Sunday, November 5, 2017

Spooky Lighting In A Large Room

Photo #1
Give Me An "A" For Effort: Halloween at the Adult School is a big thing during the day, and a not-so-big thing at night. This is because the nights are getting colder and there are there are fewer students participating (Many students are out with their own kids Trick or Treating).

My goal was simple: I wanted the convenience on on-camera flash but wanted my subjects to stand out from the background. And since Cissie was out Trick-Or-Treating, I was on my own.

Photo #2
I would be working in our large, multi-purpose room. As you can see, it's not particularly interesting, being lit by overhead fluorescent tubes of mixed color output. I decided to underexpose the image until only the tubes were lit, thinking they would make interesting visual highlights. You can see from Photo #2 that getting details in the ceiling meant letting the rest of the room go completely dark.

Since even lighting on the distant walls was not my goal, I decided to simply add some randomly placed speedlights to accent parts of the wall. Since I wanted the background to reflect a cold feeling, I decided to set the camera's white balance setting to Incandescent and let the ungelled background lights "chill out". This would mean that I needed to gel my key light source, an on-camera SB-800 speedlight with a full CTO taped in front of the flashtube. I added a Gary Fong Lightsphere to the speedlight and felt ready to start experimenting.

Composite #1
Five speedlights were placed on stands and aimed at the background walls. The arrows in Composite #1 shows where they were placed. There wasn't a practical way to light all four walls, so I had to try to shoot my subjects in front of the lit backgrounds. Incidentally, I set them to SU-4 Manual mode with flash outputs in the 1/8 to 1/16 power range.  Clearly there was more than enough power for the purpose.

Photo #3
Because my background lights were in SU-4 (optical slave) mode for its increased sensitivity, I couldn't use iTTL exposure on my shoe mounted SB-800. I shifted the speedlight to manual output, and after a bit of experimenting, determined that at 1/2 power, I'd need to stand 5 feet from my subject. I taped that reminder to the Cloud Dome and would endeavor to make all my shots 5' from my subjects. Photo #4 was a quick test to see that all the speedlights were working, and the exposure estimate was close enough for my purposes. It was taken at a distance of slightly more than my optimal 5' shooting distance, judging from the angle of coverage. Incidentally, I used a full frame DSLR, a D600, with a 15-30mm Sigma wide angle. The SB-800 was used with a supplementary Nikon SD-8a battery pack, so recycle time was reasonably fast.

Photo #5
Photo #5 followed the 5' rule and gave some pretty good results. So long as I kept my aperture constant, my backgrounds would always have the same exposure. The only trick was staying 5' from my subjects.

Photo #6
Medium Sized Groups: When doing small groups (Photo #6), I packed them as tightly as I could, and for these shots, went to full power to compensate for the increased flash-to-subject distance. Having a wide setting of 15mm allowed me to work at relatively short distances, but you can see a hit of light fall-off at the far left and far right of the frame.

Photo #7

Small Groups: This small group (Photo #7) took advantage of a bit of light coming from the side wall. While not an ideal photo, that hint of light in the background gave the subjects an improved sense of separation from the background. If you look at the background, you can see that the light from the on-camera flash doesn't light the background subjects very well. On the other hand, it helps to keep the viewers eyes "up front" and on your subjects.

Photo #8
Individuals: Even without the benefit of a back light, I still made some very acceptable photos with just the Cloud Dome (Photo #8). I did notice that my skin tones tended to be a bit on the warm side, a happy accident. I did not get a custom white balance for the CTO gel, instead relying on the camera's built-in Incandescent preset.

Photo #9 Exposure F8.0, 1/100 second, ISO 1600
The Final Takeaway: One thing I didn't initially catch was the extremely low output settings of the background speedlights. Meanwhile, my shoe-mounted main light was always shooting at near-maximum output, owing to the light-robbing CTO gel in front of the flash tube. Next time, I'll gel the background lights blue or green, remove the gel from the on-camera speedlight and set the white balance to Cloudy Bright, my usual default. I can probably find a happy medium between these two extremes, and still get a sense of "ghastly" coloration it the lighting.

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