Exposure Steps
Prepared 2009-02-04 and revised 2009-02-11 by Bill Claff

Typical Nikon DSLR exposure steps:

 

P

S

A

M

◄ Follow the column for the Mode chose by the photographer

1a) Photographer sets explicit ISO

 

 

1b) Photographer sets aperture

 

 

1c) Photographer sets shutter time

2a) If ISO Auto is On and ISO is “Lo” then camera sets ISO to the lowest numbered ISO; the low ISO limit

2b) If ISO Auto is On and ISO is above the Maximum sensitivity then camera sets ISO to the Maximum sensitivity; the high ISO limit

3a) Camera performs metering

3b) Camera adjusts meter reading for Exposure Compensation

 

 

 

4a) Camera sets aperture and shutter within body and lens limits based on the program (or modified program) for the ISO and metering

 

 

 

4b) Camera sets aperture within lens limits based on the ISO and metering

 

 

 

4c) Camera sets shutter speed within body limits based on the ISO and metering

 

 

5) If ISO Auto is On and shutter is slower than the Minimum shutter speed then camera sets shutter to the Minimum shutter speed

6) If ISO Auto in On and the aperture/shutter combination is not a correct exposure then camera sets ISO within the ISO limits

 

 

7) If ISO Auto is On and the aperture/shutter combination is not a correct exposure then camera sets shutter speed within the body limits

 

 

8a) If flash and using front-sync, rear curtain sync, or red-eye reduction; then camera limits shutter speed to no slower than Flash Shutter Speed

8b) If flash then camera limits shutter speed to no faster than Flash Sync Speed

Note that steps only apply if there is an arrow (►) pointing to that step in the column for the Mode the photographer has chosen (P, S, A, or M).

Note that yellow steps apply only when ISO Auto in On and cyan steps apply only if the body is aware that flash is being used.