[hehehaha]

the correct exposure of a composition is 1/125sec, f5.6
does it apply to both of day and night time?

[samlau]

It only applies to ONE PARTICULAR SITUATION, can be night time, can be indoor, can be outdoor.

What are you trying to say?

[samlau]

Guess I know what you are thinking, you quoted it from one of my replies, didn't you?

What I was saying is, I F the correct exposure for a situation, a shot is, FOR EXAMPLE: 1/125 sec f5.6, it is the same as a exposure of 1/250 sec f4, 1/60 sec f8, etc., regardless of depth of field and other variables, just the exposure.

If you think 1/125 sec f5.6 is the "universal" exposure for taking most pictures, it is NOT the case.