Polarizers

Going too far

I'll admit, when using a polarizer the image usually looks its best in the viewfinder if you turn the polarizer to its maximum effect. But that doesn't always create the best results.
Here I'm at an altitude of around 6000 or 7000 feet in Zion National Park. When you're at that altitude, it's easy to over do the polarization of the sky, turning it practically black.
You can use your spot meter to let you know what the difference between the sky and the red rock is. This picture was shot on Fuji Velvia 50 slide film and in this case, with the polarizer at full effect, the sky is probably two stops or more darker than the red rock. I wanted it to be lighter than that so I adjusted the polarizer, watching the sky brighten in the viewfinder and again measured the difference between the two. For the second image, the sky and rock are at about the same tonality.
With a digital camera, simply look at your histogram. If you see a big hump at the left side of the histogram you'll know something it too dark. Adjust the polarizer and watch that hump move more toward the center.