Sony SAL1855 Service Manual ▷ View online
4-6
SAL1855 (DT 3.5-5.6/18-55 SAM) (DT 18-55mm F3.5-5.6 SAM)
4-4.
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)
4-4-1. Focus-shift(Focal Length)/ / Flange Back (f'F) Check
1. Preparations
1)
Perform “LENS GENERAL ADJUSTMENT GUIDE 3. FLANGE BACK (f'F)/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)
By rotating the zoom TELE
t WIDE and WIDE t TELE, confirm that the flange back value at each focal length satisfies the
specification.
Note:
Do not rotate the focus ring.
Specification
Focal Length f (mm)
Flange Back Value f'F (mm)
18 to 55
44.56
±
0.12 (44.44 to 44.68)
Table 4-4-1
5)
If the flange back value (f'F) of the checking lens does not satisfy the specification in Table 4-4-1, perform “4-4-2. 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.
2)
Set the zoom to the WIDE 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)
Flange Back Value f'F (mm)
18 (WIDE end)
44.73
±
0.05 (44.68 to 44.78)
55 (TELE end)
45.98
±
0.54 (45.44 to 46.52)
Table 4-4-2
3)
If the flange back value (f'F) of the checking lens does not satisfy the specification in Table 4-4-2, perform “4-4-2. Focus-shift (Focal
Length)/Flange Back (f'F) adjustment”.
4-1-2. Adjustment Flow Chart
4-7
SAL1855 (DT 3.5-5.6/18-55 SAM) (DT 18-55mm F3.5-5.6 SAM)
4-4-2. Focus-shift (Focal Length)/ Flange Back (f'F) Adjustment
1. Preparations
1)
Perform “4-4-1. Focus-shift (Focal Length)/ Flange Back (f'F) Check” and confirm that the flange back(f'F) at each focal length does
not satisfy the specification in Table 4-4-1.
2)
Remove the focus ring.
3)
Remove the front decoration plate and front ring.
2. Focus-shift(Focal Length) Adjustment
1)
Set the zoom to the WIDE end and the focus to the over infinity end.
2)
Focus by rotating the knob of flange back tester. At this moment, read the flange back value.
3)
Add “1.25” to the read flange back value. Then, rotate the knob of flange back tester so that this added value can be achieved.
Example) In case that the read value is 44.80: 44.80 + 1.25 = 46.05 (mm)
4)
Set the zoom to the TELE end.
5)
Loosen the screw fixing the 1st lens barrel block and adjust the focus by moving the fixing screw in the arrow direction.
6)
Tighten the screw fixing the 1st lens barrel block.
7)
Adjust by repeating steps 1) to 6) so that the focus at the WIDE end becomes the same as that at the TELE end.
Fig.4-4-1
Screw
4-8
SAL1855 (DT 3.5-5.6/18-55 SAM) (DT 18-55mm F3.5-5.6 SAM)
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) =
Flange back f'F (measured value) of focal length “18mm” at over infinity end - 44.73mm
• 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.
Fig.4-4-2
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.
4-1-2. Adjustment Flow Chart
Back Adjustment Washer
Part No.
Thickness t (mm)
3-870-687-01
0.05
3-870-687-11
0.1
3-870-687-21
0.25
3-870-687-31
0.3
3-870-687-41
0.35
3-870-687-51
0.4
Table 4-4-3
Back Adjustment
Washer
Washer
Three Screws
Back Adjustment Washer
Back Adjustment Washer
Thin
Thick
4-9
SAL1855 (DT 3.5-5.6/18-55 SAM) (DT 18-55mm F3.5-5.6 SAM)
4-5.
FOCUS-SHIFT CHECK/ADJUSTMENT (APERTURE (AMOUNT OF SPHERICAL
ABERRATION))
ABERRATION))
In this section, the check/adjustment of focus-shift, which arises from the change of aperture, is described.
Equipment (Only the specific equipment is listed.)
• Aberration Measuring Cap 55mm (SAL1855)
4-5-1. Focus-shift (Aperture (Amount of spherical aberration)) Check
1. Preparations
1)
Perform “LENS GENERAL ADJUSTMENT GUIDE 5. FOCUS-SHIFT CHECK (APERTURE (AMOUNT OF SPHERICAL
ABERRATION))”.
2. Confirmation
1)
Set the zoom to the TELE end (55mm) and the focus to infinity and over.
2)
Check the focus-shift (amount of spherieal aberration) and confirm that the focus-shift satisfies the specification below.
Specification: -0.10 to +0.14
3)
According to the result in procedure 2), perform “4-6-5.
SB Check/ Write
SB”, using the lens adjustment program.
4-1-2. Adjustment Flow Chart
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