The other day, I discovered why portrait subjects shot with Nikon Commander mode so often have their eyes shut!
On the surface, Commander mode is a great tool. You can remotely control the all the settings on one or more Nikon Speedlights directly from a Nikon DSLR. Menu settings on a cameras like the D7100, D610, etc allow you to designate off-camera flash units as part of a flash group, then change the output setting of each group. The settings are transmitted to the speedlights through the little built-in flash on the camera, which sends control pulses invisible to the naked eye. This of course means that the camera and flash have to be able to “see” each other through line of sight, otherwise it doesn’t work.
Prior to traveling to a portrait shoot I decided to test my lighting setup and gear and put up two speedlights, umbrellas, and stands. I stood in as the model, and triggered the setup with a wireless remote. In every frame my eyes were closed. There is a considerable delay between the time the on-camera flash fires and when the speedlights pop. During that interval my eyes blinked every time. The solution was to set up a true wireless flash trigger; in this case I used a RadioPopper. You can use a PocketWizard or any of the discount setups available on eBay with good results. You models will blink after the main flash has fired. Commander mode is still a useful, but I’ll never use it for portrait work again.