[jms698]

The way I see it there are four ways to white balance on Pentax cameras:

1. Use auto white-balance.
2. Shoot a grey card (or expo-disc) and use that to set the white-balance in post processing.
3. Use the camera's various presets for different lighting conditions (tungsten, sunlight, etc.)
4. Shoot a white surface and use that to set the custom white balance in camera.

Which do you use and why?

I'm interested in people's experiences with using option #4. Does white balancing "out in the field" work as well as in post? If it does, that might save me some time at the computer.