Zoom: Calculate your Field of View by adjusting the Focal Length, Crop, and Aspect Ratio. You can read the focal length off your lens. The crop is standared to the camera system/body you've chosen - 35mm film and top end DSLRs use 1; most mirrorless cameras use 1.54. If you don't know your aspect ratio, it's probably 4:3. You can calculate it by looking at your maximum resolution - 4:3 is a third wider than it is high.
Light: Once set up - by making adjustments with all locks open - close one or two locks and alter one of the locked attributes, or set you F-Stop reduction to match your filter, to make unlocked settings update. The light capturing ability of your camera will remain unchanged, within the restrictions of commonly avilable settings.