Sony SAL1855 Service Manual page 35

3. Flange Back (f'F) Adjustment
Note:
Perform after completing the Focus-shift (Focal Length) adjustment.
1) Set the zoom to the WIDE end (18mm) and the focus to the over infinity end,
2) Focus by rotating the knob of flange back tester and read the flange back value.
3) Calculate the amount of increase or decrease of back adjustment washer by the formula below, using the result derived in step 2).
Amount of increase or decrease of back adjustment washer (mm) =
• In case that the amount of back adjustment washer is negative (-): Decrease the thickness of back adjustment washer.
• In case that the amount of back adjustment washer is positive (+): Increase the thickness of back adjustment washer.
4) According to the result calculated in step 3), increase or decrease the thickness of back adjustment washer.
• How to install the Back Adjustment Washer
1 Remove the switch panel block and the rear holding tube assy from the checking lens and make the checking lens as shown in
Fig. 4-4-2.
Three Screws
Back Adjustment Washer
2 Loosen the screws. Then, increase or decrease the thickness of back adjustment washer to meet the thickness of back adjustment
washer which is calculated in step 3), by pushing the back adjustment washers in between the boss and the mount. (3 locations)
Note:
Select 1 to 2 pieces of back adjustment washer to make a combination of specified thickness.
When stacking several pieces of back adjustment washer, install the washers so that the thin one comes at the outer side.
Be sure to use the back adjustment washers of same thickness at three locations.
5) Adjust by repeating steps 1) to 4) until the flange back satisfies the specification.
6) Measure the flange back values at each focal length and confirm that they satisfy the specifications in Table 4-4-1 and Table 4-4-2.
SAL1855 (DT 3.5-5.6/18-55 SAM) (DT 18-55mm F3.5-5.6 SAM)
Flange back f'F (measured value) of focal length "18mm" at over infinity end - 44.73mm
Back Adjustment
Washer
Back Adjustment Washer
Fig.4-4-2
Thin
Thick
Back Adjustment Washer
Part No.
3-870-687-01
3-870-687-11
3-870-687-21
3-870-687-31
3-870-687-41
3-870-687-51
4-1-2. Adjustment Flow Chart
4-8
Thickness t (mm)
0.05
0.1
0.25
0.3
0.35
0.4
Table 4-4-3