Snowball in a Coal Mine
“Dynamic range” refers to the ability to hold detail in both the brightest and darkest areas of a scene. Although dynamic range has improved greatly with modern equipment, sometimes the folks who put on the events we cover forget that we can make video of a snowball in a snow field but not in a coal mine.
That was the case with one of my recent assignments. The producers of a worldwide, all-hands corporate meeting decided to use a large lectern painted gloss white to match their company logo (which I blocked in the photo to avoid embarrassing them). We had to stop down the camera lenses to keep from overexposing the video and the dark-skinned speaker almost became a silhouette.
Fortunately, we discovered the problem during rehearsal. I asked the lighting director to “flag off” (remove) almost all the light from the front of the lectern while leaving the rest of the stage as it was.
The event’s initial lighting setup violates one of the basic rules of lighting: “Your attention is immediately drawn to the brightest item in the picture.” That is why, when doing an interview, we try to have the background a stop or two darker than the subject.
The difficulty could have been completely avoided with some forethought by simply painting the lectern in a flat, light gray paint. It would still have photographed as white, but with much less of a dynamic range problem.
Need an emergency lighting dimmer? Stop by the hardware store and pick up a router or drill speed control. Mark Currier of Houston says it works. He also reminds us to check the white balance because you may get a color shift toward the red as the light dims.
White Balance Target
Speaking of white balance, a sheet of white flip chart paper makes an excellent camera white balance target. It is big enough, if set up horizontally, to put in the shooting area and still fill the frame from a distance, and small enough when folded to fit into your work box.
Rolling Mic Stopper
Hand microphones can roll and even fall to the floor when you leave them on a backstage table. Conrad Ziomek of San Jose, Calif., keeps his in place by putting them on a piece of the convoluted foam rubber normally used in cases to secure equipment. The foam provides a soft, non-damaging resting surface for the mics and the bumps keep them in place.
RTS Battery Danger
Several years ago I noticed what I consider a safety problem with the RTS wireless intercom battery packs.
There are two types of packs: one with rechargeable batteries and one with AA alkaline cells. Externally, they look almost exactly alike. They are easy to confuse in the dark, and both fit into the provided charger. Unfortunately, if you accidentally place an alkaline pack in the charger, there is a good chance it will overheat and possibly cause a fire.
At the 2005 NAB Show, I told RTS about a producer who told me he accidentally left the packs to charge overnight. When he returned in the morning, the charger was a blob of melted plastic. I have reminded them of the problem almost every year since and have suggested that they modify the alkaline case by putting a small “bump” on the side away from the transmitter. The bump prevents the packs from being inserted in the charger without interfering with their normal operation.
The problem was still there in a newly purchased system I worked with last week, so I am passing the message on to you.
It’s easy to make any packs in your kit safe by creating your own bump. Just glue the head of a plastic wire tie to the side of the case.