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(5-2) Setting of shutter speed
The shutter speed is determined mainly by the shutter switch position from “0” to “9”.
When a shutter speed is specified using a communication command, the communication command is prioritized.
The shutter speed to be displayed is the one that is corresponding to the currently selected shutter switch position. When
“7” is selected for the mode switch, the current shutter speed can be changed.
(Note) The change of the shutter speed is enabled only when the shutter switch is set to any positions other than “0”.
As long as the shutter switch is positioned at “0”, the shutter speed cannot be changed even if “7” is selected for the
mode switch and the UP/DOWN switch is manipulated. (The shutter is always OFF where the shutter switch = “0”)
(5-3) Level setting
The level setting is mostly divided into the following
two groups:
●
Gain setting
This is to set the gain (amplification ratio) of the
preamplifier between the CCD imaging device
inside the camera
→
A/D converter.
●
Offset setting
This is to set the offset of the preamplifier between
the CCD imaging device inside the camera
→
A/D
converter.
→
Refer to the next section (Section 6) for the
specific setting method.
(Note) As for the offset setting, it is recommended to
use the factory default setting except for a
special case.
(Note) Follow the procedure (gain setting
→
offset
setting) if fine tuning of the offset value is
required.
(5-4) Gain setting of preamplifier
●
Gain variable amplifier and integrated gain
The image signal output from CCD is amplified inside the
camera through the fixed gain amplifier on the anterior
stage and then through the following variable gain amplifier
before being input into the A/D converter.
The left block chart shows this flow.
(Note) The gain value (dB) described here is the one based on
the CCD output (0 dB) as the baseline.
●
Correlation between MGC gain setting value and MGC gain
This equipment is controlled by giving the MGC setting
value. The correlation between this setting value and
the MGC gain (integrated gain including the gain of the
variable gain amplifier and that of the fixed gain
amplifier) is shown in the right graph.
(Note) When the CCD element receives excessive light
with a low gain value of the amplifier due to the
restriction of the dynamic range of the CCD light
receiving element, the signals of the nonlinear
area of the CCD element and the preamplifier
are output at the high brightness area.
In this state, unnatural image (Note below) may
appear in the neighborhood of the saturating
signal area of the image due to the
characteristic of the nonlinear area. This
phenomenon, which is associated with the
saturation characteristic of the CCD element, is
not a failure arising from the camera.
Signal level
V ideo wavef orm
(B efore setting adjustment)
Increase in GAIN
Increase in OFFSET
S ignal level
S ignal level
Output
system
Left side of
screen
Right side of
scr een
Output
system
Left side of
screen
Right side of
screen
SINGLE GAIN setting value
SINGLE OFFSET setting value
DUAL
DUAL
OFFS ET s ett ing v alue
+ OFFSE T B s etti ng
val ue
GAI N sett ing val ue
+ GAI N B set ting
v alue
Ｃ Ｃ Ｄ
Preamp lifier
Ａ ／ Ｄ
Ｇ ＡＩＮ
Var iable gain amplifier
0dB
（
Fixed
）
Integrated ga in
MG C sett ing
Fixed gain amplifier
MGC GAIN CODE
M
G
C
G
A
IN
(d
B
)
10
20
30
40
20
40
60
80
A0
C0
E0 (hex)
32
64
96
128
160
192
224 (dec)
Fig. 5-2 Conceptual diagram of gain and offset levels
Fig. 5-3 Gain setting
Fig. 5-4 Gain characteristics