Sony SAL24105 Service Manual page 71

Ver 1.3 2007.07
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).
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.
Do not confuse spurious resolution for the smallest pitched lines.
Correct resolution
Fig.4-3-4
4) Change the focal-length (zoom) and distance of the checking lens, and check that the all readings (y'= 0, y'= 12 (f=24, meridional
(M) only) saggital (S) and meridional (M) at y'= 15 or 18) at each focal-length (zoom) and distance is within the specification of the
Table 4-3-2.
Specification
Focal-length distance (m)
f (mm)
24 1.1
50 2.0
105 4.0
SAL24105 (3.5-4.5/24-105) (24-105mm F3.5-4.5)
Fig.4-3-3
Spurious resolution
Center (y'=0) y'= 12 (Lines per mm)
(Lines per mm) S
125 or greater —
125 or greater —
125 or greater —
The number represents for lines per mm.
Saggital (S)
Meridional (M)
Number of the smallest pitched lines
y'= 15 (Lines per mm)
M S
25 or greater 40 or greater 32 or greater 25 or greater 25 or greater
— 40 or greater 32 or greater 40 or greater 25 or greater
— 40 or greater 25 or greater 40 or greater 25 or greater
Table 4-3-2
4-20
y'= 18 (Lines per mm)
M S M