Near each wheel is shown the aperture number (from 1 to 8). During a movement, from one to an other position, the wheel image start to rotate showing that BFOSC is in a non-operative state.
It is not possible to start an exposure if the wheels are moving.

The number on the right of the camera image is the value of the camera focus.
The last symbol on the window shows a rapresentation of what the CCD should "see" in the current instrument configuration (sky, sky behind a slit, spectrum). This in order to help the user to understand the instrument operative state.

The last image shows the shutter status (open or close).