Manual white balance Question

[gll]

I was just looking at Joe's images he shot with Russel and notice he used manual white balance. I have tinkered with this but really just do not understand it, I know all situations are different but is there a rule of thumb or sunny 16 type rule or something to guide you.
thanks
Gary

sorry just realized I was in wrong forum, not sure how to undo this ?

[momech]

Don't know how you do it on a Nikon, but there should be a menu option for Custom WB (or the equivalent). Take along a white or grey card, and use this in the light you'll be shooting to manually set the WB. On a Sony, once you've set the camera to "Custom Set", you just aim at the card and shoot a frame; doesn't have to be in focus, etc. This tells the camera's computer what white looks like in the light you've got, and it uses this as a base point to adjust the rest of the spectrum.
There are some gizmos on the market you use by covering the end of your lens, but I have no experience with any of them.