Sunday, March 17, 2013

Staying On Top: Nikon's Creative Lighting System

Getting Serious: In the world of Nikon speedlights, there are two schools of thought, manual or iTTL, each championed by one of two gurus. For the manual school, David Hobby carries the banner, while the iTTL advocates seek out Joe McNally for spiritual guidance. While they kid each other mercilessly, they do agree on one thing: a professional photographer must master both. You just have to be prepared when the "wheels fall off", and you're forced to resort to Plan B to get the project on track.

I admit to being a slow learner. I have relied heavily on iTTL along with the Nikon Creative Lighting System (CLS) when on assignment. Even with my lowly D70 cameras, the built-in flash can serve as a Commander for a speedlight (or more) set to receive signals on Channel 3 and Group A. This allows a single speedlight (I usually carry only one in the D70 bag) to be used remotely, off camera, if needed. Often this takes the form of my single SB-800 mounted on a monopod, with or without a light modifier of some sort. Come to think of it, there is also a SU-800 dedicated remote buried deep in the bag would I need more channels and more groups.

The assignment was to show two subjects discussing a floral arrangement. Because it was a pre-event shot, a finished product might have been illogical. But a shot of the two discussing the event, with a hint to their roles in that event, would probably do the trick.

The photo that appears at the top of this post is pretty straight forward in approach and technique. This sketch shot was taken at the highest possible flash sync speed to determine the background (street) exposure, which also gives me the widest corresponding aperture. When shooting indoors, I use aperture priority because I really don't know where the shutter speed will wind up. Outdoors, I resort to the Sunny Sixteen Rule. Once the exposure was determined, I would use flash to raise the inside level of illumination closer to that on the outside.

I have a great deal of confidence in the Nikon’s Speedlight System. When it works, it almost always produces well exposed images. Using simple adjustments from the controller speedlight mounted on the hot shoe, one can instantly adjust highlight and shadow detail by increasing or decreasing the power output of the different flash groups. And feedback is nearly instantaneous due to the previews that digital imaging provides. A nearly perfect system. Until it goes wrong.

The Setup: Initially, I set one speedlight, set to Group C, on the rear of the work table to throw some light onto the back wall to “loosen up” the underexposed areas in the rear of the photo. Next, a light stand mounted SB-800, set to Group A, was aimed where my subjects would be standing. The light was “modified” by shooting it through a Zumbrella. I purposely “choked up” on the umbrella shaft to insure that no light slipped past the Zumbrella’s edges and create a hot spot at the lower edge of the photo. I also pitch it up slightly to feather the light away from the flowers in the foreground. At first the umbrella was to camera left, and by design, the sensor eye on the flash was conveniently pointed directly at the camera mounted commander flash, which would also serve as fill.

Lighting Two Faces: The two subjects were posed, side by side, at a 90 degree orientation to each other. Kay, at camera right, was looking down into the open book she held, and Karen, standing at camera left, was looking Kay. This setup is not ideal because the lighting cannot compliment both faces at once. With my Zumbrella key light on my left, Karen’s face was partially in shadow, lit only by the fill. Kay, on the other hand, had the light perfectly aligned with her nose. Since the photo had to provide frontal exposure on both of their faces, I moved the light to my right side. This evened out the light distribution on the two faces, but introduced a double-handful of trouble.

My Oops Moment: First, by moving the light to my right, I had to re-arrange my speedlight so the body-mounted sensor eye faced the on-camera commander. The Nikon SB-800 does many things very well, but has some limits on rotation. The head can be rotated 180 degrees counterclockwise, but only 90 degrees clockwise. When I rotated the head and the body, I found that the sensor eye couldn’t quite rotate to a direct line of sight with the command. I started getting failures to fire because the sensor wasn’t seeing the controller. This wasn’t apparent until I started checking the images and saw that the key light was not firing consistently. I decided to back up slightly and continue shooting. This solved the flash problem, but because of the close quarters, completely changed the perspective.  These re-adjustments took time, something I was quickly running out of. Once I was back in control,  the composition, the expressions, and the lighting fell into place, and the photo made.

Remember For Next Time: Looking back, there were many things I could have done to get the project moving sooner and smoother. Here are some things I could have done.
  • Turn On The Sound Monitor: Remote Nikon Speedlights can be programmed to “beep” when they have returned to full power after flashing. Some years back, I turned all of my lights to “off” when the beep was being pick up by tape recorders during a musical performance.  Had I thought to turn this feature back on, the beep would have told me that the flash actually fired.
  • Test The Speedlights: There is a Flash Test Button on the back of the SB-800. When acting as a commander, the Test Button will fire the flash groups (A, B, and C) in sequence. If a flash fails to fire, you’ll know.
  • Flash Value Lock: This feature is available on the mid to upper tier Nikon bodies. It is a programmable function of the AE-L/AF-L Function (Auto Exposure Lock/Auto Focus Lock). By setting this function to FV-Lock (Flash Value), you take one flash reading by pressing the button on the back of the camera. The command remembers the correct flash output for each group which allows you to move about without change the speedlight output. Once this information is stored, the flash no longer needs to send a pre-flash. This seems to help with subjects who are “blinkers” because there is only one pre-flash instead of the multiple flash dialogue that accompanies every normal flash exposure under the CLS system.
Things went sideways when I lost line-of-sight contact between the on-camera commander and the remote flashes. Obviously, things returned to normal when contact was reestablished, but that breakdown took a long time to detect. These three steps will certainly help to let me know when things aren't working, since you won't tell what's going on until you stop and check the back of the camera. Remember too, that the introduction of your subjects onto the "set" may interfere with the communication between the controller and remote units, so be sure to test before, and during, the shoot. I plan on having a future post on Flash Value Lock. It appears to not be an option in the D40 clan of entry-level Nikon DSLR bodies. But the ability to lock in a flash value once and being able to change shooting positions and compositions has a lot of potential for overcoming some vexing flash exposure issues. More to come.