Circular Polarizers creating rainbows..?

[gx680lugger]

Has anyone else noticed small spots of rainbow like distortion in high key areas (especially the sky) of images taken through circular polarizers? I own several different high quality circular polarizers and I have noticed even in the viewfinder that they sometimes create a rainbow color distortion spot in the frame.

[mike_rott]

Not sure if I am understanding this correctly. Are you refering to very bright sections of cloud? It may not be a problem with your polarizer but an actual rainbow effect in these areas. Your polarizer just makes it easier to see it. I see this now and then in the evening when the sun is lower and with sunglasses on. Depending on the cloud formations one can sometimes see a fragmented rainbow partially around the sun. Most times you see only one or two small sections. To the naked eye it is hard to see, it looks like just a bright spot with maybe a hint of color if you are paying attention.

 

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mike

[don_carter1]

I have seen the rainboe effect that Mike mentioned. Especially in the winter, but this is something different. I am sure there is a reason for it, but I have no idea what that reason might be.

 

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The "rainbows" are in the filter itself. I can see them move with glass of the filter as I rotate it. I have noticed this in two different circular polarizers, One was a 77mm Hoya, the other a 65mm B&W(?) The distortion has only shown up in circular polarizers. If the distortion happens to be in a lighter area of the image, it shows up on the film. None of my normal pola filters have ever exhibited this strange anomaly.

[struan_gray]

I would guess this is a result of multiple reflections inside the

 

filter which will result in interference fringes just as with oil

 

on water or Newton's rings. Such an effect would be more apparent

 

in a cicular polariser for two reasons. First, there is an extra

 

interface between the linear polariser and the quarter wave plate.

 

Second, the quarter wave plate behaves differently for different

 

wavelengths and so will spread the colours out more.

 

 

 

If this is the cause I would expect the problem to be worse at the

 

edge of the frame and for it to be visible if you take the filter

 

off the camera and just look through it. The effect may look worse

 

in the viewfinder if you have a semi-silvered mirror that acts as a

 

second - partial - polariser.

[don_carter1]

You are correct Struan, the colors are more visible when looking straight through the polarizer, off camera. They are less noticeable in the viewfinder, and even less on the film, but, they are there. I have had several shots that were wrecked by this. I looked at every circular polarizer in a photo shop here in Kanab, and they all did it to some extent.

 

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Thanks for the explanation. I will cancel my Tuesday therapy session dealing with hallucinations.

[joshua_kistler]

I have never had the described rainbow effect with my Tiffen Circular

Polarizer while looking at the sky, only while taking pictures through

water and glass (ie. taking pictures through a dolphin viewing window

at a oceanic aquarium)...Although this can lend to some extremely

interesting shots at times...

[ryszard_stasinski]

And what about the following effect - depending on the filter position

image changing from warm to washed-out of warm tones, but only in the

camera viewfinder (EOS 10, somewhat less in EOS 5)??? The filter

itself is OK, and not only because it is B&W, indeed. No such an

effect on Mamyia M645 with CDS prism.

 

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Ryszard Stasinski