On 16 Oct 2002 20:53:28 -0700, djon8@hotmail.com (DJ) wrote:

>I was reading an old post, and the statement was made that higher
>speeds lower the effective guide number. Can someone shed more light
>on this?(didn't mean to do that). Are there some figures or formulas
>for this? Thanks,

If the higher shutter speed is within the normal synch.
range of the camera, there is no affect on guide number;
if not, and it is achieved using multiple flashes, then
each flash must be at a lower than maximum output,
lowering the guide number (the amount depends on a few
variables, so is particular to the flash used....).