Balancing flash and ambient light

2010-09-24

in Daily updates, Geek stuff, Photography

I am taking a photojournalism and documentary photography class through the School of Photographic Arts: Ottawa. The first assignment is balancing flash with ambient light, taking photos of strangers outside at night. It is strongly encouraged to take photos in manual mode, rather than the aperture priority mode I normally use. As such, I am learning to adjust my thought process.

Normally, my thinking when it comes to exposure settings looks something like this:

  1. Will the lighting be changing quickly, not leaving me enough time to change settings? If so, choose a suitable ISO and white balance, set the camera to ‘program’ mode and hope for the best.
  2. If not, choose a combination of ISO and aperture that is suited to the light and the amount of depth of field I want.
  3. Make sure the shutter speeds generated are suitable to the situation, subject, and lens.
  4. Adjust ISO and white balance as necessary.

Switching to manual and balanced flash/ambient light requires choosing an appropriate aperture, then selecting a suitable shutter speed that will underexpose the subject before the addition of E-TTL II metered flash. It’s a workflow that takes some getting used to, but which ought to be helpful in the long run.

Particularly during the dancing at the end, my photos from my cousin Ksenia’s wedding could have used a bit of flash to top up the ambient light.

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{ 8 comments… read them below or add one }

Tristan September 25, 2010 at 1:41 am

What’s wrong with using P mode, auto ISO and slow or rear curtain sync?

Oh wait – I forgot; photo professors love to make easy tasks seem absurdly complex.

Tristan September 25, 2010 at 1:43 am

“Make sure the shutter speeds generated are suitable to the situation, subject, and lens.”

This makes no sense. If you are going to use a short shutter speed, you’ll have to crank the ISO to get the fill you want – which means your flash-lit picture will be near as grainy as the ambient light picture you could have taken.

Try P, auto ISO, -1 exposure (not flash exposure) compensation.

Tristan September 25, 2010 at 2:18 am

“Adjust ISO and white balance as necessary.”

If you are using flash, your white balance should be set to “flash” temperature. I can’t remember whether that’s 5 or 6k.

Although – if you want to be really fancy, you could carry a set of warming or cooling gels to match flash temperature to the ambient light.

Milan September 25, 2010 at 11:18 am

You don’t necessarily want to use flash white balance. For instance, you could be using mostly ambient with just a tiny bit of flash power. Alternatively, you might want the flash-lit portions to look blue.

Tristan September 25, 2010 at 12:26 pm

That’s true. Still – if you’re getting serious about flash fill with ambient light it might make sense to start carrying around flash gels.

alena September 27, 2010 at 12:33 am

I loved the photos from Ksenia’s wedding. You did a great job. Enjoy the course and I hope that you will learn some new skills.

magictofu September 27, 2010 at 12:16 pm

Flash is a very short burst of light. Therefore you can adjust background/ambiant exposure without changing exposure of your lit subject (whose exposure depends mostly on aperture) by changing your shutter speed (within sync speed of course) or vice versa. This can be done quickly in manual mode or by using needlessly complicated exposure and flash compensation.

Of course what people mean by balancing ambiant with flash encompass so much more, including light ratios and white balance.

Milan October 25, 2010 at 11:33 am

I am getting used to manual mode, and it is more useful than I thought. It certainly produces ‘artier’ looking photos than the more automatic modes, though there are also more that do not turn out properly.

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