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.
Always make sure that the tripod you are buying can handle at least twice more weight than your DSLR and lens. I have heard plenty of horror stories about expensive DSLR cameras falling off from crappy tripods! The best tripods are made by Gitzo, but they are expensive (starting from $400 and up).