How does the EF 70-200mm f/4L USM zoom lens perform on actual usage? I was not able to test it on any motorsports event since there were none during the time the lens was in my possession. As such, I am leaving out the AF's responsive time in this test. However, even without the chance of testing the zoom lens' ability of tracking moving subjects, I am confident of it accomplishing this on such occasions. Being a photojournalist who specializes in photographing motorsports, people, travel, portraiture and stock images, I do not hesitate in using any brand new product for an actual assignment even if I have not done a test roll with the item first. By my own calculations, these products should deliver what they are designed to accomplish, and I don't bother myself with "can it, should I or will it" questions prior to testing and using a new product. Although you have seen a photo of this zoom lens attached to a Canon EOS-lN pro model on the previous page, none of the images shown in this test was actually shot with that camera. Since this lens only has a maximum aperture of f/4, the EOS-3 was used instead for the test as it was capable of retaining the AF feature even with the Extender EF 2x attached. The lens will not be able to utilize its AF function with the 2x Extender if any other EOS model is used except for the new EOS-lv pro model. The zooming action is smooth and quick. With the EOS-3 set on Program AE mode and 21 -zone Evaluative metering, I was able to shoot a scene at the lens' 70mm setting and zoomed immediately to the 135mm position for the next shot. The two photos are shown below. No exposure compensation was necessary with both shots which were photographed at dusk. A commercial district (70mm) Same district (135mm) This is the third Canon EF zoom lens that is able to use both the EF Extender 1.4x and 2x, after the EF 70-200mm f/2.8L USM and the EF 100-400mm f/4.5-5.6L IS USM. Autofocus is possible with this lens when the EF 1.4x is attached and used with any EOS model. For AF to work (only with the center AF point) with the 2x, you will need to use either the EOS-3 or the new EOS-lv pro model to achieve it. At 70mm At 100mm At 135mm At 200mm At 270mm (135mm x 2) At 400mm (200mm x 2) Surprisingly, the AF function is quite fast even with the Extender 2x attached, although only the EOS-3's center point works in this arrangement. The inclusion of the inner focusing and Ring USM results in high-speed, silent autofocusing. Using the focusing range limiter switch, the AF search time can be dramatically reduced. << Back to Main . 1 . 2 . 3 .