Reviews

How good is the image stabilization in Canon's 100-400mm f/4.5-5.6L IS USM lens?

 

Canon 100-400mm Lens

Canon's 100-400mm f/4.5-5.6L IS USM is a very popular lens, certainly one of the largest selling of the L series lenses. It seems like a lens has to be a zoom to sell in quantity in today's market. Canon also makes a fixed focus 400mm f/5.6L lens. Canon probably sells one tenth the number of the 400mm fixed lenses as they do the 100-400mm zoom, even though the zoom is optically inferior. See Michael Reichmann's comparison of the optical quality of these two lenses. One would think, therefore, that the 100-400mm zoom has something else going for it. Image Stabilized (IS) lenses are very sexy these days, and the inclusion of IS in this lens certainly adds to its appeal. Of course, zoom lenses in general have more sex appeal than fixed focus lenses, even though they are optically inferior, in general. The thing with the 100-400mm zoom is that most folks use it almost entirely at 400mm. That being the case, the one advantage the zoom has over the fixed 400mm is the IS capability. The IS capability is said by Canon and others to confer at least a 2 stop advantage. However, I have never seen any data supporting this statement. Therefore, I set out to test just how good the IS is in the 100-400mm lens.

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The Test

I wanted to be able to test the sharpness of photos taken at different shutter speeds. The easiest target for this purpose is printed material, as it is very easy to compare sharpness of one photo to another. I set up Kodak's Color Darkroom Dataguide in my front yard. Don't ask me why I still have it around. Ok, I'm a packrat. I set the Dataguide against a palm tree and took a series of photographs at different shutter speeds from a distance slightly less than 50 ft, handheld. The lens was set at a focal length of 400mm for all tests. I used the following shutter speeds: 1/2000, 1/1000, 1/500, 1/250, and 1/125, with and without the IS. I repeated this series 4 more times. As this test was performed over 4 years ago, I did the test on Velvia 100 slide film with a Canon Elan 7nE camera, and then scanned the slides in a Nikon LS-5000 slide scanner.

The result from all of tests showed that the IS in this lens will allow only a 1 stop decrease in shutter speed. Hand holding the lens without IS, I was able to get pictures sharp at 1/500 sec, but not at 1/250 sec. With the IS on, I was able to get sharp photos at 1/250 sec, but not at 1/125 sec. Below you can see the results of one series:

Canon 100-400 Lens test

Canon 100-400 Lens Test

Canon 100-400mm Lens Test

Canon 100-400mm Lens Test

Canon 100-400mm Lens Test

Canon 100-400mm Lens Test

Considering the results of this test, and other tests of its optical performance, one has to ask the question, what is this lens good for? I think it is good for two things. First, if you have to have a zoom in this focal length range, then this is the only one in the Canon lens line. The other advantage of this lens is its relatively small size for travel. My 400mm f/5.6L lens, while small compared to the f/2.8 version, still takes up a lot of my backpack. The 100-400mm zoom is much more compact.

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What this zoom is not particularly good for is nature photography. The 400mm f/5.6L is far superior for that purpose, being optically much sharper, and it also focuses much faster. Come on, Canon, get off your butt and redesign this dinosaur. It's long overdue. With the latest generation of IS and an improvement in the optics, this would be a great lens to have.