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.
Re: tripod with your long lens. For my 800mm I use a Gitzo carbon fiber tripod with no center column. You need one that is rated at double the actual weight of camera/lens/head but don't go overboard as its all extra weight to carry. If you have no stabiliser that works on the tripod, you need a higher rated tripod.