D700 flash commander mode affecting exposure

Pindy

This is not good. 1/60s @ f4, 200 ISO

Picture I just took of a bag with my SB900 OFF and the commander pop-up down:




Now this is with the SB900 STILL OFF and the pop-up in the upright position and the internal flash set to "——" in the Commander Mode menu:




I have the camera set to Tungsten, hence the blue cast. What's going on?

angevin1

Hey P,
'
It will as long as your f number is low. The Onboard flash is still sending a signal in "----" setting. So try a higher f number and see if it disappears.
Additionally, the photo appears to be fairly close in, so taking a step or three back should change it's effect dramatically.

Pindy

I'll try that, but still, shouldn't the commander bursts be synced as to not interfere?

mutti_wilson

Pindy wrote:

I'll try that, but still, shouldn't the commander bursts be synced as to not interfere?

I believe all it does is lower the output to next to nothing. The flash does not fire at any different time than if you are using it for a true flash. If you put an IR filter over the flash you can fire it at full power and it will still trigger the remote flash. Try shielding it with your hand in a way that allows some light to reach the flash.

angevin1

Pindy wrote:

I'll try that, but still, shouldn't the commander bursts be synced as to not interfere?

I don't see how...if in commander mode and we use ttl, we have to float that info out on the IR signal...so it stands to reason, for me, that this info would be in sync with the flash component...be interesting to see/read the data supporting this. I did what Mutti suggested for a long time due to this problem..sometimes holding my hand up, sometimes cutting a peice of cardboard out to direct or scoop the onboard flash "----" towards the remotely set up flash.

Pindy

Okay, that's interesting. I would have thought that it could send the pulse before opening the shutter, but maybe all the little blinks happen during. Glad nothing's wrong, but I can see why the SU800 is a good thing to have.

angevin1

Pindy wrote:

Okay, that's interesting. I would have thought that it could send the pulse before opening the shutter, but maybe all the little blinks happen during. Glad nothing's wrong, but I can see why the SU800 is a good thing to have.

I would tend to agree with your statment about the SU800, but why not try a higher f number and report back? And try it in a simulated portrait setting: 10 or 12 feet distant from subject, higher f number included.

jrmyrnsm

You could always get a Nikon SG-31R which is designed for the very purpose of blocking the onboard flash when using it as a commander. I've got one and it seems to work pretty well.

Wil Davis

Pindy wrote:

Okay, that's interesting. I would have thought that it could send the pulse before opening the shutter, but maybe all the little blinks happen during. Glad nothing's wrong, but I can see why the SU800 is a good thing to have.

That's exactly how CLS & iTTL are described in all the Nikon literature I've read. To quote Mike Hagen's "The Nikon Creative Lighting System":

Preflash Sequence:
1. Press shutter release
2. Speedlight sends preflash
3. Matrix meter reads reflected light
4. Camera makes new output calculation
5. Shutter opens
6. Speedlight fires "real" flash
7. Shutter closes


Even when the Commander is in "--" (=Off) mode, the master flash will still send out pre-flashes even though the unit itself doesn't fire.

BTW - The SG-3IR was mentioned in a recent (about 6 months ago) thread where someone had found the SG-3IR was very hard to find, so they made their own simply by taping a small piece of exposed film (film? what's that???) over the on-camera flash. I think the subject was about using the on-camera flash to get highlights in the eyes when taking portraits.

HTH -
- Wil

kundalini

This may help or add to the confusion. I've noticed similar results, but I was usually doing closeup or macro shots. I too was getting some affect with the pop-up even though it was set to (--). My workaround was to use a white business card, my hand, or anything handy.

VERY unscientific test. Aperture Priority f/3.5, ISO800

Pop-up Flash OFF

Pop-Up ON (one or more Groups set ON)




Pop-Up ON (all Groups set OFF)

My conclusion...... if I'm not using flash, I don't raise the pop-up.

One tip I can offer with off camera flash using CLS outside. Everyone says the flash sensor "has" to be in direct line-of-sight of the pop-up for them to trigger. Nope. I've used folded aluminum foil and even the case of one of my filters to bounce the pre-flash backwards to the off-camera flashes at least three feet BEHIND me. I haven't tested any further distances because I haven't needed to, but just food for thought.


This is one of the shots I was refering to. Soft box camera right, shoot through camera right. Both very much behind me.




My 2¢.

Qarik

okay I just noticed it too on my d700. the commander set at -- does effect the exposure. In my case it left a shadow. I used my hand to block it and it worked okay. I don't recall this being much of an issue with the D90 or D200 but I could be wrong.

Art Scott

SG-3IR Filter
Does any one know how much if any distance this filter decreases the pop up flashes working distance in commander mode.....I will have it set to ("- - ") but it still fires my optical slaved flashes with the dang pre-flashes........