Make the aperture (the hole in the lens) small by turning the wave wheel to the right. The wave wheel is located in front of the camera and beneath the “Off/On” button. Turn the wheel until it reaches “F16” on the screen.

Confirm the Location of the Stain: Press the shutter against a plain white surface and take a picture. If the camera sensor has dust or debris covering it, then there will be darker spots on the image.