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4. Reading the Graduations on the Focus Ring
(1) Read the value of the graduation where the zero point on the vernier scale indicates.
(2) Read the value of the graduation where the t wo lines are aligned straight on both the graduation on the focus ring
and the vernier scale.
(3) Put the above t wo values together to get a total.
Example 1
Vernier 0.02mm Increments
Draw tube 0.02mm Increments
Example 1: A total value is 24mm
(1) The line of zero point on the vernier
scale is aligned straight to the line of
24 on the graduations of the focus ring.
(2) The line of 0.2 on the vernier scale is
aligne d
s tr aight
to
a
graduation of the focus ring. The value
can be read as 0.00.
(3) The total value is 24 + 0.00 = 24.00
About the Vernier Scale
The vernier scale does not correspond with the zero point on the focuser draw tube.
The vernier scale can read the amount of drawing the tube in/out up to 0.02mm but the position of focus shif ts
according to environmental temperature where the VSD100F3.8 is used. When the draw tube is drawn in to the end,
the vernier scale may not come to an end at zero point because of this ef fect. Therefore, the vernier scale on the
VSD100F3.8 is designed to go across the zero point.
Reproduction of a Point in Focus
The travel of the focuser draw tube to a focal point varies with environmental temperature. Recording the readout of
the vernier scale and the corresponding temperature will be helpful in set ting the focus nex t time. It is recommended
that you turn the focus ring in the same direction when you reproduce the focal point with the vernier scale.
Example 2
Example 2: A total value is 24.10mm
(1) The line of zero point on the vernier scale
indicates a middle place between the
lines 24 and 24.2 on the graduations of
the focus ring.
line
on
the
(2) The line of 0.1 on the vernier scale is
aligned
graduation of the focus ring. The value
can be read as 0.10.
(3) The total value is 24 + 0.10 = 24.10
straight
to
a
line
on
the
6
Example 3
Example 3: A total value is 24.14mm
(1) The line of zero point on the vernier scale
indicates a place between the lines 24
and 24.2 on the graduations of the focus
ring.
(2) The line of 0.14 on the vernier scale is
aligned
straight
to
a
graduation of the focus ring. The value
can be read as 0.14.
(3) The total value is 24 + 0.14 = 24.14
line
on
the
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