i just set it to "--" and it still fires when i use the cam in commander mode.
Whichever of the 2 settings you put it to, the popup flash will still fire because it needs to communicate with off camera flash. It's just if you put it to -- then the popup doesn't contribute to the exposure. With my D70s I don't have that option, it just doesn't contribute to the exposure at all unless I'm at a high ISO or a very large aperture or very near the subject. The off camera flash won't fire if the popup didn't fire. That's how they communicate.
i still dont know why it has to fire though. if its controlled by infrared instead of the oight from the flash...why does it need to fire. too advanced for my simple brain. i'll just do what i'm told.
D800e l V3 l AW1 l 16-35 l 35 l 50 l 85 l 105 l EM1 l 7.5 l 12-40 l 14 l 17 l 25 l 45 l 60 l 75 flickr
I am pretty sure the on-board controller communicates via pre-flash signals to the remote unit(s). I guess I am going to have to confirm this by looking it up... but I think the SU-800 and SB-800 controllers might communicate via another method?
Ok, without confirming the SU-800 and SB-800 the D80 manual does explain (p 96 - 97) that the pop-up flash will need to be up so that the "timing" sequence can be sent to the remote flash units. It also makes suggestions as mentioned previously to keep iso low, and exposure settings at levels that will not be affected by the pre-flash series.
Nikkor 50mm 1.8D (If you don't have it you need it)
Nikkor 18-200mm VR II
NAS (D300, Nikkor 80-200mm (or 70-200mm)f/2.8, Tamron 90mm Macro)