Optical triggering

[db-images]

Can anyone solve this problem for me:

I have a studio fitted with 2 x pro-line heads in softboxes and 2 x pro-line slaves with shoot through brollies. I shoot manual with a synch cord fitted to one of the heads. The other head and the 2 x slaves take their cue from the light I'm tethered to. This all works fine, but I find that because the studio is quite compact, the flash heads are too bright in some set-ups.

So, I also have an st-e2 trigger which I use in conjunction with my 2 x 430ex flashes for more controlled strobist type work. However, I had tried to flood-out a white backdrop by using the pro-line heads as back-lights, hoping they would take their cue from my flashlights, but it doesn't work; the studio heads do fire, but they seem not to synch and, on review, the background is left grey.

Can anyone 'enlighten' me as to why this is?

I should mention that I am shooting with the camera on manual and both 430ex's set on slave/manual - no ettl setting which I know give an initial test burst. Also, I have just purchased two Hama slave unit hot shoe contacts which I want to attach to a couple of older, fixed-output camera flashes that I have and I'm now not sure whether all the flashes will synch. (Still waiting for them to arrive from Amazon).

Thanks in advance.

 

[Garry Edwards]

Use neutral density gels over your studio flash heads to reduce the output. I have loads of different ones but the ones I use all the time are 0.9 (3 stops).

I know nothing about Canon but I'm wondering whether your shutter speed is too high to synch reliably with your studio flash heads. It doesn't follow that just because your camera will synch at (say) 1/250th with hotshoe flashes that it will also synch at that speed with studio heads. I know that both electricity and light travel at 186,000 miles per second but there's a delay caused by the circuity - so try is for yourself at say 1/60th. Testing sometimes beats theory.

 

[db-images]

Thanks for the response, Garry.

I tried this after reading your post; went from 1sec - to 1/250th, but the output remained the same.

The studio lights are firing, but they're either too early or too late, but definitely not synch'd. It's almost as though the flash is sending a test burst before the main light. But both 430ex's are set on full manual.

I don't understand it.

 

[swanseamale47]

Are the 430s firing an IR test first? some flashes do this to measure the distance, try covering up the ir flash part with foil or tape and see if it helps. Wayne

 

[db-images]

Garry / Wayne

Thanks for the response.

Wayne, I think you are on the right track!

I posted the same question in flickr's Canon wireless group and I received an url from one of the lads there which sounds like the right explanation.

Apparently, the st-e2 sends out an instruction to the 430ex's instructing them to get ready to fire!!!! This is picked up by the studio heads as a fire instruction so, by the time the st-e2 sends its own 'fire' instruction to the 430's and the shutter opens, the studio lights have already fired!

His solution is to insert a piece of paper over the four outside contacts on the st-en contact platform, which will disable the signal. However, this might also work as you suggested - wayne - by covering one of the signal windows.

Too late to get back to the studio tonight, but I'll try both options tomorrow and get back to you with the results.

For your own info, the explanation can be found here. www.velvetlens.com/PhotoTips/Wireless/WirelessFAQ.htm#Q15