Visual Assistant (v.1.8) Software User Guide
Edit light
Menu Tool 
If using the dialog boxes, by selecting the 'light' option you will get:
Explanation:
There are five options that you can set:
light on / off Will switch the light filter on or off. This can also be done from the menu item Lights. The light filter will be automatically switched on when you use the move light tool. light colour Will invoke the colour picker so that you can choose a colour for the light. light shape Choose between a perfectly round light and an ellipse (in which the height is half the width). light angle (or size) There are five settings to choose from, varying from a very wide-angle light on the left, to a very narrow-angled light (i.e. a spot light) on the right. light concentration There are five settings to choose from, varying from a very diffuse light on the left, to a very concentrated light on the right. .