Standard Video Controls
mechanical iris
5.2 Mechanical Iris
Only a relatively small portion of the light which passes through the film camera´s lens goes to the CCD chip of the video assist, as the light is shared between the viewfinder, the CCD chip and the film. Therefore the IVS lenses are designed for normal usage with a totally open iris to have maximum light on the CCD chip. Variations in lighting are compensated by the IVS gain control (automatically or manually).
Under certain conditions, such as when lighting is set for low sensitivity film (under 100 ASA) or for motion effects, it is possible that the IVS gain range is exceeded. In this case the mechanical iris of the IVS lens can be closed.
Check all settings on the connected monitor.
If the mechanical iris is closed more than necessary, the IVS will compensate by increasing the gain and improve the image brightness electronically. This creates additional electronic noise.
To avoid this, always open the mechanical iris as far as possible.
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