A number of readers have asked that I repeat a tip from several years ago about how to perform a back focus, so here goes. If you have interchangeable zoom lenses for your video camera and they don’t hold focus when you zoom in or out, the back focus is probably out of adjustment. The easiest way to fix the problem is with a back focus chart. If you don’t have a chart, send me an e-mail at firstname.lastname@example.org, put “Back Focus” on the subject line and I will send you a free PDF file.
Once you’ve downloaded the file, print some hard copies, which I suggest carrying in your camera and lens cases.
To use it:
1. Place the chart about 12 feet from the camera.
2. Adjust the lighting or neutral density filters to allow shooting with the largest iris opening. This will result in the shallowest depth of field and most critical focus.
3. Zoom in as tight as possible on the chart and adjust the normal (or “front”) focus to make the fuzzy area in the center of the chart (called the circle of confusion) as small as possible. This will result in the sharpest image.
4. Zoom out to the widest image and adjust the lens’ back or flange focus ring to once again give the smallest fuzzy area.
5. Lock the ring.
6. Check the zoomed-in focus again to be sure it has not changed. You may have to work back and forth to reach a compromise where the front and back focus are each as sharp as possible.
The lens should now stay in focus when you zoom in and out.
“I’m doing more talking head corporate interviews, usually of men,” writes Anthony Burokas of Philadelphia. “What pieces should I get for a basic makeup kit?”
My kit is very small, just enough to handle a shiny head or fly-away hair. I believe that if more is needed, we should bring in a makeup artist so I can concentrate on my job as director of photography.
The “kit” is a tube of Lancôme T.Contrôle Matte Finish. This cream is an excellent “human dull spray.” It is translucent, so it works with any skin color, and it does very well toning down shiny skin or bald heads.
I also pack a few use-once-and-throw-away cotton makeup swabs and a small travel-size hair spray.
A word of caution: Always use disposable applicators. Never go back for a second helping of any makeup after the applicator has touched the subject. Throw it away and use a clean one. You could contaminate the makeup and pass something nasty on to your next subject.
More Enabled Entry
Here’s an alternative solution to the Christmas lights that we suggested for outlining backstage entries and the like sent in by Stan Teliczan of Riverside, Calif. Stan uses battery-operated electroluminescent (EL) wire, the cold light, low-current-draw lighting tool of choice for many Burning Man artists.
The EL wire comes in a variety of colors, and eight AA batteries will keep it glowing for a minimum of 24 hours. If it needs to cross a traffic area, the wire gets stuck down by a layer of clear packing tape.
The controller, battery box and excess wire can be stashed out of sight under a piece of duvetyn or a case lid, since the apparatus generates only a negligible amount of heat.
Stan says he has also used EL wire to outline edges of stages and orchestra pits, to create accents on set pieces and speaker lecterns, and even to outline the horn section of a jazz funk band playing at one of his gigs.
Most modern video cameras have tremendous depth of field. That’s great when you want it, but sometimes, like in an interview, you may want to concentrate attention on the subject by throwing the background out of focus. The easiest way would be to put as much distance as possible between the subject and the background. This is easy if you are shooting outdoors or in a very large venue.
A second tip is to back the camera away from the subject and use a longer lens or greater telephoto lens setting. (Longer lenses equal less depth of field.)
Third: If increasing the distance is not possible, try opening the aperture. (A larger lens opening also equals less depth of field.) But that can result in an overexposed image. I have a three-stop neutral density filter that helps a lot. You can also cut down the amount of light reaching the sensors by increasing the shutter speed.
Whatever you choose, experiment and practice before the shoot to find which combination you like the best. Then you can impress the client by recognizing the problem and knowing the solution immediately.