Sony SAL55200-2 Service Manual page 25

4-5. FOCUS-SHIFT (FOCAL LENGTH) /FLANGE BACK (f'F) CHECK/ADJUSTMENT
In this section, the check/adjustment of focus-shift, which arises from the change of the focal length by zooming, is described.
Equipment
• 1000 mm Collimator
• Flange Back Tester
• A-mount Attachment
• Flange Back Gauge (43.50mm)
4-5-1. Focus-shift (Focal Length) /Flange Back (f'F) Check
1. Preparations
1) Perform "LENS GENERAL ADJUSTMENT GUIDE 3. FLANGE BACK (f'F) CHECK/OPTICAL AXIS CHECK"
2. Focus-shift (Focal Length) Check
1) Set the zoom to the TELE end.
2) Set to "44.56mm" by rotating the knob of flange back tester.
3) Focus by rotating the focus ring from the near end side.
4) Rotate the zoom TELE → WIDE and WIDE → TELE and confirm that the value at each focal length satisfies the specification.
Note:
Do not rotate the focus ring
Specification
Focal Length f (mm)
200
135
100
70
55
5) If the flange back value (f'F) of the checking lens does not satisfy the specification in Table 4-5-1, perform "4-5-2. Focus-shift (Focal
Length)/Flange Back (f'F) Adjustment".
3. Flange Back (f'F) Check
1) Set the zoom to the TELE end and the focus to the over infinity end and then check that the flange back satisfies the specification.
Specification: Over infinity end
Focal Length f (mm)
200
2) If the flange back value (f'F) of the checking lens does not satisfy the specification in Table 4-5-2, perform "4-5-2. Focus-shift (Focal
Length)/Flange Back (f'F) adjustment".
SAL55200-2 (DT 4-5.6/55-200 SAM) (DT 55-200mm F4-5.6 SAM)
Flange Back Value f'F (mm)
44.56 ( ±0.15) (44.41 to 44.71)
44.56 ( ±0.14) (44.42 to 44.70)
44.56 ( +0.14, -0.05) (44.51 to 44.70)
Table 4-5-1
Flange Back Value f'F (mm)
46.12 ( ±0.2) (45.92 to 46.32)
Table 4-5-2
4-1-2. Adjustment Flow Chart
4-11