Exposure dilema

Jake Iesu · May 26, 2009

Hey.

I have a rock concert shoot coming up in a few days and would like some advice on setting exposures on an unmanned camera.

The concept is to have a stills camera mounted from the lighting rig shooting wides at an interval of about 14secs in order to make a time lapse of the entire performance.

From what the director has told me the light show will start off rather low key for a few songs alot of backlighting through fog and they will gradually introduce OLED displays across the entire stage and build up the lighting slowly until they hit one of their signatures songs at which point the Light show basically explodes with the intent of the audience having to cover their eyes.

How on earth do i achieve an accurate exposure on something that can potentially change 10 stops? I have thought of using a auto exposure on the camera but i fear the Camera will take an auto reading off a light or OLED screen and close my iris down so I have no other details or vica versa.

Any suggestions?

Simon Wyss · May 26, 2009

If it is possible for the light magician to let the set shine at half value you may read on that, an average of lowest and full power. That value I'd leave throughout the show.

David Mullen ASC · May 26, 2009

I know it would be a pain to edit, but since you have such long intervals between photos, why not bracket the exposures? Have the camera take three in a row for each interval and then pick the frame with the best exposure? Of course, it creates a lot of editing work in post.

Chris Keth · May 26, 2009

I know it would be a pain to edit, but since you have such long intervals between photos, why not bracket the exposures? Have the camera take three in a row for each interval and then pick the frame with the best exposure? Of course, it creates a lot of editing work in post.

I don't know all of the options of your camera, but perhaps you can create a file naming scheme that would help. Something along the lines of having it bracket and append "A" to the darkest frame,"B" to the middle exposure, and "C" to the hottest frames. That would make it pretty simple to compile 3 sequences: a dark sequence, a middle sequence, and a hot sequence of stills. Then you could tune the exposure throughout the timelapse by layering all three and adjusting the opacity on keyframes.

Edited May 26, 2009 by Chris Keth

Jake Iesu · May 26, 2009

I'm glad i posted here. I would not have thought of using bracketed exposure.

In terms of the naming convention i'm not sure that is possible on my Camera (Canon 5dmk2).

I will have to look into it a bit more.

Daniel Sheehy · May 26, 2009

Bracketed RAW exposures should help.

If they're going for a stage wash so bright that the audience has to cover their eyes, I can see that looking quite good as a burnt out exposure...

Bob Hayes · May 27, 2009

I know it would be a pain to edit, but since you have such long intervals between photos, why not bracket the exposures? Have the camera take three in a row for each interval and then pick the frame with the best exposure? Of course, it creates a lot of editing work in post.

I believe there are some programs that control a digital camera and the f-stop. Some of the effects guys are using these to get precise multiple exposures on sets. Have the laptop control the f-stop.

Jake Iesu · May 27, 2009

Unfortunatly I am not able to run a laptop. The camera will be mounted to a lighting truss about 30 metres off the ground so logistically it is a pain in the ass to have a laptop up there however the budget does not cover the rental of a laptop either. One day I will get around to buying one.

I like the exposure bracketing idea. I will do a test shoot tomorrow and see how it goes.