I am testing with a Nikon SB910 as remote flash and the camera is Nikon D-810 and in settings I have put it in Commander mode.
It does fire the flash but the zoom on flash is not reading from the zoom on the camera lens.
Is this how it works in this setup? or I am doing something wrong?
It does read the zoom when I directly install the flash on the camera.
And is it just zoom? or now it is really just like a manual flash and I have to setup the power too?
A flash on the camera's hot shoe is in a known location relative to the film plane. From that, it's easy to calculate where to place the zoom head so the light covers the area the camera actually sees. The extra energy spent lighting the area seen by a 24mm lens when the actual focal length is 85mm would simply be wasted, and that saps the batteries and increases recycle time.
For the remote flashes, the focal length doesn't have any meaning because the only part of the system with any idea where they're placed and how they're being used is the photographer. Speedlights with zoomable heads give you the option of adjusting the focal length manually in remote mode. That can be used to limit where light is thrown if you have enough information on hand to come up with the correct setting.
No. With CLS, this control is not possible (Canon's wireless system for flash can zoom flashes remotely--however, Canon's wireless flash can't do 2nd curtain sync while Nikon's can).
However, if you use the Yongnuo YN-622N triggers with a YN-622N-TX transmitter, or Phottix Odins, you will have remote zoom control over your flashes, but it may only be by group (i.e., all flashes in a group have to use the same zoom setting). PocketWizard and RadioPopper TTL triggers cannot do this.
If you use radio triggers instead of your pop-up flash to master the remote flash, you'll regain FP/HSS, and you won't have to worry about range or line of sight issues. But radio interference now becomes a possible concern. :)
No, the transmission of zoom information is not done, because it is pointless. As Birfl said, the flashes are likely at a very different distance than the lens, and any lens zoom value would be totally meaningless to the flash (if it is not on the hot shoe). Main flash up close (5 feet), camera maybe 8 feet for perspective, and fill light behind the camera (10 feet). When their distance is different, the same zoom would cover very different area sizes. Any effort to make them the same zoom is pointless. The default will be wide (24mm), but you can always zoom each flash manually.
