Sony DSLR-A300K (serv.man2) Service Manual ▷ View online
4-8
SAL1870 (3.5-5.6/18-70) (DT 18-70mm F3.5-5.6)
2. Adjusting Method
1)
Let the operation lever of the preset ring move to left and right sides by loosening two screws slightly to move to left and right sides.
2)
Move the two screws while seeing the lights from the rear lens element side, and tighten two screws at the point where the diaphragm
blades are hidden into the edge completely.
Fig.4-2-10
3)
Perform “4-2-1. Aperture Diameter Check” and repeat steps 1) to 3) until the aperture error is within the specification.
4)
After the adjustment is completed, apply the adhesive bond (B-10) to the two screws tightened in step 2).
Operation lever of the preset ring.
The diaphragm blades
are hidden into the edge
completely.
are hidden into the edge
completely.
Two screws
4-9
SAL1870 (3.5-5.6/18-70) (DT 18-70mm F3.5-5.6)
4-3.
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)
18
0.84
35
1.49
70
2.82
Table 4-3-1
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.4-3-1
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
4-10
SAL1870 (3.5-5.6/18-70) (DT 18-70mm F3.5-5.6)
2)
Attach the checking lens to the lens test projector, and set the equipments as shown in Fig.4-3-2.
3)
Turn the fan switch of the lens test projector to ON, then turn the lamp switch to ON.
Fig.4-3-2
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
4-11
SAL1870 (3.5-5.6/18-70) (DT 18-70mm F3.5-5.6)
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.4-3-3
3)
Turn the mount rotation ring of lens test projector until the projected image at a certain peripheral point (y’= 9 or 12) 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.4-3-4
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’= 9 or 12) at each focal-length (zoom) and distance is within the specification of the Table 4-3-2.
Specification
Focal-length distance (m)
Number of the smallest pitched lines
f (mm)
Center (y’=0)
y’= 9
y’= 12
(Lines per mm)
S
M
S
M
18
0.84
125
50
40
40
32
35
1.49
125
50
40
40
32
70
2.82
80
40
25
40
20
Table 4-3-2
5)
After the checking is completed, turn the lamp switch of the lens test projector to OFF and cool the inside of the lens test projector,
then turn the fan switch to OFF.
The number represents for lines per mm.
Saggital (S)
Meridional (M)
Correct resolution
Spurious resolution
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