I had a chance to play with Canon’s affordable 100-400mm L series zoom last week. I rented it for a day from Penn Camera at Tyson’s Corner, mounted it on my 5D, and ran out to chase wildlife as soon as I got home from work. As the sun began to set, I took it up to the roof, set it on my tripod, and took photos of the horizon. In the morning, I snuck out onto the terrace at sunrise and got photos of that as well. All in all, I put the lens through its paces, shooting in daylight, dusk and dawn conditions, handheld and on a tripod. Even though I only used the lens for a day, albeit a pretty full one, I’m fairly comfortable with what I’m about to say.

I liked it. The 100-400mm range is a versatile range, and the fact that you can get this L series lens at around $1,400 makes it a bargain. The lens isn’t as heavy as the 70-200mm L series zoom (which I played with today), and it’s fairly comfortable to hold for moderate amounts of time. It has a push-pull mechanism for extending the focal range, and that has its benefits and drawbacks. The benefit is that it does make it a bit easier to get through the large focal range a little faster. It’s also necessary in order to make the lens affordable. Push-pull lenses are cheaper to make than regular zooms, and require less glass as well, making them lighter.

➡ Updated 7/4/07: Erik Persson asked me two relevant questions this morning via private email. One is about how the autofocus handled, and the other was about whether autofocus is possible at all with an extender, or whether manual focus needs to be used. Autofocus was a bit slow, but that’s to be expected. This is a big zoom that can focus over a large distance. There is a focus limiter switch that decreases the focusing distance. You tell it to focus either from 1.8m to infinity or 6.5m to infinity. If you know you’re only going to shoot things farther away than 6.5m from you, then set the switch to that, and the autofocus will be a little faster. I’m not sure how to answer Eric’s second question. He suggests autofocus on EOS models up to the 5D is possible only up to f/5.6, and Mark 1D models can autofocus up to f/8.0. Not sure about that. I can only point you to this lens chart at Canon, which talks about the compatibility of the extenders with various lenses, and tells you what the expected aperture will be, and whether or not autofocus will be possible at all. I checked the specs for the 5D and 1Ds, and can’t find the upper f-stop limits for either models. Perhaps a call to Canon will clear this up, but it is the 4th of July today, and I doubt they’re open. Maybe one of you who has more information is willing to comment on this.

➡ Updated 7/6/07: Erik got back to me once more with a link to a review by The Digital Picture, where the AF to aperture specs are discussed. Furthermore, he provided a link to specs from Canon for the EOS 1v SLR (film camera) where the bit of information about being able to use AF with lenses that only open to f/8 is provided. So it looks like you’ll have to use manual focus if you stick extenders on the 100-400mm zoom. Thanks Erik! You know, you could just as well use the comments instead of sending me emails, but whatever works for you. 🙂

If you’ve been looking at the 400mm f/2.8L tele, which retails around $6,500, and you’re wondering why this lens is so inexpensive, you should know there is a reason for the price difference — but I doubt you needed me to tell you that. I stated the reasons in the paragraphs above, and they are: less glass, push-pull mechanism for the EF 100-400mm zoom lens. I haven’t tried out the 400mm tele myself yet, but I have a feeling it’s a great deal sharper and has more contrast than this lens.

I think you can already guess what my two complaints are: the details are a bit soft when the photos are viewed at 100%, and the push-pull mechanism creates a sort of vacuum between the camera and the innermost lens. Every time I extended or contracted the lens, air rushed in or out through the crevices. I’m sure things are isolated pretty well and dust doesn’t get sucked in, but it feels odd, and it makes it difficult to stop at say, 300mm. It’s certainly a lot easier to either pull the lens all the way out to 400mm or push it all the way back in to 100mm. You know how they say that zoom lenses are soft at either ends of the focal range? Well, it would have been nice to have some sort of limiter switch that could let me stay between 110-390mm, or something like that. With the push-pull mechanism, it was hard to get the focal length just below or above its limit in order to avoid softness.

Having said all this, let me reassure you that this lens is a bargain at its price. If you’ve had your eye on it, get it. Realize you won’t get the results you might get with a more expensive tele, but you won’t pay through the nose for it either. This lens will definitely shine on cropped sensors like those found in the 30D and Rebel, where the effective focal range will be 160-640mm. How else can you get in the 600mm focal range without spending a ton of money? What’s more, with extenders like the 1.4x or the 2x, you can get up to 800mm on a full sensor or up to 1260mm on a cropped sensor. That’s pretty amazing!

There are a few other things to keep in mind though. The maximum aperture at 400 mm is f/5.6, and that means you’ll need pretty good light in order to shoot handheld with it. If you stick an extender on it, the effective aperture will get even smaller, so you’ll either need serious daylight or a tripod. But, as I’ve already said, you get amazing range with this lens, and it’s inexpensive for an L series zoom. If you’re willing to live with the few issues I’ve outlined, then get it.

Buy the lens

• EF 100-400mm f/4.5-5.6L IS USM specs on Canon website
• EF 100-400mm f/4.5-5.6L IS USM listing at Amazon
• EF 100-400mm f/4.5-5.6L IS USM listing at B&H Photo