I have my 20d Camera, Light Stand, Umbrella, Quntaray Flash, Optical Slave Flash. I have a question about the Optical Slave.
Lets stay i have the flash on my Stand, shooting through the Umbrella How can I get my flash to go off, without flashing my on Camera pop up flash?

Hello.

"The idea of an optical slave is that the slave flash is triggered when it detects the light burst from the master flash. The slave contains a photodetector for this purpose."

There isn't a way to trigger the optical slave without a master flash going off. You have a couple of options.

1. Dial the on camera flash down so that its effect is minimal on your exposure.
2. Get a wireless transmitter and receiver in order to trigger your off camera flash.
3. Use a sync cord which can be cumbersome

Bryan N.

kool I didnt think about dialing the on camera flash down. I can work with that. Thanks for the reply.

The other thing you can do is place your hand in front of your on-camera flash and "steer" the light toward the flash on your stand. This keeps the on-camera flash off the subject (which is what you're trying to avoid) yet still fires the other flash w/ the optical slave.

I've done this w/ a D70. Takes a little practice but can be very effective.

--mg

1st Annual Florida Strobist Meet

I saw the post that there is a Stobist meet soon. I am going to PM you of what it consist. I am interested.

This may not work properly with your setup unless you have an optical slave that ignores the preflash from the 20D. If it does then like the others said you can dial down your flash and they also make a little panel that you can put in front of it to soften it further if needed. I think it's from Lumiquest.

lastnight i was playing around with it. In the Custom Fuction you can turn off the preflash on the on camera Flash. Im just playing around with it. anyone has a video on direct site i can learn from.

You can turn the flash off and you can turn the focus assist off but I wasn't aware of any way to turn the preflash off. The on camera flash doesn't do manual, only TTL.