Adjustment of F.F.D (ange-back focal distance)
When the suspected lens has been disassembled, be sure to make the following inspection and
adjustment.
For "∞ positioning" of the suspected lens, refer to "Software Manual of Lens adjustment for
Electrical Device".
Looking through the eyepiece of horizontal-type collimator, rotate the mirror micromotion-control
handle to adjust focus, then measure focus position at 28mm (WIDE-end), 105mm, and 300mm (TELE-
end). The focus position to be measured is the numeric number shown at the moment when the color of
cross lines changes from green to orange.
Focal length (f) Standard (mm)
28mm fm +0.05 to +0.13
105mm fm -0.03 to +0.35
300mm fm -0.20 to +0.50
If the measured values do not meet the standard, take the following step and make the readjustment.
Measure the values [A: WIDE-side (28mm) value, B: 105mm value, and C: TELE-side (300mm) value],
and input them into the software of lens adjustment for electrical device.
Based on the calculating results of the software of lens adjustment for electric device, adjust the
thickness of the below three washers [washer under 1st lens-G unit (#133: selected from A to I); washer
under 2nd lens-G unit (#80: selected from A to K); washer under mount (#79: selected from A to J)].
If the result is positive (plus), increase the thickness, while negative (minus), decrease it.
Washer under 1st lens-G unit (#133): Adjustment washer (ref. Page A43)
Washer under 2nd lens-G unit (#80): Adjustment washer (ref. Page A41)
Washer under mount (#79): Adjustment washer (ref. Page A36)
Caution: Put a thin washer between thick washers when assembled.
Use the washers in the limited range of the following:
Adjustment washer Limited range of thickness (mm)
Washer under 1st lens-G unit (#133: selected from A to I) fm 0.5 to 1.1
Washer under 2nd lens-G unit (#80: selected from A to K) fm 0.1 to 0.7
Washer under mount (#79: selected from A to J) fm 0.2 to 1.5
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