Paul C. Buff, Inc. Technical Forum

Here's an odd situation that I hope someone can figure out.

I have two CST's. I had an idea to create "multiple exposures" by releasing the shutter with a long exposure (2-5 seconds) then depressing the test button on the CST to fire the strobes additional times. I tried this out with the CST on my hot shoe and everything worked as I thought it would.

I then had a few other people try it out and some people had a problem. The CST would fire based on the shutter release but the test button would not trigger while the shutter was open. After the shutter closed, the test button would trigger with the CST on the hot shoe.

I concluded that certain makes/models of camera bodes had some sort of issue.

Then, I tried my first example again with my camera body and I got different results. In this second trial, the test button wouldn't trigger while the shutter was open. I swapped with my second CST and got the same behavior - the test button would not trigger while the shutter was open.

Can anyone explain this behavior?

Tim

on my camera, Sony A700, the same happens. hotshoe mounted CST, open shutter for 5 seconds, flash fires upon initial shutter actuation, same CST will not respond to button presses while shutter is open. I dont know the inner workings of cameras intimately, but it seems the hot shoe (and likely PC connections) will remain closed for the duration of the exposure. I would not be surprised if it had something to do with FP flash, but that is irrelevent and speculation. As long as the circuit is closed, the CST will not respond to additional input (however, on exposures longer than about 9 seconds or so, the CST will fire every ~9 seconds) .

However, i would not recommend this method if it did work, particularly if you already have 2 CST's, as it could introduce camera shake at such long exposures. What I would do instead is use the second CST for the additional pops, which does work.

Since this is such a long exposure, why not just keep the CST in your hand and hit the button 2x after the exposure starts? I know it does not answer your question, but might offer a very simple answer until you have a technical solution.

I figured it out. The CST can be triggered with the test button while on the hot shoe if rear curtain sync is used.

What model camera are you using?

RMS

Nikon D700