In today’s lesson in my ongoing master flash course, a word or two about outdoor fill flash.

First: you need it, quite often, and for various reasons:

1. To fill in dark areas on those bright sunny days;
2. To brighten the foreground subject and get a darker background subject (i.e. to make your subjects “bright pixels”, which you have heard me say many times is a Good Thing, since Bright Pixels are Sharp Pixels);
3. To add a catch light in the subject’s eyes.

So what techniques are best to get pictures like this, at the wedding I shot the other day?

Trish at her wedding (Photo: Michael Willems)

When deciding on modes and techniques, look for where the issues may be; the constraints. The need to stay clear of these will help you decide the most appropriate modes and settings.

The issue in using on-camera flash outdoors is that (and follow the deductive reasoning here, step by step):

1. I want the darkground to be darker than the subject, as said above (especially when it is dark, like these plants).
2. Outside being well lit by our local star (that would be the sun), I can achieve that by means of a low ISO and small aperture.
3. But these will both reduce flash effectiveness! Exactly what I do not want on a bright day.
4. But fortunately I can also do it by selecting faster shutter speeds – these do not affect flash.
5. Until, that is, I get to the flash sync speed – beyond that, if I exceed that I can either no longer us flash at all, or I go to high-speed flash (Nikon: Auto FP flash), and that decreases the flash effectiveness enormously.

Ergo: my shutter speed should be at my flash sync speed (1/250th second on my 1Ds Mark III) before I start reducing ISO and increasing the f-number.

Ergo: I need to chose a mode where I set the shutter speed.

Ergo: Only Shutter Priority (Tv/S) or Manual mode will do. QED.

A common technique for finding a good fill-flash starting point when using an on-camera TTL flash in variable outside light:

• Tv/S exposure mode (Shutter priority).
• Select your camera’s flash synch speed (if unsure, select 1/200th second).
• Exposure compensation: -2 stops.
• Aim at your subject and check that aperture is somewhere around f/5.6. If not, change ISO until it is.
• Flash compensation: if and as needed (do a test shot. On a Nikon, and when shooting a bright white dress, you may need it, up (+). At other times, down (-) may be called for).

A common technique for finding a good fill-flash starting point when using an on-camera TTL flash in more predictable light (as on the day I shot the picture above):

• M exposure mode (manual mode).
• Select your camera’s flash synch speed (if unsure, select 1/200th second).
• Set Aperture (Av) until your meter reads -2 stops.
• Aim at your subject and check that aperture is now somewhere around f/5.6. If not, change ISO until it is.
• Flash compensation: if and as needed (do a test shot. On a Nikon, and when shooting a bright white dress, you may need it, up (+). At other times, down (-) may be called for)

The shot above was made in manual mode at 1/200th second at f/5.6, ISO 400.

Joseph Marranca and I will be teaching Advanced Flash as part of the “Advanced Creative Lighting” workshop we teach on August 13 in Millgrove, Ontario . Click here to learn more.