Switch to Manual Focus mode
With your exposure settings dialled in manually, your camera will no longer change exposure values as you take your shots, so you’ll get a consistent level of brightness across the scene. To make sure the rest of the scene is consistent, set the White Balance to match the lighting conditions (eg Daylight, Cloudy, etc) and focus on an item about one-third of the way into the scene by half-pressing the shutter release button. With the focus set, now change to Manual Focus (MF) by flicking the switch on the camera body or lens to this position. This will keep your focus point at exactly the same distance in each shot you take as you sweep across the scene.