Karin Lau Photography

Possible Problems in Enlarging

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Intensity of enlarging light. Unless a stabilizer or other monitoring system is used, there is always the possibility of changes in the light intensity. Sometimes a change in electrical use within the building (such as turning on a heavy appliance) can lower the voltage, and thus the intensity of the enlarging light. Some enlargers are equipped with a meter that allows the voltage to be checked for variation, although it does not correct voltage. The "cold-light" illuminants See page 23 require a certain warm-up time to reach full output, < and thus they

should be left on, or "cycled" on and off regularly, throughout the see page 23 printing session. I now use the Horowitz cold-light stabilizer unit,^

which provides remarkably stable light output regardless of changes in voltage or tube temperature.

Vibration. The enlarger must be entirely steady during the exposure. Impact of the body against the worktable, or vibrations due to other causes (such as a darkroom exhaust fan) may reduce the definition, especially with enlargements of high magnification. Such vibrations can often be detected by viewing the grain through a high-power focusing magnifier; the grain should be steady and sharp in the viewer.

Reflections. Reflections of light leaking from the enlarger can cause fogging of the paper, and they sometimes are hard to locate. Reflections can be caused by bright metal enlarger supports, poor light seal at the lensboard, white walls reflecting light that leaks out around vents in the enlarger head or at the negative stage, bright objects nearby on the worktable, or even the beveled edges of the enlarging easel.

In some cases a source of reflection can be identified visually as you stand by the enlarger, but often the best means of detection is to examine the enlarger and its environment from the position of the paper, by looking into a mirror placed on the baseboard. Another method is to place a white focusing sheet in the easel and put a snug lens cap on the lens. Then turn off all lights and safelights in the darkroom and wait a few minutes for the eyes to adjust. Turn on the enlarger and try to see the paper in the easel. Light leaks in the enlarger should be quite apparent; often they can be repaired using black photographic tape, securely attached, but be certain not to obstruct ventilation holes in the enlarger head.