This is a topic that you don’t hear much about and that took me quit a while on Google to dig up a few blog posts and forum comments concerning it. The simple fact appears to be that Nikon’s CLS underexposes when no on camera flash is part of the lighting. To prove it to myself for sure, I did an experiment.
Here’s a couple of simple (and ugly) shots to show you what I mean. All of them were shot with my Nikon D300s and one SB-900 at 1/125 second and f/5.6. The off camera flash is just to the right of the camera, at the same height and the same distance from the subject.

Off Camera SB-900 Triggered By The Master SB-900 On Camera. +1 EV Exposure Compensation On The Camera. Exposure is “OK.”
As long as the flash is on camera and is the light source for exposure, the exposure is “OK” with 0 EV exposure and 0 EV flash compensation. Using the on camera flash as only the master to trigger the off camera SB-900, the exposure is about 1 EV under. Dialing in +1 EV exposure compensation on the camera gets us back to the exposure provided by the on camera flash at 0 EV compensation.
Now why don’t we hear anything about that from the famous CLS flash instructors? I’m looking at you, Joe McNally. :)





