Using onboard flash as commander for sb800

ssquiffy

Senior Member
If I set camera up to use the on board flash to trigger an SB800 off camera, the following happens......even though I set it up so the on camera flash doesn't fire (2 --) it still seems to fire a flash as well as the SB800 firing....is it the actual light that triggers the slave flash???
 

ssquiffy

Senior Member
Thanks @nickt, that answered my question perfectly.... Although the built in flash does flash it is actually before the shutter opens, even though it doesn't seem like it to the human eye
 

nickt

Senior Member
Thanks @nickt, that answered my question perfectly.... Although the built in flash does flash it is actually before the shutter opens, even though it doesn't seem like it to the human eye

Ok, now I am going to complicate it, lol. Nikon makes this thing:

Nikon SG-3IR IR Panel for Built-In Flash 4905 B&H Photo Video

I never really though about it real hard, but now I'm not sure why this thing is needed if all preflash is before the shutter. Maybe subject distraction? But reading the first few reviews on that site, I see someone saying they see the preflash reflecting in a mirror. Maybe @WayneF can explain when this device might be needed.
 

ssquiffy

Senior Member
I am currently having this discussion with a pro friend of mine, he doesn't get it. The way I understand it is the onboard flashes just before shutter opens, the flash of light is the trigger to set the slave (off camera speedlite), the slave them operates when the shutter is actually open......is my understanding correct??
Also if the pre flash is so close to the actual flash firing (so close together it can't be detected as a difference with the human eye) surely it must have a influence on the final image??
 

WayneF

Senior Member
The SG-3IR filter serves two helpful purposes.

One, all that commander flashing (in the subjects face when they are looking at the camera) usually causes human subjects to blink, with such timing that all you get is pictures of the subject blinking. The filter hides the visible light that the subject sees, but still allows the infrared light to pass, which still controls the remote flashes. It prevents the blinking.
The SU-800 commander has the red filter built in.

Or... cameras with Commander also have the FV Lock feature, which probably works even better about preventing the blinking, when you get used to it. It will also prevent any blinking due to the remote preflash itself.

See Using the Nikon CLS Remote Wireless Flash System - Part 2

Two, when the commander is done flashing commands, then the shutter opens and the commander flashes one time time to tell the remotes "OK, everybody fire NOW". If at close macro distances, or if at a few feet at wide aperture like f/2, this flash signal can be visible in the picture of reflective things (like a reflection catch light). The filter hides that too. It is a weak signal, but up close or wide aperture, it can have small effect.

See Using the Nikon CLS Remote Wireless Flash System - Part 2 (same page)
 
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WayneF

Senior Member
I am currently having this discussion with a pro friend of mine, he doesn't get it. The way I understand it is the onboard flashes just before shutter opens, the flash of light is the trigger to set the slave (off camera speedlite), the slave them operates when the shutter is actually open......is my understanding correct??
Also if the pre flash is so close to the actual flash firing (so close together it can't be detected as a difference with the human eye) surely it must have a influence on the final image??

The TTL preflash occurs before the shutter opens. Then the camera meters the preflash, and sets power level in the flash, and then opens the shutter and triggers the flash. Preflash is very close to the final flash, humans don't realize it occurred, but preflash occurs before the shutter opens.

Commander signal flashing is also before shutter opens. Some of the commands are to request the preflash, individually from each remote flash. Then the commands set power levels, then the shutter opens, and the flashes are triggered. There is a lot of flashing involved.
 
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ssquiffy

Senior Member
Thanks @WayneF, so although handy to have the option, I guess that's the reason most people just use wired or wireless triggers so there is no chance of the commander influencing the light in the final image??
 

WayneF

Senior Member
Thanks @WayneF, so although handy to have the option, I guess that's the reason most people just use wired or wireless triggers so there is no chance of the commander influencing the light in the final image??

I'm sure opinions are varied, but I'd say not that reason (although radio would solve it of course). The radio triggers are normally preferred when the Commander optical range is deemed insufficient. The commander normally works fine like in the living room, very little issues. But it can be problem at abnormal distances, or when obstacles are involved, or outside in bright sun. Radio triggers work around those issues, but the inexpensive radio triggers cannot do TTL. :) Also, the camera commander can only individually control two remote flashes (but again, it can do TTL, and lighting ratios, etc).

The reflection is normally very little problem, except at very close distances (macro) or at very wide aperture. And then typically only in reflective subjects (like chrome balls). I can't say it has ever bothered me, in other normal shooting. I have to hunt for it to be problem. :) The SG-3IR filter is a good $12 fix.
 

ssquiffy

Senior Member
Ok so now with all the worry of the on board flash influencing the final image, and the possibility of buying a gizmo to cover the on board flash I'm thinking why not just buy a cheap set of triggers for less than £20???
 

WayneF

Senior Member
Ok so now with all the worry of the on board flash influencing the final image, and the possibility of buying a gizmo to cover the on board flash I'm thinking why not just buy a cheap set of triggers for less than £20???

That will work, perhaps even triggering better in a few situations, but it will NOT include TTL operation. Strictly manual flash mode.

The commander is really awesome for a couple of TTL flashes. Just throw them out there, set a ratio, and have at it, snap away. Get your picture and be gone very quickly. Effortless setup.

I suppose you realize how manual flashes would change that? We can use a handheld flash meter to set manual flashes, but even that is not quick.
 

WayneF

Senior Member
Yes, I am saying that cheap radio triggers are incapable of doing TTL. TTL involves communication between camera and flash, to request preflash, to meter it, to set TTL power level in the remote flash, and then finally, to trigger the flash. Cheap radio triggers can only do this one last final step.

For manual flashes, you will have to determine power level and set power level yourself, manually, before you return to the camera shutter button.

There are radio "systems" that can do TTL. Not inexpensive.
 

Daz

Senior Member
I dont see why everyone is so obsessed about having TTL, TTL is the most useless feature I have ever found and it is like an Auto mode for flash ...

What happens when you are out in direct sunlight and want to add some fill to your subject and you are metering for the sky ... You get very little flash, learn how to manually set flashes and it is a heck of a lot easier.

If you are in a studio environment getting the correct exposure with Manual flashes can be done within 3 photos if you are not using a light meter when you are used to setting manual.

I was out at a shoot with a friend of mine tonight (We were shooting a jujitsu artist and a musician at the same place but in 2 different areas so we could work individually) he insists on using his SB-800's and the commander mode on the camera, it took him at least 20 mins to set it up, by that time I had got most of the way through my shoot with the Jujitsu artist and I use Yongnuo 560 Mark 4's (4 of them) and the 560-TX controller that sits on top of the camera and I was trying to make my shoot take longer and chatting a lot to try and give him time to catch up.
 
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