[viovanda]

thanks all bros

[jsklee]

I suggest you to read a book called "Film and Digital Techniques for Zone System Photography". $70 only.

[viovanda]

but in canon camera,we need to cal the monitor or ??

[Obi-Wan]

If you mean GREY card, it can be used to 反射式測光或色溫，又可以影張灰咭相，using it as a reference of color temperature for further editing work

[viovanda]

i mean 灰階 photo

[jsklee]

do you mean black and white photo?

[viovanda]

black and white photo is difference from 灰階 photo

[jsklee]

so what is 灰階 photo?