Circular Polarizer troubles

[kmg365rb]

I have a new circular polarizing filter for my new Nikon D5000. When I take pictures I usually get one quadrant of the image with a darker blue patch. I've tried twisting the front of the filter with little change, though the effect does lessen. Any ideas for how I can fix this trouble? Can you tell me how best to use this filter?
Thanks very much,

[Elmo]

Would be nice to have an image to give an idea of what you are talking about. But from your brief description my first thought is you are using your CPL (I assume you are using a CPL not a PL) on a wide angle lens. As a CPL effect varies with the angle of the sun a wide angle covers a wide angle, therefore the effect can change over the frame.

[dcclark]

Originally Posted by kmg365rb

I have a new circular polarizing filter for my new Nikon D5000. When I take pictures I usually get one quadrant of the image with a darker blue patch. I've tried twisting the front of the filter with little change, though the effect does lessen. Any ideas for how I can fix this trouble? Can you tell me how best to use this filter?
Thanks very much,

What lens are you using this with, and at what focal length? If it's a wide angle (such as the 18mm end of the kit lens), then this is exactly what should happen. The amount of polarization varies depending on which part of the sky you're looking at, and a wide angle lens sees a LOT of the sky.

[OsmosisStudios]

Polarization effect is strongest at 90 degrees from the sun, so if you're facing it (or it is to your back) then it is your immediate left or right (9 or 3 o'clock).

If you're aimed at a 45 degree angle, it's normal for it to vary from one side to another.

[ChrisPhilip]

I have a CPL on my kit lens, havent had much time to play around with it but a simple question. When I twist it, should I notice any differences in the viewfinder, from what Ive seen so far there hasnt really been a noticable difference. Maybe I just need to get out and use it more.

[dcclark]

Originally Posted by ChrisPhilip

I have a CPL on my kit lens, havent had much time to play around with it but a simple question. When I twist it, should I notice any differences in the viewfinder, from what Ive seen so far there hasnt really been a noticable difference. Maybe I just need to get out and use it more.

You should see a difference IF you're pointing at something which will be affected by the polarization.

For example, take your polarizer outside on a sunny and clear day. Point your camera (with the polarizer on the lens) at a point 90 degrees away from the sun -- so if the sun is roughly in the northwest, point it northeast or south west. Then turn the polarizer, and you should see a dramatic change.

Similarly, you can usually see a dramatic change when looking at green grass, leaves, etc. on sunny days.

Finally, try pointing your polarizer at glass or water which has a lot of reflections in it. Turn the polarizer, and you should see the reflections partly or wholly disappear.

[Elmo]

Our eyes seem to have some built in polorization. This is the reason we often see detai the camera "misses" So when we look thru the viewfinder the effect seem minimal but to the recorded image it is dramatic.

As a side note most CPL's have a mark on the rotating ring. It varies from a small dot to a triangle. I saw one one time it was a dot with rays around it. Rotate the ring until the mark is toward the sun and you should be close to maximum effect.

[ChrisPhilip]

thanks guys, I hope I can find the time soon to actually get out and use my camera, school has me busy all day long. Hopefully Ill get to actually use the CPL and figure it out.

[111t]

The effect will be most noticeable on transparent surfaces such as glass or water. On other surfaces you will notice it as it affects the bluish hazy reflection off of objects. I notice this especially on vegetation.