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  #1  
Old 01-05-2009, 06:05 PM
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Default Off Camera Flash 101.....

So, with portraiture, eventually I am going to look at getting into off camera flash. Here's something that really puzzles me: You meter a scene and set your exposure, and have your flash set up and ready to go. Might be a stupid question, but how does your meter/camera "know" that you are going to add that extra light of the flash to the exposure? Wouldn't your image be totally blown out since you metered the scene without all that extra light? Someone, please...set me straight!
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Old 01-05-2009, 06:39 PM
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Couple things,
Off camera flash usually means a flash the is NOT built into the camera and and is a separate flash connected to the the "hot-shoe", the chrome thingy on top of your camera.

Now, when using a flash that is connected to the hot-shoe, your camera knows - or it should know

OK, if your shooting with free standing strobes that are NOT connected, your camera wont know.

There are other chimps that might be of more help then me, but this is what I know.

EDIT: HOLD ON, maybe I read your question wrong.
Yes, you would blow it out at that point, the key thing is that you shot with the flash first, - a test shot with the FLASH meter. (until you know more about flash) then re-set your exposure. If I am wrong, PLEASE someone correct me.
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Old 01-05-2009, 07:04 PM
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Thanks Todd...

If we're just chimping around at home we have plenty of time to adjust the exposure and even things out between camera and flash. But if, say, you're doing a wedding or a family shoot you don't have that kind of time! If you don't get it right the first time ya look like a goon!
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Last edited by Lensicon; 01-05-2009 at 07:08 PM.. Reason: sp
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Old 01-05-2009, 11:44 PM
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If you have the advantage of using off-camera flash, that flash and the camera aperture should be set for the correct exposure. The camera's flash can be set to a low level to trigger the external flash and perhaps to provide some fill-in light, but not enough to cause significant overexposure.
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Old 01-06-2009, 12:01 AM
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The camera I am using has a commander mode which will emit a small pulse of light to trigger the flash, which is of no concern in terms of the final exosure. I am not understanding how the image is not overexposed by the external flash if the light meter does not have that flash light to account for at the time of metering the scene. Sounds complicated, maybe I'm overthinking it all.
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Old 01-06-2009, 12:23 AM
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I think I remember being told to set the f-stop where I wanted it for the scene, the shutter speed for the flash sync, and set the flash for the output needed to match the f-stop chosen. I don't know if that's way off, though.
My best answer to you is to try some different setups and see what happens. Write every detail down (including distances between the different things). Also, try to replicate what you think you'd face at a wedding or reception and see what you get.
I usually use a flash meter, but I also tend to shoot still life type stuff, not people. Candid shots aren't going to work well if you have to set off the flash and check the reading before actually taking the shot.

Maybe there's stuff on this that will help: http://strobist.blogspot.com/2008/05...ting-dvds.html
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Old 02-05-2009, 08:53 AM
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just wanted to add my .02 here as I have in the PM's we have been exchanging...

To add some more info to John's original post, he is using a D80 with the commander mode. Cool thing about Nikon's with the commander mode (D80 and above) is they have the ability to fire an infinite amount of Nikon flash guns(sb-600, 800, and 900) wirelessly without the need to buy any transmitters or receivers. These are fired using the camera's on-board flash, which can be set to actually provide fill flash, or be set to have no effect in the final exposure of the image.

The camera "knows" you are adding this light by the very fast pulse as soon as you push your shutter button. This is actually read and transmitted by your Nikon and accounted for in the image.

Because of Nikon's CLS, you can set each off camera flash to certain levels, or have them be TTL. Your pick, you are the photographer
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