Inconsistant Flash Output

3 replies [Last post]
Joined: May 26 1999

I'm using Bowens Gemini professional flash heads to produce lighting for a series of 'macro' timelapses.

Opinions on how I can get consistent output with the flash equipment (or similar) would be appreciated. As you can see from this clip, the lighting flickers due to what appears to be power differences in the flash.

The environment is carefully controlled, with no changes in temperature or extraneous lighting whatsoever, so it has to be differences in the flash that is causing the unwanted flicker.

Regular lighting would not be feasible (even though I have tons of lighting equipment) as for one of the upcoming projects, I need to leave the camera running at approx 1 frame per hour for about 2 months. Running 1kw plus of lighting for that duration would be extremely expensive.

Any ideas or comments appreciated?

Alan Roberts
Alan Roberts's picture
Joined: May 3 1999

That's a significant change of lighting. I remember, from the days when we were setting up Planet earth, that the stop-action guru had immense problems getting consistent lighting. I don't know hoe it all ended up, but I think there was a huge amount of post work, trimming exposures.

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Joined: Jan 28 2004

Interesting problem, I have a set of Bowens Geminis (500s and 750s) and I've noticed a slight difference in exposures, no big deal with photos but certainly would be with your job.

I can only imagine that the capacitors charge slightly differently each time, maybe temperature? Have you asked Bowens?

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Gavin Gration
Joined: Jul 29 1999

I suspect Claire is right. The electronics may not have been designed to be 'that good'. If you can sort the exposure so that the flash is always firing at full whack it might reduce the potential for variation a bit.

Ideas? Well.....

Can you set your rig to trigger a dummy flash a few seconds prior to the desired exposure time so that the actual exposure is taken with a freshly charged flash?

My 'simple' way to do this would be to use a 2nd camera body set on the same time-lapse duration but started a minute or so prior to the real camera.

Hope this helps.