SAL2470Z2 - Sony Digital Camera Service Manual (repair manual). Page 22

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SAL2470Z2 (Vario-Sonnar 2.8/24-70 ZA SSM II) (Vario-Sonnar T* 24-70mm F2.8 ZA SSM II)

4-8

3)  Turn the mount rotation ring of lens test projector until the projected image at a certain peripheral point (y = 15 or 18) on the screen 

appears the most unsharp.

 

Read the number of the smallest pitched lines (both sagittal and meridional: 3 lines) at the peripheral point.
Note:

 

When reading the number of the smallest pitched lines, be careful of the spurious resolution.

 

 

Spurious resolution is the reversed image of 2 or 4 lines which appears on screen when focus is beyond maximum revolving power as shown 
in Fig.4-4-4.

 

 

Do not confuse spurious resolution for the smallest pitched lines.

 

Correct resolution

Spurious resolution

4)  Change the focal-length (zoom) and distance of the checking lens, and check that the all readings (y = 0, sagittal (S) and meridional 

(M) at y = 15 or 18) at each focal-length (zoom) and distance is within the specification of the Table 4-4-2.

Focal-length 

f (mm)

distance (m)

Center (y =0) 

(Lines per mm)

y = 15 (Lines per mm)

y = 18 (Lines per mm)

S

M

S

M

24

1.09

125 or greater

50 or greater

40 or greater

40 or greater

25 or greater

35

1.50

125 or greater

50 or greater

32 or greater

40 or greater

25 or greater

50

2.07

125 or greater

50 or greater

32 or greater

40 or greater

20 or greater

70

2.76

125 or greater

50 or greater

40 or greater

40 or greater

25 or greater

Check the projective resolving power. If it does not meet the specification, adjust the projective resolving power.

1.  Projective Resolving Power (Curvature of Field) Adjustment
 

When the position of maximum resolution locates peripheral, Adjust that position of center locates in front of 16 cm of peripheral.

 

Check the projective resolving power. Confirm whether the focused point should locate in front or at back of the focused center point, 
and adjust.

1)  Set the focal length of lens to 70 mm and adjust the focus so that the peripheral  y  = 18  reaches the maximum resolution.
2)  Confirm that where is the center when the maximum resolution is the peripheral. (Check whether it locates in front or back of the 

projected plane.)

 

A (mm): front(-), back(+)

3)  Set the focal length of lens to 24 mm and adjust the focus so that the peripheral  y  = 18  reaches the maximum resolution.
4)  Confirm that where is the center when the maximum resolution is the peripheral. (Check whether it locates in front or back of the 

projected plane.)

 

B (mm): front(-), back(+)

5)  According to the result in step 2) and step 4), calculate shift amount of the thickness of G4th-5th adjustment washer using the 

following formula.

Shift amount of the thickness of G4th-5th adjustment washer (mm) = ( B - A ) / 1600 + 0.07

 

In case of negative value (-) of shift amount: decrease the thickness of G4th-5th adjustment washer.

 

In case of negative value (+) of shift amount: increase the thickness of G4th-5th adjustment washer.

Example:  Focal length is 70 mm, if the position of center  y  = 0  locates in front of 100 mm of the position of maximum resolution of 

peripheral  y = 18 .

 

Focal length is 24 mm, if the position of center  y  = 0  locates in front of 50 mm of the position of maximum resolution of 
peripheral  y = 18 .

 

A = -100, B = -50

 

0.10125 (mm) = (-50 - (-100)) / 1600 + 0.07

 

Increase the G4th-5th adjustment washer of 0.1 mm.

6)  Adjust the shift amount according to the result in step 5).

 

If increase or decrease the G4th-5th adjustment washer, perform step 7) after doing  4-6-1. Flange Back (f F) Check .

 

 

When the checking lens is out of specification, perform  4-6-2. Flange Back (f F) Adjustment  and  4-5. FOCUS-SHIFT (FOCAL 
LENGTH) CHECK/ADJUSTMENT .

Part No.

t (mm)

3-298-864-01

0.05

3-298-864-11

0.07

3-298-864-21

0.1

 

G4th-5th Adjustment 
Washer

1st Lens Assy

Cam Ring Light
Shield Barrel

2nd Lens Assy

2nd Lens (Rear) Assy

2nd Lens (Front) Assy

7)  Set the focal length of lens to 70 mm and adjust the focus so that the peripheral  y  = 18  reaches the maximum resolution.
8)  Confirm that where is the center when the maximum resolution is the peripheral. (Check whether it locates in front or back of the pro-

jected plane.)

 

C (mm): front(-), back(+)

9)  According to the result in step 8), calculate shift amount of the thickness of 3rd-4th adjustment washer using the following formula.

Shift amount of the thickness of 3rd-4th adjustment washer (mm) = C / 1600 + 0.1

 

In case of negative value (-) of shift amount: decrease the thickness of 3rd-4th adjustment washer.

 

In case of positive value (+) of shift amount: increase the thickness of 3rd-4th adjustment washer.