On camera flash does contribute to exposure...

LilyJack

Ok, don't start rolling your eyes ...I can see you doing it.Granted, to be honest, I am somewhat new to using the off-camera flash. And I know, I know, on-camera flash is not suppose to contribute to exposure when camera is in commander mode. There, I saw you roll those eyes again. I've read and read, and I know I'm missing something somewhere since everywhere and everyone says it doesn't contribute but...Here's the rub: Taking portraits. Fairly close to subject 3-4 feet. Using D300, 50mm f1.4, and SB-600 flash off camera with shoot through umbrella. Pop up flash is up and camera is in commander mode with Flash set to "--". I take the pic: That pic has noticeable straight-on flash shadow on wall behind subject with straight-on catch light in eyes. I throw a piece of cardboard in front of the on-camera flash, and viola! no flash shadow behind subject or dead-center catchlight.... Hmm, doesn't fly with all that I've read in tutorials, blogs, dgrin, etc...I know I can move subject from wall but I also know I shouldn't have to.

Thoughts? Thanks in advance for not totally roasting me here if I've missed something simple but I really, really tried to cover all bases before posting...
Kate

ziggy53

I'll bump this a bit to see if a Nikon shooter can help first. If none respond in a couple of days, I'll try to see if I can help.

pathfinder

Hi Ziggy, I was hoping someone would answer this, as I am not a Nikon flash shooter.

Nonetheless, the answer is that on-camera flash can effect exposure or cast shadows IF it is bright enough. It all depends on the ratio of light from the on camera flash to the off camera flash, doesn't it?

And yes, standing your subject directly in front of a wall, and having the camera with flash close to the subject, and hence close to the wall, is an ideal way to maximize the light/shadow from the on camera flash unit, too.

LilyJack

Thanks for the responses. Pathfinder - from the lit everywhere (official Nikon sources too). Setting the on camera flash to "--" should cause the "built in flash to turn off during exposure. By choosing this, the built in flash will not fire to contribute to exposure." Wouldn't be so confusing/annoying if all the lit wasn't so adamant that it doesn't contribute. Flash compensation changes both built in and off camera flash so that doesn't help either since I still want full power from off -c flash.

Been doing more testing and in the end, it's proximity to subject that is key. It seems the lit should really state that but that is not what I've found.... Logically (yes, I'm part Vulcan) it makes sense... Just wish I could still get into those tight shots without having to block the pop up...

If any finds more info, I'd still be interested in thoughts and personal findings...
Muchas gracias!

pathfinder

If the on camera pop up flash is the issue for you, why not just plug in a 3-5 meter PC flash cord to connect your off camera flash to your camera body, and use manual control of the flash exposure. That will eliminate the shadow and frontal lighting from your on camera pop up unit completely.

I suspect your are shooting quite mobile and extemporaneous, and thus not enthused about a wire and its limitations maybe??

Sounds like the Canon radio controlled flash system is what you are looking for......... No light to off camera flash, just a non-light radio beam.

Pocket Wizard has offered radio triggers with iTTL control for off camera flash for Nikon for several years, although the reports on its absolute success seem slightly muted.

The Canon radio system gets pretty high reviews from users, although I have not used it yet myself. It is on my shopping list this fall. Its price has come down some since the initial introduction.

I do not understand why your on camera pop up flash is lighting if Nikon says it will not light up, but the system does use the light beam to modulate the control information from the commander to the flash, at least in the older Canon IR wireless system. The nice thing is the Canon radio system makes all those issues disappear out to a radius of ~100 feet.

doyle

Agreed, a decent trigger system will fix this however, in using an off camera flash for very close shots, I have used my hand to block the on camera flash from hitting the subject while still hitting the external flash to trigger it. I know what the literature says, but any way you slice it, the flash is putting out additional light. It may not be much, but it's something. Obviously the darker the subject environment, the more pronounced the effect of the on camera flash.

pathfinder

Great suggestion Doyle, simple, handy and easy to do!

I actually forgot, but I used to bounce the IR signal from Canon's wireless flash controller off my hand at times to get further off camera reach like you described. Simpler is easier!

time2smile

Even thou the OCF is not suppose to contribute, I found on the D90 and D7000 that with the right conditions, very close or amount of ambient light at the location, it does. That's why Nikon has the su800. I agree with all above, either an extension cord like the sc29, or try a wireless flash system. Good Luck......