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OPM 4000
Coarse Adjustments
Filter Correction
5-4
Opacity Below Zero
If the opacity reading is below zero and you can not reach zero after you have
turned the adjustment knob as far as it will go into the zero jig housing,
perform the following procedure:
Do not force the knob. Stop at the first sign of binding.
1. Hold the zero jig in your hand so you can see the iris and retro reflector.
Turn the fine adjustment knob so that the iris is closed as far as it will go.
2. Loosen the coarse adjustment set screw.
3. Turn the fine adjustment knob in the opposite direction as far as it will
go.
4. Tighten the coarse adjustment set screw. Be sure not to tighten more
than 1/16 of a turn to prevent damage to the iris ring.
5. After the setscrew is tight again try to reach zero. Repeat if necessary.
Opacity Above Zero
If the opacity reading is above zero and you can not bring it up after you have
turned the adjustment knob as far as it will go into the zero jig housing,
perform the following procedure:
Do not force the knob. Stop at the first sign of binding.
1. Hold the zero jig in your hand so you can see the iris and retro reflector.
Turn the adjustment knob so that the iris is open as far as it will go.
2. Loosen the coarse adjustment set screw.
3. Turn the fine adjustment knob in the opposite direction as far as it will
go.
4. Tighten the coarse adjustment set screw. Be sure not to tighten more
than 1/16 of a turn to prevent damage to the iris ring.
5. After the setscrew is tight, again try to reach zero. Repeat if necessary.
6. After performing all of the above steps, if you can not reach zero, or zero
is unstable, contact the factory for assistance.
If you have an OPLR (correlation factor) other than 0.5, your neatral density
slides will read differently. To calculate what the slide will read with another
OPLR use the following formula:
Where:
OP1 = Standard filter value in %
M2 = OPLR for your instrument
M2
Op1
0.5
OP
1
1
*100 =
100
Instruction Manual
IM-105-4000, Rev 1.3
October 2008
2
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