angle you have compared to the sun, the north and the subject. Have a look through the PL filter an tourn around yourself 360: you'll see that the effect will be stronger in some directions than in others: that's because the sunlight gets polarized by the angle of incidence. Being inline or perpedicular to the rays changes the effect.

Pascal
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  #6  
Old 04-19-2008, 08:37 AM
rgarrigus rgarrigus is offline
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Default Re: Question on polarizers....

Hi Shelly,

Everyone here is correct about the angle from the sun and its effects on the polarization but even at its strongest it would not account for imparting a color cast across your image as you are describing. Polarizers also do more than remove reflections and saturate colors. They are very useful for accentuating shadows when desired.

Cheers!

Bob G.
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  #7  
Old 04-20-2008, 04:23 AM
AdrianW AdrianW is offline
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Default Re: Question on polarizers....

Hi Shelly,

I don't suppose you have any images that demonstrate this problem, that you can share with us? Just posting one as a Workshop on one of your images would help.

About the only thing that's springing to mind at the moment is the possibility that you're a linear polarizer, not a circular one.

Confusingly cicular vs linear doesn't refer to the shape of the filter (either can be round or rectangular), but the way the filter affects the light passing through it.

There's an easy way to tell which type you have, even if there are no markings on your filter. Hold the filter up in front of an LCD display, now rotate the filter in front of the screen. Then flip the filter over and rotate it fully again. A linear polarizer will show black at some point during the rotation on both sides; a circular polarizer will only go black on one side.

Linear polarizers are not compatible with most modern cameras due to their interaction with the beam splitters used inside the camera for things like metering and AF.

Hope that helps!

Adrian
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  #8  
Old 04-21-2008, 03:04 AM
AROBN54 AROBN54 is offline
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Default Re: Question on polarizers....

Hi, everyone,

I really appreciate the answers I've gotten. I am not used to coming to this forum, so I missed them for quite some time. I do shoot in RAW all the time. And some shots I make with a polarizer are wonderful, and some?? SUCK. Maybe even on the same day. I had to look really hard to find a shot like I was talking about because usually if I get them that way, I just delete them. I know I won't be able to do anything with them. There was one left, though. I took a whole bunch of shots of this scene I will be posting and thought I had deleted them all. It looks dirty or... I don't know how to describe how it looks to me, but I cannot fix them. They're horrible. Here is a link to the shot I will post it to as a WS.
Polarizer WS. I just don't understand it. Thanks though, for all the feedback...
Shelly
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  #9  
Old 04-22-2008, 04:33 AM
AdrianW AdrianW is offline
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Default Re: Question on polarizers....

It looks a bit dark in the midtones, there's a loss of contrast, and there's strong colour shift towards green. There's also some vignetting (darkening of the corners).

The sky doesn't show much polarization though; I'd have expected the blues to be deeper than they are. Did you remember to rotate the filter?

I've posted you a Workshop. Does that look closer to what you'd expect?

If you send me the RAW file I'm sure I could do a better job. Click the ContactMe link in my profile, and I'll email you back. I would post my address, but I don't want the SPAM harvesters getting it.
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