using d90 to trigger my sb 700 flash...should both flashes go off?

rampanthamster

rampanthamster

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hi all, i just got my first flash gun. Barely scratching the surface with it yet, but i was just wondering about using my d90's on board flash to trigger the flash gun. I've managed to do it, but the on board flash always goes off as well as the flash gun. Is there a way that only the flash gun will go off? Or does it depend on the light from the on board flash to trigger the flash gun?

Just wondering! :)
 
I'm also interested in..

When you use this feature, obviously the on-board flash fires, how does this work with the exposure?

I'd just want the flash from my off camera SBS not the on camera flash (trigger) in my picture.

So when you use this, are you getting 2 flashes in the picture or not
 
You can set the on board flash to fire at minimum power required to control the remote flash.

On the D90 this is set in e2 > Commander mode > Built in flash > --.

Page 188 of the D90 manual.
 
so when i'm in remote mode on the sb700...do i use the camera's exposure compensation to change the strength of the sb700 flash? Or does that only change the on board flash power? I'm a bit confused about how to control off camera flash at the moment. Are there any good tips?
 
I don't know the D90 and its controls - the manual should give a better idea of how to change flash exposure.

Basically, the on-board flash sends out a series of pre-flashes, a bit like morse code, to tell the receiving flash unit what it needs to do to contribute to the exposure; if you change the flash exposure in-camera then these pre-flashes control these changes.
 
rampanthamster said:
so when i'm in remote mode on the sb700...do i use the camera's exposure compensation to change the strength of the sb700 flash? Or does that only change the on board flash power? I'm a bit confused about how to control off camera flash at the moment. Are there any good tips?
Click to expand...

The camera will control the sb700 using iTTL when off the camera by communicating via the on board flash, just as it would if the sb700 was mounted on the hot shoe.
Any flash compensation you wish to dial in will also be communicated to the sb700.

The only thing to be aware of is that the camera assumes that the remote flash is the same distance from the subject as the camera. If you place it closer or further you will have to compensate.
 
The D90's pop-up can be switched off in commander mode, so that it only sends the (visible) command pre-flashes. The main flash is disabled, in theory, but it does still fires a very weak flash though this shouldn't show in the exposure. See handbook.

I don't understand Mike's last paragraph above - exposure is controlled by the camera, regardless of distance.
 
I have a D90 and this was the most confusing thing I ran into because the manual seems to imply that you turn the flash off, yet it still fires. Don't be worried. As has already been mentioned these are preflashes designed to sync up the off camera flashes. When the actual shutter trips the on camera flash is not active
 
whittyp said:
I have a D90 and this was the most confusing thing I ran into because the manual seems to imply that you turn the flash off, yet it still fires. Don't be worried. As has already been mentioned these are preflashes designed to sync up the off camera flashes. When the actual shutter trips the on camera flash is not active
Click to expand...

Is this 100%?

When i was playing with the CLS on my sbs600,

i had my camera looking at a mirror with the flash up, and my sbs behind me, i got the beeps from the SBS showing that it had fired but in the shot you could see my pop up flash was illuminated, obviously giving flash in the exposure?
 
Carbonangel said:
Is this 100%?

When i was playing with the CLS on my sbs600,

i had my camera looking at a mirror with the flash up, and my sbs behind me, i got the beeps from the SBS showing that it had fired but in the shot you could see my pop up flash was illuminated, obviously giving flash in the exposure?
Click to expand...

hmmn, i just did the same thing and yes - you can see the flash in the mirror. I'm wondering if this has something to do with the shutter speed or something. I really don't know anything about flash yet...

can someone recommend a good link that really explains in easy to follow detail how it all works? :)
 
rampanthamster said:
hmmn, i just did the same thing and yes - you can see the flash in the mirror. I'm wondering if this has something to do with the shutter speed or something. I really don't know anything about flash yet...

can someone recommend a good link that really explains in easy to follow detail how it all works? :)
Click to expand...

The main flash actually does fire even when it's theoretically disabled, Canons do it too, but it's at extremely low power - less than the normal minimum output. It doesn't affect the exposure unless you're very close at low f/number, and even then hardly noticeable.

If it's a problem, cover the pop-up with a couple of red cellophane wrappers from a box of Quality Street. That dims the light, but the slaves are still sensitive to the red and remi-IR from the commander.
 
Nikon sell a widget to do the same job as the quality street wrappers if you wish to spend your hard earned. I've also found an old 35 mm negative works well if you have one lying around
 
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