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Old Mar 12, 2007, 11:07 PM   #1
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What is the diffrence between 8x and 4x in filters? Which is better. Also can someone tell me what is the difrrence between the warm moose circular polarizer filter and the regular circular polarizer.
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Old Mar 16, 2007, 12:57 AM   #2
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The Moose polarizer is a combination polarizing filter and 81a filter.

According to Moose Peterson, ...Why would you want such a combo? Well, I feel the 81a is an essential filter for not only cleaning up colors by bringing them back to the 5500k of our film, but also "warming up" our images to make them psychologically "warm and fuzzy".

So, the difference is that the "regular" polarizer has a fairly neutral color balance where the Moose filter is slightly tinted towards the red end to "warm" the color balance. Many people prefer warm-balanced pictures to neutral.
You can get a similar warming effect by setting your camera's white balance to "shade" or "cloudy" when shooting in straight daylight, but I don't know if the effect would be greater or lesser than that produced by the 81a.

The 8x/4x you mention sounds like you're talking about neutral density filters. Here's what Hoya has to say about their ND filters:

Neutral Density filters have several uses and offer the possibility to achieve otherwise unachievable results. ND filters appear grey and reduce the amount of light reaching the film. They have no effect on color balance.

They have four main uses:
1) To enable slow shutter speeds to be used, especially with high speed films, to record movement in subjects such as waterfalls, clouds, or cars.
2) To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background.
3) To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situations.
4) To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure.

Neutral Density factors:
NDx2 (exposure adjustment = 1 stop, reduces ISO 1/2)
NDx4 (exposure adjustment = 2 stops, reduces ISO 1/4)
NDx8 (exposure adjustment = 3 stops, reduces ISO 1/8

So, which one is better depends on how dark a filter you think you want for the type of effect you want to try to achieve. Most people that use ND filters have several in different strengths so that they can choose the correct one for the subject at hand.

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