I
am not a control freak when it comes to most forms of photography. I
prefer to silently lurk in the background, observing the actions and
interactions of my subjects, and make a photograph when something occurs
that is emotional, sentimental, humorous, or visually interesting. This
candid moment was a grab shot, as you can see by my brother-in-law in
the background. This is the real me, "running and gunning", unfettered
by the need to have every photograph a contender for next year's
Pulitzer prize. I kid you.
One
might assume that this would be a typical available light photo,
since we're standing outside in bright sunlight. The problem comes from
the exposure extremes your camera's metering system must consider when
reconciling both highlights and shadows in the same photograph.
Normally, the camera would simultaneously meter them both and select a
compromise exposure, one that will inevitably overexpose the highlights
and underexpose the shadows.
In
this discussion, "highlights" are areas in the photograph that receive
their illumination from the sun, and "shadows" are the regions that
don't receive any direct sunlight.
For
this shot, I manually set the exposure as follows: 1/250 of a second
shutter speed (the shortest exposure that supports iTTL speed lights), F
16, and ISO 400. If you're old enough to remember the "Sunny 16 Rule", you would conclude that the image would be overexposed by 2/3 stop in a front-lit situation. Now
this would explain the brightness of the highlights, but what about the
shadows? I my case, I had a bare (no BFT or diffuser) SB-900, mounted
in the hot shoe and aimed straight ahead, but dialed down to 1/2 power.
(9/13/12: Ooops. I should have said it was dialed to -1/2 EV. This
means that the exposure from the speedlight would give 1/2 of the light
required for a full exposure. Sorry about that). Based on the Sunny 16 rule,
I am already overexposing the highlights by 2/3 stop. Now here's the
catch. My speed light, functioning as an on-axis fill light, is dropping
an additional 1/2 stop of exposure onto the shadows and on top of the
already "overly exposed" highlights. For you math over-achievers, the
highlights receive an over exposure of 2/3 of a stop, plus the addition
of 1/2 stop from the fill flash giving a total overexposure of slightly
more than one stop, 1 1/6 stop to be exact.
Now
examine the shadow areas in this portion of the lead photograph. The
shadows received 1/2 of the proper exposure from the speed light. If you
look at Suzi's face, you can see that the tip of her nose receives
light from the sun and the speed light, while the shadows are
illuminated by the fill flash. If you look under her chin, you can see
that without the flash, there would be very little shadow detail.
If
I had the presence of mind to refine my exposure, I would have reduced
the ISO to 125 which would have given me a "sunlight" aperture of F 11
and kept the speed light output at 1/2 power. I could then drop the
aperture to F 16 if the sunlit highlights were too bright. And I'm not
above reducing the speed light output even further, depending on what I
am trying to achieve.
In
an earlier post, I explained that you can use your speed light/s to
expose your subject any way that you want if you can place your subject
in a shadow of a building or tree. This shot combines a large key light
source and a small, on-camera flash for fill.
For
those who argue that "flash is dead" are missing an important point.
Sometimes you need some sunlight in your pocket to bring the details in
the shadows back to where they belong. In the end, it's all a matter of
altering the lighting conditions to better match what we thought we saw
at the time. And your built-in flash just won't have the power to be any
any use when wrestling with the sun.
