Commander Mode: Pre-flash light spilling into final exposure.

J

justice91423

New member
When I am using my Nikon D-90 in commander mode, with the built-in flash set to not be used (--) I still get some light from it in the final image.

I created the image below to illustrate what I am seeing. Note that there is no change in the exposure settings or the available light. And there are no other flashes present.


The first image is with no flash at all (built-in flash not popped up)

The 2nd image is in commander mode with the built in set to not be used (--)

The 3rd is in commander mode with the built-in set to it's lowest setting 1/128


Does anyone else get these results?

Is there any chance this is user error?


20140403-DSC_5247.jpg
 
M

Moab Man

Senior Member
To avoid the camera flash altogether there are radio triggers that can be purchased. However, I have not used radio triggers personally.
 
J

justice91423

New member
Wow! that's a bummer. I always assumed that the main flash was timed to occur after a pre-flash from the commander. That is a big blow to use usefulness of commander mode.

I really appreciate the info though. I spoke to a Nikon rep on the phone and he seemed to think the camera was malfunctioning and wanted me to send it in for repair.
 
W

WayneF

Senior Member
justice91423 said:
When I am using my Nikon D-90 in commander mode, with the built-in flash set to not be used (--) I still get some light from it in the final image.

I created the image below to illustrate what I am seeing. Note that there is no change in the exposure settings or the available light. And there are no other flashes present.


The first image is with no flash at all (built-in flash not popped up)

The 2nd image is in commander mode with the built in set to not be used (--)

The 3rd is in commander mode with the built-in set to it's lowest setting 1/128


Does anyone else get these results?

Is there any chance this is user error?
Click to expand...


Well frankly, objecting that 1/128 power interferes with your flash pictures sounds like your expectations might be too low. :) Just saying, if your remote flash needed to be up near 1/4 power or something, it would surely entirely cover this up.

Setting the mode to "--" does turn the internal flash off. Totally off, as a flash. However, it is also the Commander, so it will still flash commands BEFORE the shutter opens, but then it will not contribute to the picture lighting after the shutter opens.

Except, after shutter opens, it still has to flash a signal to the remotes "OK, Everybody flash NOW!". Your test result shows this is less bright than when you told it to contribute with 1/128 power, which added to it.

But... there is an optional $12 Nikon SG-3IR panel (placed in the hot shoe, and from there, it can cover the internal flash) which blocks the visible light from the flash, and still allows the infrared component (sufficient for the commands.) If you cannot use a brighter flash for your pictures, then that should help do the job.

See Using the Nikon CLS Remote Wireless Flash System for more about this slave trigger signal and the SG-3IR panel.
 
F

FastGlass

Senior Member
One of the biggest problems when using an on camera flash as commander is that you will not eliminate reflections. The images you show. The light is mostly reflections. Simply put you hand between the flash and the subject while still allowing the other flash to see it.
 
J

justice91423

New member
WayneF said:
But... there is an optional $12 Nikon SG-3IR panel (placed in the hot shoe, and from there, it can cover the internal flash) which blocks the visible light from the flash, and still allows the infrared component (sufficient for the commands.) If you cannot use a brighter flash for your pictures, then that should help do the job.

See Using the Nikon CLS Remote Wireless Flash System for more about this slave trigger signal and the SG-3IR panel.
Click to expand...

I was just looking at that little dodad. seems like a good fix. Thanks
 
J

justice91423

New member
FastGlass said:
One of the biggest problems when using an on camera flash as commander is that you will not eliminate reflections. The images you show. The light is mostly reflections. Simply put you hand between the flash and the subject while still allowing the other flash to see it.
Click to expand...


Wow! yeah that is a simple (and should have been obvious) fix. Thanks
 
Y

yauman

Senior Member
justice91423 said:
Wow! that's a bummer. I always assumed that the main flash was timed to occur after a pre-flash from the commander. That is a big blow to use usefulness of commander mode.

I really appreciate the info though. I spoke to a Nikon rep on the phone and he seemed to think the camera was malfunctioning and wanted me to send it in for repair.
Click to expand...

The camera communicates with the remote flash via pulses of very low power flashes - as sequence of "dot" and "dashes" like Morse code. That communication string tells the remote flash what settings to use - ie power level, head zoom position etc. Then when it's time to tell it to go off, it has to send another "GO signal" via another short burst of low level flash.

Now, the reason the pre-flash "setting" communications has to be different from the final "Go" signal is that it give you the option to "Flash Lock" ie, send the preflash separately to tell the remote flash to lock in the settings - then when you take the picture, it just need to send the "go" signal without being preceded by a pre-flash sequence. You can program one of the buttons to be the FV button -it's a good option especially when you are photographing subjects who are sensitive and quick blinkers - blinking at the preflash, caught with their eyes close when the main flash goes off. I always use the Flash Lock option when shooting models - just one pre-flash during setup and then shot away without any more pre-flashing. When you use Flash Lock, the locked settings stays until you do another flash lock so subsequent firing is just a much shorter firing signal rather than a longer string of pre-flash instructions.

I always wonder why Nikon (and others) don't use RF to communicate rather than light pulses. With modern integrated chip technology, it's so simple, cheap and easy to just embed and RF comm chip in the camera and the flash!
 
R

rocketman122

Senior Member
I use slaved flashes all the time in weddings. you can buy a great set (1 transmitter/1 receiver) that will only cost $24 for a set, shipped on ebay. gives much more flexibility. doesnt have to be line of sight. can even be in another room. no one else can trigger them. versatility and you can be much more creative. sync to 1/320. ttl pass through hot shoe. locking pin and wheel.

commlite G430. if you get the H550 transmitter you can sync till 1/8000 if you need to.
 
Top