How to light and use flash in large rooms with dark ceiling and colored walls?

Question

While reading "Using on camera flash in banquet hall with high ceilings", I realized that I have a similar problem at hand.

I regularly (at least twice a year) shoot conferences for a large company.

These are held in a wide but narrow room (I would guess 15 * 45 * 3m (L*W*H) with one wooden wall (think of walnut), and three yellow-colored leathery walls, a dark floor (think of dark oak) and a black, moderately reflective ceiling. One side features 1m high, shaded windows, the ceiling's lights are small HQI-lamps, while the speaker's desks are lit by tungsten PAR64 (50% output at best).

^{Photo of the location (from front to back). 24mm, 1/125s | f/5.6 | ISO 6400, E-TTL flash fired (angled via ceiling). I am standing next to the wooden wall and 5m in front of the stage. Notice the dark-semi-reflective ceiling and the yellow walls.}

Without flash, ISO 6400 @ 1/100s and f/5.6 is underexposed by around 1-2 EV (depends on the exact location). 1/80 or faster are needed, as I need to stop peoples' motions, and f/4 or narrower is needed (often), as most pictures feature groups of people and/or a background that should be discernible.

^{I know that this is a very specific description of the situation - I thought that it would be better to offer specific conditions and get general answers than having it vice versa.}

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My solution is to angle the hotshoe-flash (GN 52) slightly towards the subject (so not straight upwards) and using a large bounce card (out of paper for now, but I plan to design one myself with oblique white arylic glass). For group pictures, I use multiple flashes off-camera with a similar setup. For pictures of the PAR64-lit area, I use a CTO gel.

Generally, I use manual mode, but leave the flash at E-TTL and only play around with the flash exposure compensation.

The flash offers fairly little compensation - it needs very high power levels to offer any support and because of the reflectiveness of the ceiling, it does not offer a soft light. This means that while the flash offers a bit more light, it does little for eye-shadows.

My solution works - my employer is happy with the photos (at least that is what they say), but to me, the pictures are too noisy and too flat.

Aside from asking the room's technician to give me as much ambient light as possible (and perhaps using CTB-gels for the PAR64s), are there other improvements to my setup or other solutions for this kind of situation that I have missed so far?

Answer 1

No. Do not try to illuminate the room using a flash.

The way you are taking photos is not bad at all, it probably needs some white balance. The only thing you can do is either get a better performing camera in dark situations or to reduce the noise using software like "Neat image".

Another two programs I think make a good job removing noise are Dxo and Topaz labs.

Here is a before and after removing noise. I used the whiteboard as the noise sample, but you can profile the specific noise of your camera at your specific ISO.

This kind of scenarios must use the ambient light.

Shoot on Manual Mode and decide what is the minimum speed you are willing to take. You can easily go for 1/60 or 1/50 as you are shooting on a wide angle lens, even without a tripod. And it is not like people are running after a ball. You can have a bit less noise there.

For the white balance, it is difficult to tell, but as always... shot in Raw.

Take a measure of a white piece of paper under direct light of the main lamps, where people are sitting, and use it as a reference. Of course, you can use a Macbeth color card if you have some more time, or as you use that room often.

You also can develop a "flavor" and apply it to all the photos of that room.

Try to brighten up the scene a bit, probably lifting the gamma to around 1.2 or lifting the shadows only and remove a bit of green using curves.

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Using a flash will put you in more trouble than it solves.

You will have a different white balance that you need to correct on location, using gels on your flash.

And also you will have an overexposed zone that will decay rapidly. Making the flash too obvious. This a "worst-case scenario" for the inverse square law.

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The only moment you need flashes on that situation is to take a direct portrait of someone on that room and keep the flash as dim as possible, depending on the real intensity of the light on the room. Try to use it as a fill light to reduce any unwanted direct light of one spot on the ceiling.

Some diffusion on that flash would be nice.*

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* Regarding the diffuser, you are using... I would not relly on acrylic. Synthetic white materials tend to have some color tint, normally magenta-ish or purple-ish color. You need to measure it, but I rather prefer paper or white painted material.

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On some different room, with higher ceilings (really higher, like a church) and a neutral tint on it, firing a flash to it might give you one more step of light, either to reduce the ISO or the shutter speed. I would use it for the shutter speed.

Answer 2

1. You might consider firing multiple flashes together into a single light modifier. Something like a quad bracket would allow you to do it with a single light stand. Every time you double the number of flashes, you increase the maximum total light by one stop. (e.g. add one extra stop with two flashes, add two extra stops with four flashes...)

2. A wireless trigger system for this type of location would be essential if you don't already have one.

3. If you have two light stands all set up with flashes and light modifiers mounted, you can carry one in each hand and set them down wherever you want to shoot your next image.

4. The room might be a bit large for this to be practical, but you could also add a few additional flashes in to illuminate whatever will be in the background of your images. If you have enough flashes to illuminate the scene to your liking, you can simply set your shutter speed to the max sync speed and effectively "turn off" all the ambient light. If these background lights will be in the same place for a while, you might consider setting them to manual mode for consistent exposure.