Sony SAL2470Z Service Manual ▷ View online
4-24
SAL2470Z (Vario-Sonnar 2.8/24-70 ZA) (Vario-Sonnar T
*
24-70mm F2.8 ZA SSM)
2. Checking Method
1)
Turn the focus ring of the checking lens until the chart image projected on the screen is the sharpest at the center (y’=0).
2)
Read the number of the smallest pitched lines at the center (y’= 0).
Fig.4-4-3
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 saggital 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.
Fig.4-4-4
4)
Change the focal-length (zoom) and distance of the checking lens, and check that the all readings (y’= 0, saggital (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.
Specification
Focal-length distance (m)
Center (y’=0)
y’= 15 (Lines per mm)
y’= 18 (Lines per mm)
f (mm)
(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
Table 4-4-2
The number represents for lines per mm.
Saggital (S)
Meridional (M)
Correct resolution
Spurious resolution
4-25
SAL2470Z (Vario-Sonnar 2.8/24-70 ZA) (Vario-Sonnar T
*
24-70mm F2.8 ZA SSM)
4-4-2. Projective Resolving Power Adjustment
Note:
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 maximaum 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 maximaum 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 periph-
eral “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).
Note:
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. Focus-shift/Flange Back (f’F) Adjustment” and “4-5.
FOCUS-SHIFT (FOCAL LENGTH) CHECK/ADJUSTMENT”.
G4TH-5TH ADJUSTMENT WASHER
Part No.
t (mm)
3-298-864-01
0.05
3-298-864-11
0.07
3-298-864-21
0.1
Table 4-4-3
Ver. 1.4 2012.08
The changed portions from
Ver. 1.3 are shown in blue.
Ver. 1.3 are shown in blue.
4-26
SAL2470Z (Vario-Sonnar 2.8/24-70 ZA) (Vario-Sonnar T
*
24-70mm F2.8 ZA SSM)
Fig.4-4-5
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 maximaum resolution is the peripheral. (Check whether it locates in front or back of the
projected 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
(1) In case of negative value (-) of shift amount: decrease the thickness of 3rd-4th adjustment washer.
(2) In case of positive value (+) of shift amount: increase the thickness of 3rd-4th adjustment washer.
Example
If the position of center “y’ = 0” locates in front of 50 mm of the position of maximum resolution of peripheral “y’ = 18”.
0.06875 (mm) = -50 / 1600 + 0.1
Increase the 3rd-4th adjustment washer of 0.07 mm.
3RD-4TH ADJUSTMENT WASHER
Part No.
t (mm)
2-899-276-01
0.05
2-899-276-11
0.07
2-899-276-21
0.10
2-899-276-31
0.20
Table 4-4-4
G4th-5th Adjustment
Washer
Washer
1st Lens Assy
Cam Ring Light
Shiled Barrel
Shiled Barrel
2nd Lens Assy
2nd Lens (Rear) Assy
2nd Lens (Front) Assy
4-27
SAL2470Z (Vario-Sonnar 2.8/24-70 ZA) (Vario-Sonnar T
*
24-70mm F2.8 ZA SSM)
Fig.4-4-6
10) Mark the mount index side of the 4th lens holder using a permanent marker, remove the 4th lens assy.
11) Increase or decrease the 3rd-4th adjustment washer according to the result in step 9), align the marking part of 4th lens assy to mount
index side and install it.
12) If the projective resolving power does not meet the specification, adjust again.
Note:
If increase or decrease the 3rd-4th adjustment washer, perform “4-6-1. Flange Back (f’F) Check”.
When the checking lens is out of specification, perform “4-6-2. Focus-shift/Flange Back (f’F) Adjustment” and “4-5.
FOCUS-SHIFT (FOCAL LENGTH) CHECK/ADJUSTMENT”.
2. Projective Resolving Power (Partial Blur) Adjustment
Check the projective resolving power. Conform the following adjustment if necessary.
1)
Set the focal length of lens to 70 mm and adjust the focus so that the center “y’= 0” reaches the maximum resolution.
2)
Check projective resolving power at reach peripheral point of “y’= 18”.
(1) If the projective resolving power does not meet the specification, rotate the 4th lens assy, adjust the defective parts to out of
picture frame.
(2) If the adjustment is impossible according to the procedure (1), replace the 2nd lens assy.
Rear Light Shiled Barrel
3rd-4th Adjustment Washer
4th Lens Assy
4th Hold Washer
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