Sunday, June 27, 2010

Photography in the Last Days Before Oil?

In our continued series of seminars on photographic lighting techniques, Mark Sandoval and I took the class to the dunes of Panama City, Florida's St. Andrews State Park for an evening session of fun on the dunes working on balancing natural light and flash. We brought two willing sets of models, Zac and Michelle and Matt and Megan.

Deciding to shoot straight into the late afternoon sun - a great way to test your unorthodoxy while getting wonderful sunsets as backdrops - we hedged our bets in two ways: We began the easier way, by placing our models under a wooden walkway (shade is your friend) and bringing along the big Alian Bee 6400 (AB) and Vanguard II battery pack from Paul C. Bluff, in case the Nikon SB-900 needed some help nuking the late-but-not-quite-sunset. We had a lot of gear but decided to reflect the AB into a 42" white umbrella, for starters, with yours truly hand holding a 36" gold reflector for fill on the models in order to blend their lighting more closely with the warmer, late afternoon sun behind them.

In the grand style of David Hobby and Joe McNally, et al, we dropped the ambient 3 stops or so and then set the AB's power to correctly expose the models. An incident reading from 'Ole Faithful, my trusty Luna-Pro SBC analog light meter, gave me a starting exposure from the sun, quicker than trying-and-chimping the LCD on the camera - In bright sunlight, I find it especially difficult to get an accurate idea of exposure from either the LCD (too small) or, in some cases, the histogram (though that should always be consulted), more on that in a bit.

This type of WAS (Wild-Ass Shooting) is a "Blivit," which is defined, as you probably know, as putting 5 pounds of light into a 3-pound camera chip. The challenge is to balance 10 stops, plus, of exposure and cram it into 5 stops of (useable) camera chip latitude. The tools to do this that come with the camera are: "ASI" - Aperture, Shutter Speed, and ISO (what used to be called ASA, or "film" speed). That's it. And, since all three are more finite than anyone would like, it is sometimes a difficult balancing act. Of course, there are add-ons like neutral density filters, Polaroid filters, and firing off 40 or 50 magnesium flares, but those are a subject for another lesson.

Back to the Beach...

The setting from the incident reading, pointed straight into the sun, was F8 @ 1/50th of a second @ ISO 100. So, in order to bring this ambient exposure down 3 stops, we upped the shutter speed 2 stops to 1/200 sec. (we could not go 3 stops with the shutter because the camera would not sync. normally at 1/400th sec (there are other tricks but that, again, is another story...) . Therefore, since we were already at the lowest ISO available, we obtained the other stop with aperture, by changing to F11. Without resorting to cheating...ah, subterfuge... this is the only possible solution. Therefore, the F11 aperture sets the flash level, since it is independent of shutter speed (generally speaking, shutter speed is the variable that controls the ambient exposure and aperture is the variable that controls the flash exposure - whether you use the flash as fill or as main light).

Crank up the power, Igor! I shout to Mark, as the models look on nervously. Nailing the AB's power slider happens to put out F11 at our light-to-subject distance. If it didn't, we would have made use of the 'square of the distance rule' and moved the AB closer to the subjects, possibly terrifying them. Thank God, we didn't have to resort to such intimidating physics.

From there on, it was a matter of me holding the reflector while Mark blasted away, as our erstwhile models simulated '50's-era jitterbug dance moves in the lowering sunset. Apart from having to slow down - Mark gets excited easily and loves the double and triple-tap shutter technique - the fact is that an AB 6400 at full power, running on a battery pack cannot recharge like an SB900. Later, I will admonish him regarding his caffeine intake... Things went well enough, though it is easy to forget that the ambient is constantly changing, necessitating almost continuous adjustment of the shutter speed, if nothing else, especially since the flash remains a constant. One way to do this is to use aperature priority and set exposure compensation to -3. So long as you keep the flash-to-subject distance constant, you should get the desired effect and maintain the 3-stop ratio even as the sun goes down and changes the ambient light level. Of course, we did it the hard way, by manually changing the shutter speed to track the lowering light. Call it a learning experience...

In all, it was a great seminar in which we all learned a lot. One of the take-home lessons with this type of shooting - governed by nature as much as anything else, and changing so quickly that the whole, usable shooting window might be as short as 10 minutes - is the value of pre-visualization and planning of all elements of the shot ahead of time. Another is testing the equipment and set up before leaving for the shoot (we had difficulties with the Nikon changing its flash sync. values in mid-shoot from an errant touch of some button or other, in the may lay and excitement of the race with the sun, which limited our shutter speed to an unvariable 1/60th second - not funny). Figuring out what you want to do after you get to the shoot is not a workable idea - Copp's Law.

Talk soon with another exciting tale of Photo derring-do.

Stay well,

Bob Copp

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