On Mon, 05 Aug 2002 22:20:51 GMT, Colyn wrote:

>The number is the exposure adjustment for that filter. However, if you
>are using through the lens metering the meter automaticly
>compensates..

Actually, I find this not to be true (at least with
older Nikon bodies...). The color error in the camera
meters roughly "half-compensates" for the filter, and
1/2 the rated compensation needs to be added... (as in,
a 1-stop dark yellow needs 1/2 stop added to the exposure
determined by the TTL camera meter, a 2-stop orange needs
1 stop added, and a 3-stop red filter needs 1.5 stops
added). You can easily check this by metering a grey
surface in the same light and at the same angle with and
without the color filters, and comparing the TTL meter
compensation made by the meter with the filters' rated
needed compensation...