Sets the TV focus.
2=to: 2!:}Format: TVFOCUS <focusvalue>
2=to: 2!:}Example: TVFOCUS 15000
2=to: 2!:}Units: Microns.
2=to: 2!:}Range: 0 to 17500.
2=to: 2!:}Comments: To adjust the TV focus so that the TV is focussed on the slit, or so that a star is in focus on the TV in direct mode.