My first circular polarizer... real quick question

After seeing some of my shots through polarized sunglasses, and then seeing them through my camera lens, I realized that some of the outdoor / motorsports shots would benefit from a polarizing filter, so I ordered one.

My question is... do I just use creative modes and quickly bump the exposure comp up a notch or two when using the filter? Will I see the weight of the image drop towards the left in the histogram? If I shoot RAW does it really matter when I can easily adjust that minor exposure difference in PS CS?

Thanks for the help!
Adam

You shouldn't need to adjust anything. The camera will meter the scene with the polariser on and set the shutter / aperture values for correct exposure. It has no way of distinguishing between a dark-ish day and a bright day with a polariser.

Oh. well that's easy enough. Why have I heard people talk about adjusting exposure when using certain filters such as a polarizing filter?

Maybe I'm nuts.

Thanks!
Adam

The polarizing filter itself is dark and will take away between 1 and 2 stops of light (which means you have to use shutter speeds 2 to 4 times as long or open up the aperture 1 to 2 stops).

If you use the light meter in the camera, you don't have to adjust anything, because it measures the light that enters the camera through the lens. If you put the polarizer in front of the lens, it measures what it sees through the lens plus filter.

Only if you use a separate light meter and you set the exposure setting on your camera manually, based on what the light meter says, you must take the adjustment into consideration. The separate light meter doesn't know that you have a filter on your lens....

I may be teaching you to suck eggs if so forgive me, but don't forget to rotate your filter to get the desired/maximum effect.

N

You meter should take care of everything. A P filter will cost you two stops and even though everything in you body will cry out that it can't be true, you lose the two stops even when the Polarizer is not being particularly effective. So don't dial it in to get neat colours, and then dial it out to let in more light, 'cause it's all the same.

Gotcha... thanks guys! BTW, is there a standard rotation for the CP that works most of the time in standard landscape shots? Obviously sunglasses are fixed in one direction (I assume horizontal) so I was curious if circular polarizers have a mark for 'home' position or if you just spin away and find what works...

Adam

Hijacking the thread a little, why is it that a (C)P filter will cost two stops? One would think that since it cuts one half of the light (one of the two components), it should only cost one stop. Or is it just too early for me in the morning?

You're making EXACTLY the same mistake that I carried around in my head for 20+ years! I thought a Polarizer was two rotating pieces of glass in opposition to each other (ie, the front one rotates, and the back one doesn't move). In fact a Polarizer is only ONE piece of glass, and it rotates. Go and check on yours.

No, just look through the lens with the filter on and rotate it with your other hand until you see what you want. The effect of the polarizer also depends on where you point your lens in relation to the sun. It's most effective at a right angle (90 degrees) from the sun.

If it was only 100% cutting out one of the two components of each incident light ray while not affecting the other, it could. However, the polarizing material also has some non-directional absorption qualities, so it reduces the in-plane (polarized) component of the light as well. This is also true of plane polarizers (which are cheaper), so using a non-circular polarizer isn't the solution either (plus having some undesirable side effects on technology used for metering incoming light).