You are right, 18% grey is used in the film days to

check for exposure, but also lots of professionals using 18% grey as a test shot for each roll of film.
What they do is shoot the first frame with the 18% grey card, then in processing the film, the lab using the grey card to adjust color balance.

In digital days, we still can use the 18% grey card for exposure, but for white balance for digital sensor, a differnt kind of grey is used, this is the card I use for white balance.



the white is a good referance card for preset, but you need a big one, or you can use one of the grey card.
Notice there are two grey card in the picture, the one in the middle is 18% grey, the other one is the grey card for digital imaging.

所有跟帖： 

• 谢谢指导， -尘埃之花- ♀ (99 bytes) () 07/15/2007 postreply 14:45:48

• It's used for post processing raw, -天逸- ♂ (128 bytes) () 07/15/2007 postreply 16:29:21

• 我晕了： -尘埃之花- ♀ (77 bytes) () 07/15/2007 postreply 16:52:59

• 尘花没仔细看说明书。preset要求是用gray or white。灰卡是首选 -simpledreamer- ♂ (0 bytes) () 07/15/2007 postreply 21:56:18

• 汗，梦游了。谢谢点拨！ -尘埃之花- ♀ (0 bytes) () 07/15/2007 postreply 22:56:05