70-300MM

Sporting a 3rd generation image stabilizer, the Canon EF 70-300mm f/4-5.6 IS USM Lens is designed to be handholdable at a shutter speed up to 3 f-stops slower than a non-stabilized lens at the same focal length. “Gyro sensors detect unwanted vibrations, triggering the corresponding movement of a correcting lens group perpendicular to the optical axis. This alters the light path, returning the image to its correct position on the sensor or film plane.” [Canon]

Using the 1/(focal length) rule, this lens can be handheld at 300mm with a shutter speed of 1/45 of a second (of course, your mileage may vary). I am getting sharp handheld images consistently at 1/4 or 1/5 second shutter speeds at 70mm and at 1/25 second at 300mm on a full frame body. All of the 70-300 IS sample pictures (link below) were taken handheld.