only on the 135 mm 'Soft Focus' prime lens, and enables a variable soft focus effect from completely sharp (0) to very soft (2), although it has little effect when used with apertures over f/5.6. Although the ring can be set to any position, two 'stops' are implemented at positions 1 and 2. Image stabilizer switch: This switch is found on all EF lenses that feature an image stabilizer. It is used for turning the image stabilizer "on"( | ), or "off"( o ). Image stabilizer mode switch: This switch is found on many EF lenses that feature an image stabilizer, particularly those of longer focal lengths. The switch has two settings on most lenses: Mode 1 and Mode 2. The newest IS Mark II versions of certain EF super telephoto lenses (the 300mm f/2.8L, 400mm f/2.8L, 500mm f/4L, and 600mm f/4L), plus the 200–400mm f/4L IS and 100–400mm f/4–5.6L IS II, have a third setting, Mode 3. Mode 1 is normal mode, used for typical photography, where the subject does not move. Mode 2 is used for panning; this is useful for sports or wildlife photography, where the subject moves constantly and one will need to pan. Mode 3, intended to track action, is similar to Mode 2 in that it ignores panning; however, it only applies stabilization when the shutter is released—the viewfinder image is not stabilized. One should not use Mode 1 for panning as this will typically cause blurred photographs; the image stabilizer will attempt to correct for all motion, including the panning motion, but cannot do so due to the limited range of motion of the IS mechanism. Older lenses that have an image stabilizer, but do not feature this switch, are permanently in Mode 1. Some newer lenses, such as the Canon EF-S 18-200mm lens, are able to detect if they are being panned in either axis and will automatically disable the stabilization for the axis parallel to movement and therefore do not require this switch. Autofocus stop buttons: These buttons are found on some super telephoto EF lenses, evenly spaced around the front collar of the lens. They are used for temporarily stopping the autofocus feature of the lens. Only one button needs to be pressed to activate the feature. To use this button, one must first have the autofocus active, then when one wishes to halt autofocus, one presses and holds the