questions on white balance
 

1. When using a white card to set a custom white balance, is it possible to determine the temp value the camera selected?

2. The manual suggests recalibrating white balance after adding an ND filter. Why?

3. In digital photography, I've always used an 18% grey card when setting white balance (a grey card gives me both white balance and exposure). The H1 manual suggests using a white card. Is there a reason to use white vs grey in video?

Best,
Christopher

1. Not AFAIK. I suppose you could do something like set up a gray card and photograph it repeatedly with a different color temperature selected each time then set the auto balance, photograph again and analyze RGB looking for the closest matching color temperature.

2. Because the "neutral" filter isn't quite neutral.

3. No, not really. What is important is that the card is neutral and that it is properly exposed. Rather than a white or gray card I use a neutral frosted "filter" over the lens, point at the light source and press the button. The filter doubles as my lens cap, is always handy and doesn't have to be placed in the scene. I find this much more convenient than fiddling with cards.