Common skin warts (also called cutaneous warts) are raised round or oval growths. A wart may be lighter or darker than the skin around it. Some warts may have tiny black dots in them, often called seeds. The dots are small, clotted blood vessels. Warts may occur alone or in larger groups that merge and form patches.
According to Canon (link):  Canon addressed the âfeedback loopâ in later model IS lenses by introducing an algorithm to the IS detection system to automatically recognise when the lens is mounted to a tripod.
1 Place your camera on tripod so the center of the lens is level with the center of the test target. 2  A laser pointer held along the lens barrel can be used for targeting and to confirm centering. 3  A bubble level (built into the tripod or a more accurate hardware level) confirms the lens is lined up vertically.