Functions

Functions

Gain

Both Manual and Auto Gain settings are available with this camera.

The variable range extends from 0 to 24 dB for the black and white models or from 0 to 18 dB for the color models. The camera is designed so that the gain can be subdivided and set by 0.0359 dB.

At the factory default setting, the gain is set to 0 dB. When Auto Gain is selected, the gain is adjusted automatically, based on the brightness of the subject. At this time, the reference level (target point) is set in the AutoExposure register.

For details on AutoExposure, see “Auto Exposure” on page 9.

Shutter

This camera allows both Manual and Auto Shutter settings.

The variable range extends from 10 microseconds to

16.0seconds; relative values are indicated by a 12-bit integer, and absolute values are indicated using a 32-bit floating point value.

The relationship between the parameter and the exposure time is given by the following formulas, where:

P = Parameter (003h to 47Eh) E = Exposure time (s)

If P= 3

E = 0.00001

If 4 <= P <= 1000

1

If 1000 <= P <= 1150

Setting examples

3 (003h) : 10 µs (1/100000)

32 (020h) : 1 ms (1/1000)

100 (064h) : 10 ms (1/100)

1000 (3E8h) : 1 s

1010 (3F2h) : 2 s

1150 (47Eh) : 16 s

16 s

2

1 s

1

10 µs

3

1000

1150

When Auto Shutter is selected, the exposure time is adjusted automatically, based on the brightness of the subject. At this time, the reference level (target point) is set in the AutoExposure register.

For details on AutoExposure, see “Auto Exposure” on page 9.

For long exposure times

When the exposure time is longer than the frame period, the camera enters the long exposure time mode, and the actual frame rate is reduced in accordance with the exposure time.

Absolute Value Control for the Shutter

This camera allows control of exposure time using absolute values. The values are indicated using a 32-bit floating point value. (Unit: sec.)

The variable range of absolute values extends from 10 microseconds to 16.0 seconds.

Programming example union

{

DWORD dwValue; // 1394 is expressed in quadlets, float fValue; // exposure time is indicated in seconds.

} AbsoluteShutterValue;

AbsoluteShutterValue.fValue = Exposure time; WriteQuad(AbsoluteShutterOffsetAddress, AbsoluteShutterValue.dwValue);

WriteQuad is a virtual function used to write in the 1394 register.

AbsoluteShutterOffsetAddress is an offset address for the absolute value control.

See “ConfigurationROM” on page 17 for the formula for the offset address.

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