I am happy with most of my Canon equipment, but I have one complaint about their zoom lenses. The zoom action is too loose: if I have the camera on a tripod pointing down, e.g., to shoot a dinner plate, the lens falls to its fullest extension. There are easy fixes, such as chewing gum, but none seems to combine the convenience of slight adjustment and holding the focal length. A few of the good lnses, e.g., EF L IS II USM 100–400 f/4.5, have a "stiffness" control, but the shorter lenses do not. Does anyone else find this a nuisance?