8.0 Rlf Compensation - CPI Indico 100 Series Service And Installation Manual

CPI Canada Inc.
3D.8.0 RLF COMPENSATION
The following points should be noted regarding RLF compensation. RLF compensation is normally only
needed if special techniques are used which result in AEC exposures greater than 100 ms.
•
If perfect, film would provide linear density changes with linearly increasing exposure times. In reality, at
longer exposures, film effectively becomes slower. This effect is known as reciprocity law failure. To
compensate, exposure times must be increased at longer exposures.
This compensation is achieved by increasing the AEC reference voltage at longer exposure times.
RLF compensation is applied to three ranges (50-500 ms, 500-1000 ms, and 1000- 1500 ms) as shown
below.
The examples below are not meant to represent actual RLF compensation percentages in your
installation. Actual values will need to be determined per the procedure following.
•
Between 0 and 50 ms no RLF compensation is applied. Per figure 3D-14, the AEC reference voltage is
constant at 1 unit between 0 and 50 ms.
•
At 50 ms, RLF compensation = 10% is applied. This means that the reference voltage will increase by
10% between 50 ms and 500 ms in a linear fashion. At 500 ms the reference voltage is then 1.0 X 1.10 =
1.10 units.
•
At 500 ms, RLF compensation = 20% is applied. This means that the reference voltage will increase by
20% between 500 ms and 1000 ms in a linear fashion. At 1000 ms the reference voltage is then 1.10 X
1.20 = 1.32 units.
•
At 1000 ms, RLF compensation = 30% is applied. This means that the reference voltage will increase by
30% between 1000 ms and 1500 ms in a linear fashion. At 1500 ms the reference voltage is then 1.32 X
1.30 = 1.72 units
•
The rate of increase of the reference voltage beyond 1500 ms will be constant, up to limit of the B.U.T.
(backup timer).
•
The compensation curve resulting from the RLF values described above is depicted in the graph below.
Millenia / Indico 100 Series Service Manual
Figure 3D-14: Example RLF compensation curve
Ch # 740904-06
AEC Calibration
Rev. D
3D
Page 3D-35