Sony SAL1680Z Service Manual page 66

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'= 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.
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, 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)
f (mm)
35 1.4
80 3.2
SAL1680Z (Vario-Sonnar DT 3.5-4.5/16-80 ZA) (Vario-Sonnar T
Fig.4-3-3
Spurious resolution
Number of the smallest pitched lines
Center (y'=0) y'= 9 (Lines per mm)
(Lines per mm) S
125 or greater 63 or greater
125 or greater 63 or greater
Table 4-3-2
The number represents for lines per mm.
Saggital (S)
Meridional (M)
y'= 12 (Lines per mm)
M S
50 or greater 50 or greater
50 or greater 40 or greater
DT 16-80mm F3.5-4.5 ZA)
*
4-20
M
40 or greater
40 or greater