Monday, November 8, 2010

Flash vs Ambient

Yesterday I was lucky enough to help out Brent Pearson with his Off Camera Flash on Location workshop.

Where Brent leant towards a lightmeter, I ran the students through working out an exposure without one.

Here's a quick re-cap:

Use your Camera as a Lightmeter
Sunny 16
I set the camera to AV (Aperture Priority) mode, and picked an appropriate working aperture. We were in full sunlight, so I knew I'd have to start small, F/8, ISO100.

Camera said 1/200th. It's a subtle point, but, the camera has just metered the light. We're about a stop off a Sunny 16 exposure.

An alternative is to set the camera to TV mode, and start with, say, 1/100th, the camera would then meter, and give an aperture - in this case, it would have been F/11.

Underexpose to Taste
Generally, I like contrasty photos, so I like to underexpose backgrounds by two stops where I can. Sometimes I'll go to 1 stop or less for a more 'natural', and less 'lit' kind of picture.

It's down to taste.

From F/8, ISO100, 1/200th, two stops gets us to F/16, ISO100, 1/200th. There are a lot of great resources around explaining this for anyone who is puzzling over it.

The brightness of the picture has dropped off a lot, but I can see what I'll get for any part of the picture not touched by flash. Importantly (for me) the saturation in some of the colours comes up.

Add Flash
Add Flash
I had the luxury of a flash that could belt out enough power here. That's one of the top reasons anyone would invest in a bigger flash unit like the AB1600.

Essentially now, the majority of the light is coming from the flash, and the sun is largely 'filling' the shadows.

But, because of the very directional light from the sun, there's some strange shadows where the key (flash) light is in a different direction to the sun.



Don't rest on your laurels, now the light is sorted, get a good shot!
(FWIW, this was the third shot I took after the light was set)


  1. Thanks for this. How did you fix the issue of the strange shadows caused my the cross-lighting though?


  2. Hmm... small world.

    About to start the whole strobist thing myself. Looks like I have a lot to learn.

    Nice post.

  3. Sorry I'm a bit slow replying...

    @IanW: By chance, I didn't really get it in any of my pics before we changed the lighting setup.

    Unfortunately, a bunch of the students did :(

    I'd say, adjusting the pose or moving the lights are the best solutions.

    @Simon: it's a lot easier to practice on food - it'll stay still for a lot longer without complaining too much ;)