300D Slave Sync Problem

[PhotosGuy]

I was trying a set-up to copy slides:

CAM____Diffusion material ____ >[] Slaves (1 or 2)

I’m in M mode & tried this at shutter speeds from 1/200 down ‘till I was getting exposure from ambient light. The strobes, using Vivitar SL-2’s to fire them from the cam strobe bounced off the ceiling, aren’t synching. I’ve tried them independently with 2 different slave triggers, so it doesn’t seem to be a mechanical problem with them.

I’m using a manual Nikkor lens & wondered if there was a problem caused by that, but if I use only the cam strobe aimed at the diffusion screen, I do get synch.

I’m out of ideas. Got any? http://www.photography-on-the.net/forum/images/smilies/icon_confused.gif

[mf_blues]

Hi

If you're using the Canons flash to trigger the slaves then it is because the canon uses a preflash which triggers the strobes too early, you can't see it but it's there as I found out recently. I use a PC sync cord on a hotshoe adapter with my 300D, you have to be carefull of the trigger voltage, my strobe returns 9volts and so far seems fine with the 300D. You can get a Wein Safesync Hotshoe which stops the voltage exceeding 6volts.

If you are triggering the slaves with another flash set the unit to manual just in case it uses preflash, this should then resolve the problem.

Hope this helps

Cheers

Mart.:)

[PhotosGuy]

You're right - can't see it at all! There's no way to turn pre-flash off?
I've had a hotshoe adaptor on my list to get, so I will, but I wanted to use this NOW! ;-)
Thank's for the help.

[mf_blues]

Unfortunately there's no way to turn it off, one work around though. Press and hold the FEL button this will fire the preflash, let your strobes charge up again then take the shot. Make sure you keep the FEL button held before taking the shot.

Hope that works.

Cheers

Mart.

[PhotosGuy]

Thank's again. I'll give that a try. ;-D

[PhotosGuy]

YAY! That works great! + I can do it NOW! (I've had these delayed gratification issues all my life! Why change now?)
BIG thanks again! http://www.photography-on-the.net/forum/images/smilies/icon_biggrin.gifhttp://www.photography-on-the.net/forum/images/smilies/icon_biggrin.gifhttp://www.photography-on-the.net/forum/images/smilies/icon_biggrin.gif

[mf_blues]

Glad I could help, nice one.:D

cheers

Mart.:)

PS. Also thanks to NHL of Stevesforums, he was the guy who pointed me in the right direction. Hope this doesn't break any rules mentioning another forum an all.:o

[PhotosGuy]

Update: Actually it worked better than great. Since I was bouncing the on-cam flash off the ceiling with a piece of tin foil, I found that the weaker pre-flash could be shielded enough that it wasn't strong enough to trip the main flashes, & the stronger actual cam-flash would set off the slaves.
Here's a HQ JPEG & an unsharpened 150% crop of the 1st copy. Now it's just a matter of moving things around to get a flat light field @ f-16. ;)
Is anyone interested in a pic of the final set-up?

[scottbergerphoto]

You can purchase Wein Digital Ultra Slaves that ignore the preflash and attach one to each strobe.
scott