I just bought a used D90 to get commander mode in the camera body (I also have a D5100). I have set the SB700 flash to remote. I have set the camera to commander mode and for the built-in flash I've selected "--" so the built in flash is not supposed to fire. The SB700 goes off fine, but the built in flash fires every time. Suggestions on how to fix this? If it's a defect in the camera, I need to return it asap. Thanks.
#1. "RE: Commander mode in D90" In response to Reply # 0
Farmington Hills, US
The built-in flash fires a sequence of flash pulses to determine the remote flash power for TTL metering and set the remote power level. This happens before the camera shutter opens. Then the built-in must send one more pulse to trigger the remote for the actual exposure. If the built in is set to "--" this final pulse is weak and shouldn't have any effect on the actual exposure.
This weak pulse could cause an annoying catch light in a subject's eyes. To eliminate any affect from the built-in trigger pulse, Nikon makes the SG-3IR. The SG-3IR fits in the hot shoe and blocks all visible light from the built-in flash from going forward. The SG-3IR allows the infra-red portion of the flash output to go through. It's the IR that is interpreted by the remotes for control.
Gary in SE Michigan, USA. Co-organizer of the Southern Michigan Chapter Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300, D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery
Gary is right. Unless you are very close to your subject, with the built in Speedlight set to "--" the triggering pulse will not contribute to the exposure. If there is a reflective surface in the frame, the flash will reflect and be captured in the image as the highlights in the eyes as mentioned above. Good Luck and Enjoy your Nikons!