Darkening lighthouse?
I have been photographing lighthouses for the last five years. When I shoot a white lighthouse against a blue sky, the sky becomes an oversaturated shade of blue in my print. How do you think I can prevent this?
Robert Bishop
Hopewell, Va
When the white lighthouse dominates the frame, its brightness may mislead your exposure meter, “telling” the camera to reduce the exposure, thus darkening the sky. Even if your exposure is correct, the photo lab’s automatic printing machine could make the same wrong compensation. If so, ask the lab to reprint it at a slightly lighter setting. If the problem is your exposure, try metering off a neutral gray tone. Use a “gray card,” a gray sidewalk, or even the grass. Caucasians can meter off the palm of their hand and open up one-half to one stop. Watch out for saturated color films because they intensify the color. If you are using one, switch to a more neutral type.
Seeing orange
What is the purpose of an orange mask in color-negative film?
Harris Berkowitz
Santa Barbara, Ca
The mask improves the quality of color prints. But if you want the real story, here it comes, according to our resident film guru, Peter Krause. It involves the dyes that form the images on color film. Negative film has superimposed layers that contain silver-halide crystals sensitive to blue, green, or red light, respectively. They also contain colorless dye formers that can be converted into yellow, magenta, or cyan dyes when processed. In a perfect world, the yellow dye would absorb only blue light, the magenta dye only green light, and the cyan dye only red light. Yellow dyes meet this requirement, but magenta and cyan ones do not. Magenta dyes also absorb some red and appreciable amounts of blue light; cyan dyes absorb considerable green and some blue light. The net effect is a serious degradation of color. The elegant solution is to use colored dye couplers: a yellow-colored magenta coupler and a rose-colored cyan version. These “masking dyes” are split off from the dye formers during their transformation into the magenta and cyan image dyes by the color developer. The final color film image then consists of the desired negative components—yellow, magenta, cyan, and residual positive yellow and rose-colored masking dyes—that cancel the contrast of the additional absorbed colors, blue and green. Yellow and rose combine to make orange, and that is the long explanation of why the mask is orange. Now, aren’t you glad you asked?
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