Moon Filter

[randb]

So whats the difference between a moon filter and a variable polarizing filter? The VPF can be used to adjust the transmission of light between 1% and 40% (Orion). So if I adjust it to 13%, will it be the exact same as using a 13% transmission moon filter?

Thanks Guys.

[turbo-1]

A variable-pass filter made with polarized elements will allow you to "dial in" exactly the amount of transmission you want. This makes it more flexible and usable than a fixed-transmission filter. Think of the total amount of light collected in the aperture of your scope, then consider how bright the image of the moon will be if you use a long f/lr ocular, a moderate f/l ocular, and one of short f/l. Can you predict what will happen to the image brightness as you move to shorter f/l eyepieces? Wouldn't it be nice to have a single filter that can provide the appropriate amount of attenuation for each?