Technical Support Document 038 - 10/96

NOTES ON APPLICATION OF NEUTRAL-DENSITY FILTER TO STARLITE 55 COLOR SENSOR

In the event that the Starlite 55 light output is able to "over-power" the head's internal color sensor, a Neutral Density (ND) filter can be attached to the color sensor's window to limit the light level entering the sensor's "eyes." After the head is re-calibrated with the ND filter in place, it will operate properly.

A Starlite with this condition will exhibit a limited density output range, with the light going to a deep filtration of one color, usually red, at higher light levels.

Recommended amount of ND filtration over sensor: 80CC (2-2/3 f-stop)
Recommended area of application: Over Sensor Window (Not on the Mixing Chamber window.)

High-quality ND filter material should be used. However, avoid "gelatin" filter material, since it would not hold up well in the open where it is installed. After the new filtration is in place, re-install the color sensor and power-up the Starlite. After the main screen comes up, go into the STARLITE DIAGNOSTICS menu and select item #7: AUTO-CALIBRATE SENSOR. After the head finished the calibrate routine, check that the main screen filtration values are as follows:

Note: You will have to make the LAMP POWER DISPLAY item ACTIVE in the Starlite Preferences menu to view the lamp power. This value will be displayed when the lamps are turned ON.

If the time or lamp power values are not correct, you may want to repeat the AUTO CALIBRATE routine. The second application will set things to the correct values. This is a normal characteristic of the Starlite's AUTO CALIBRATE routine.

Testing for Color Sensor's Light Reading Range:

To check that the color sensor is not being over-powered by the light in the mixing chamber, follow these steps. (Note that this can be done gefore ND installation to see if there's a problem.) The problem in question here is whether the sensor voltages are "pegged" or "maxed-out" when the lamps are running at or near their maximum output power.

Set the MAXIMUM LAMPS POWER to 99%, as high as it will go.
Go into the MANUAL CONTROL TEST in the STARLITE DIAGNOSTICS menu.
Move all the filters out of the light path by pressing and holding, in turn, the <3>, <6>, and <9> keys. Also move the shutter all the way open by using the Down Arrow key under the <9> key.
Turn the lamps ON by pressing the LAMP key. The lamp will come on at full power.
Examine the three numbers in the lower, left area of the screen. These numbers should all be just under 3500 in value (3000-3499). The CYAN number usually the highest in value.

Carefully note the values of the three numbers. These are the voltages from the color sensor.
Click the lamp power down one step by pressing (but not holding) the Down Arrow under the CANCEL key. The RMS Voltage should decrease slightly.
Most importantly, all three of the sensor voltage numbers should decrease. You can use the right-hand set of arrow keys to move the lamp voltage between it's maximum value and the next lowest step to verify that the sensor voltages are responding at both lamp voltage levels. The sensor voltage readouts will change about 20-30 points with each step of lamp voltage.
If the voltages stay the same whilst the lamp RMS voltage changes, then the sensor is overloaded. You will need to install ND over the sensor window. If you already have installed ND over the sensor, try an additional layer.

If the sensor voltage numbers respond at any level of light, the sensor is operating within an acceptable range, and no additional ND filtration will be necessary.

If you have any questions about this procedure please contact ZBE at the addresses and numbers below.