Source Four - Lamp Adjustment

Lamp Adjustment

Lamp adjustment, or bench focus, is used to achieve an even field of light, and to remove hot-spots which can destroy color filters. On the Source Four, adjustment can be done without tools, and is more accurate than previous instruments, compared to the four-screw assembly. With this assembly it is often difficult for lamps to maintain alignment. The most common problem is the lamp dropping too low in the reflector, causing a hot spot at the bottom of the beam, and a dark area at the top. This may be corrected by a realignment of the lamp.

There are two adjustments that can be made to the cap.

1. The center screw controls the depth of the lamp into the reflector. Loosening this screw causes a spring to push the lamp further inside the reflector, creating a brighter hot spot in the beam. Tightening this screw will draw the lamp backwards, for a flatter field.

2. The wider wing nut that sits underneath the center screw controls the placement of the lamp within the reflector. Loosening this wing nut will free the lamp assembly from the cap housing. The user can then push the entire adjustment screw and lamp holder up, down, left or right to center the hot spot in the beam. It is this adjustment that most commonly needs to be made with lights that haven't been regularly serviced. Sometimes it is helpful to use a screwdriver or wrench or other thin tool to reach between the body of the light and the cap to push up on the lamp holder assembly and hold it in place while you tighten the wing nut back down.