screws onto the end of your lens, then you rotate the filter until you get the effect you want: either the sky gets deeper blue, the glare on water or glass is gone etc.. If you don't have it set right, you're not actually getting its true effect.. but I'm not sure if a variable is the same as a radial.. SOUNDS like it is - do you spin the variable to get better shots?

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Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..