Sony SAL70200G (serv.man2) Service Manual ▷ View online
5-20
SAL70200G (2.8/70-200 G) (70-200mm F2.8 G)
2)
Attach the checking lens to the lens test projector, and set the equipments as shown in Fig.5-3-2.
3)
Turn the fan switch of the lens test projector to ON, then turn the lamp switch to ON.
Fig.5-3-2
4)
Turn the focus ring of the checking lens until the chart image projected on the screen is the sharpest at the center (y’=0).
5)
Set the plane mirror to the center of the projected image (y’= 0), and adjust the projector position so that the mirror reflects the light
to the center of the lens.
Distance
Lens test projector
Chart
Fan switch
Lamp switch
Plane mirror
Screen
A-mount attachment
Checking lens
F
L
5-21
SAL70200G (2.8/70-200 G) (70-200mm F2.8 G)
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.5-3-3
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. 5-3-4.
Do not confuse spurious resolution for the smallest pitched lines.
Fig.5-3-4
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 5-3-2.
Specification
Focal-length distance (m)
Number of the smallest pitched lines
f (mm)
Center (y’=0)
y’= 15 (Lines per mm)
y’= 18 (Lines per mm)
(Lines per mm)
S
M
S
M
70
3.16
125 or greater
63 or greater
50 or greater
50 or greater
40 or greater
135
5.7
125 or greater
63 or greater
32 or greater
50 or greater
32 or greater
200
8.09
125 or greater
63 or greater
40 or greater
50 or greater
40 or greater
Table 5-3-2
The number represents for lines per mm.
Saggital (S)
Meridional (M)
Correct resolution
Spurious resolution
5-22
SAL70200G (2.8/70-200 G) (70-200mm F2.8 G)
5-3-2. Projective Resolving Power Adjustment
Check the projective resolving power. If it does not meet the specification, adjust the projective resolving power.
1.
Rotate the 1 group ball frame tube block and perform the “5-3-1.Projective Resolving Power Check”.
In case of OK, the adjustment is finished.
If NG, perform the adjustment below.
2.
Push the 5 group ball frame block in the direction of poor projection to reduce the gap.
3.
Confirm the optical axis. (Refer to section 5-4-1.)
In case of OK, check the projective resolving power.
If NG, perform the adjustment below.
4.
Push the 1 group ball frame tube block in the direction of center shift occurrence.
In case of OK, check the projective resolving power.
5-23
SAL70200G (2.8/70-200 G) (70-200mm F2.8 G)
5-4.
OPTICAL AXIS/FOCUS-SHIFT (FOCAL LENGTH)/FLANGE BACK (f’F) CHECK/
ADJUSTMENT
ADJUSTMENT
5-4-1. Optical Axis Check/Adjustment and Flange Back (f’F) Check
Equipment
• 1000 mm Collimator
• Flange Back Tester
• A-mount Attachment
• Flange Back Gauge (43.50mm)
1. Preparations
1)
Set the equipments as shown in the Fig.5-4-1.
Fig.5-4-1
2)
Looking through the eyepiece lens, turn the eyepiece ring of the flange back tester so that cross line or scale in the view is the sharpest.
3)
Attach the flange back gauge (43.50mm) securely to the A-mount attachment and hold them together.
4)
Turn the focusing knob of the flange back tester so that fine scratches on the flange back gauge (43.50mm) is the sharpest.
Note:
Turn the knob in the direction of the arrow of Fig.5-4-2 for correct reading.
Fig.5-4-2
5)
Turn the scale ring of the dial gauge until the long pointer indicates “0”.
Note:
This position is the flange back (f’F) = 43.50 mm.
Memorize the position of short-pointer.
flange back gauge (43.50mm)
A-mount attachment
Objective lens (10x)
Dial Gauge (Min. scale: 0.01 mm)
Scale ring
Eyepiece lens (7x)
Eyepiece ring
Focusing knob
Focus on fine lines on the surface.
Always turn the knob in the arrow
direction for correct reading.
direction for correct reading.
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