The 1999 Proton Merdeka 300 Km Endurance Race gave me the opportunity of not only testing the EF 100-400mm lens' dual-mode of Image Stabilizer feature but also the chance to gauge its optical quality as well. With such a wide range of the most popular telephoto focal lengths, it was easy for me to shoot candid portraits and the racing event with just one lens. I didn't even need to use my other EF lenses at all. Horizontal candid portrait Candid shot of Team Hi-Rev girls How well does the IS system work, anyway? For those people whose hands are steadier than others, they will find little difference in their photos shot with and without the Image Stabilizer mode being switched on. Sometimes, even I find myself to be very steady when slow shutter speeds were used for handheld shots. For example, can you find any difference between these candid portraits, one was with IS off and the other is with the IS switched ON, as shown below? Candid portrait, IS off Candid portrait, IS on Since the 300 Km endurance was a long affair, just for the fun of it, I decided to shoot some of the racing Proton cars with a slow shutter speed of 1/30 sec at the 40mm focal length setting without the IS feature being switched on. The results? There is evidence of camera shake and slightly blurred images of the car, as shown in this three-picture sequence: (but your Windows PC or Mac monitor may not show it clearly) IS Mode 1 was used for this shot For the vertical format shot (above), the IS Mode 1 was used mainly because I was waiting for the cars approaching the chicane rather than following them via panning. The result (yellow car is the main subject), with a shutter speed of 1/160 sec. is very good, no camera shake. << Back to Main . 1 . 2 . 3 . 4 . 5 .