Sony DSLR-A300X / DSLR-A350X / SAL55200 Service Manual ▷ View online
4-21
SAL55200 (DT 4-5.6/55-200) (DT 55-200mm F4-5.6)
4-4.
PROJECTIVE RESOLVING POWER CHECK/ADJUSTMENT
4-4-1. Projective Resolving Power Check
Equipment
• Lens Test Projector and Variable Transformer (Output voltage: AC 100 V)
Note:
Connect the variable transformer (Output voltage: AC 100 V) to the lens test projector.
• A-mount Attachment
• Screen (Art paper)
• Tape Measure
• Plane Mirror (For SLRs)
1. Preparations
Note:
Note:
Check the projective resolving power of the checking lens at the following focal-length and distance.
Focal-length f (mm)
distance (m)
55
3.63
131.2
7.97
200
11.90
Table 4-4-1
1)
Perform the following steps (1) to (3), and incorporate the internal lenses of the lens test projector according to the checking focal-
length.
(1) Open the lid of the lens test projector.
(2) Pull up and turn the fixed levers on the right and left sides of the lens test projector.
(3) Remove or insert the lens.
Note:
Be sure to have the right position and direction of the lens.
Fig.4-4-1
Lens test projector
Incorporate of the lenses
according to the checking focal-length (f).
according to the checking focal-length (f).
Lens
Fixed lever
Fixed lever
Lid
f=18 to 35 mm
f=35 to 100 mm
f=100 to 200 mm
f=200 to 300 mm
Heat-absorbing filter
Chart
Chart
Chart
Chart
Filament
Filament
Filament
Filament
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SAL55200 (DT 4-5.6/55-200) (DT 55-200mm F4-5.6)
2)
Attach the checking lens to the lens test projector, and set the equipments as shown in Fig.4-4-2.
3)
Turn the fan switch of the lens test projector to ON, then turn the lamp switch to ON.
Fig.4-4-2
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
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SAL55200 (DT 4-5.6/55-200) (DT 55-200mm F4-5.6)
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’= 9) 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.
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’= 9) at each focal-length (zoom) and distance is within the specification of the Table 4-4-2.
Specification
Focal-length distance (m)
Number of the smallest pitched lines
f (mm)
Center (y’=0)
y’= 9 (Lines per mm)
(Lines per mm)
55
3.63
80 or greater
40 or greater
131.2
7.97
80 or greater
40 or greater
200
11.90
80 or greater
40 or greater
Table 4-4-2
The number represents for lines per mm.
Saggital (S)
Meridional (M)
Correct resolution
Spurious resolution
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SAL55200 (DT 4-5.6/55-200) (DT 55-200mm F4-5.6)
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.
• The following projective resolving power adjustments 1 and 2 meet the specifications respectively.
1. Projective Resolving Power (Partial Blur) Adjustment
Check the projective resolving power. Conform the following adjustment if necessary.
1)
Remove the zoom rubber.
2)
Set the focal length of lens to 200 mm.
3)
Inserting the screw in the hole of zoom ring, install the screw to the 2nd lens barrel.
Screw
Part No.
Description
3-279-371-01
SU2.6X2.5C3C
Table 4-4-3
4)
While observing the screen, adjust the partial blur by screwing in with the quantity of forward focus.
Note:
Adjust with 1 - 2 screws.
Install the screw using the hexagon wrench (1.27 mm).
Fig.4-4-5
Screw
Screw
Screw
Zoom Rubber
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