SAL18135 - Sony Digital Camera Service Manual (repair manual). Page 17

4-5

SAL18135 (3.5-5.6/18-135 SAM) (DT18-135mm F3.5-5.6 SAM)

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 sharp-

est.

3)  Attach the flange back gauge (43.50 mm) 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 (43.50 mm) is the sharpest.

Turn the knob in the direction of the arrow of Fig. 4-3-2 for correct reading.

 

Focusing knob

Focus on fine lines on the surface.

Always turn the knob in the arrow
direction for correct reading.

5)  Turn the scale ring of the dial gauge until the long pointer indicates  0 .

This position is the flange back (f F) = 43.50 mm.

 

Memorize the position of short-pointer.

1)  Attach the checking lens to the flange back tester, and set the 1000 mm collimator.

 

1000 mm collimator

Checking lens

2)  Set the focus ring of the checking lens to 

∞

 (infinity) index or near 

∞

 (infinity)  and adjust the optical axis, observing the microscope 

so that the chart can be seen in the center.

3)  Turn the focusing knob of the flange back tester until the chart image comes into focus.
 

Also check the optical axis aligns with the chart center. (Refer to Fig. 4-3-4.)
Note: 

Figure shows example. The cause depends on individual lens.

 

Optical Alignment
Best alignment

Incorrect aligned
e.g. As the focusing knob is turned, the chart may appear blurry as illustrated.
The cause depends on individual lens.

4)  Perform Step (1) through Step (6) and ensure that the AS and CB values are within specifications. 

  If the specification is  CB  only, steps 1 to 3 are not required.

 AS 

(astigmatism)

 

The phenomenon where the flare on the ring chart appears in a cruciform shape with the ring chart in the sharpest focus. (Fig. 4-3-5 (a))

(1)  Turn the focusing knob until the flare becomes minimum between two approximately opposite points on the ring chart edge (as 

shown with the arrows in Fig. 4-3-5 (b)), and then read the dial gauge value. <A>

(2)  Turn the focusing knob until the flare becomes minimum between two points with the phase of the flare rotated by 90 degrees 

from the above condition (as shown with two arrows in Fig. 4-3-5 (c)), and then read the dial gauge value. <B>

(3)  Calculate the AS value (absolute difference between <A> and <B>) and ensure that it is within specifications.
 

AS value = <A> - <B>

 

CB (Center Blur)

 

The phenomenon where the flare on the ring chart trails in one direction with the ring chart in the sharpest focus. (Fig. 4-3-5 (d))

(4)  Turn the focusing knob until the ring chart edge in the direction of the maximum flare is in the sharpest focus (as shown with 

the arrow in Fig. 4-3-5 (e)), and then read the dial gauge value. <C>

(5)  Turn the focusing knob until the ring chart edge, opposite 180 degrees from the above condition (as shown with the arrow in Fig. 

4-3-5 (f)) is in focus, and then read the dial gauge value. <D>

(6)  Calculate the CB value (absolute difference between <C> and <D>) and ensure that it is within specifications.
 

CB value = <C> - <D>

 

(1)

(1)

(2)

(2)

(5)

(4)

AS

E

D

F

H

G

I

CB

CB (center blur)

0.19 mm or less

AS (AS on the axis)

0.14 mm or less

5)  If the specifications of CB and AS are not satisfied, perform the  4-3-2. Optical Axis Adjustment .

1.  If the optical axis does not meet the specification, replace the following parts.

①

  A-1849-455-A 

1ST LENS ASSY

②

  A-1849-503-A 

OPTICAL BLOCK FOR SERVICE