tcchou71's Full Review: Canon EF 100-400mm f/4.5-5.6 IS USM Lens
Note: I originally reviewed this exact product two years ago, and it has been one of my more popular reviews. For some reason, the original review disappeared from Epinion's search engine results. Hence, I've resubmitted it with minor corrections and clarifications. At least three of my lens reviews have disappeared like this over the last year - what's going on?
Thank you for your consideration, and now for the review:
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This lens generally gets highly favorable reviews. The combination of sharpness, image stabilization (IS), and fast autofocus make it very versatile, even for demanding subjects like wildlife. However, it isn't perfect, and if you're going to pay $1400 for a lens, you should also be aware of the shortcomings, and how they compare with other lenses in its class. The major shortcomings are:
(1) Sharpness declines slightly at 400mm. Not everyone reports this, so I sent mine to Canon, in case something was miscalibrated, but it didn't help. I think one has to expect that even the best zooms are going to be slightly less sharp than a prime of the same focal length/aperture. Otherwise, there would be no reason to buy primes. (2) The zoom lock ring is joined to the focus ring, and requires two hands to operate. It is almost impossible to lock/unlock the zoom without knocking the focus wildly out of whack. (3) The IS is first generation, not the improved version on Canon's latest lenses. (4) This lens is expensive compared to the other zooms in its class.
I wanted to use this lens for wildlife photography, including flying birds, so I compared it with three other zooms that reach 400-500mm: the Sigma 80-400 OS, Sigma 50-500 EX, and Tamron 200-500 SP. I tested 3 copies of the Canon, 2 copies of the Tamron, and 1 each of the Sigmas, all on a Canon rebel 300D.
Although I chose the Canon 100-400 over all the other lenses, it was not a slam-dunk case. The Sigma 80-400 OS seemed a tiny bit sharper than the 100-400 at the all-important 400mm limit, its optical stabilization (OS) was just as effective as Canon's IS, and its additional wideness (80mm vs 100mm) was surprisingly helpful. The Sigma was substantially cheaper than the Canon lens, so I would have kept it if not for its veerrry sloooow autofocus ... much too slow for flying birds or most other moving objects.
The Sigma and Tamron 500mm zooms had significant resolution advantages over the 100-400 L. Although 500mm may not seem like much more than 400mm, the difference is noticeable if you have a very distant object, and must crop/enlarge the photo. This is because pixel coverage increases with the square of focal length. Zooming from 400mm to 500mm increases pixel coverage by 25/16, a 56% gain. That's like upgrading your camera from 8MP to 12.5MP. Of the two 500mm zooms, I was particularly impressed by the Tamron 200-500mm, as it was reasonably sharp (though slightly less so than the Sigma 50-500), and impressively light, at only 2.7 pounds, much lighter than the Sigma 50-500 (over 4 pounds), and even a tad lighter than the 100-400. The Tamron's barrel was narrower than the other lenses, making it easier to handhold. Although plastic (whereas the Sigma and Canon are metal) the Tamron was well constructed, and had a metal mount. However, the Tamron's autofocus, albeit faster than the glacially slow Sigma 80-400, still had considerable trouble with backlit flying birds, unlike the Canon lens.
The Tamron's focus motor was actually almost as fast as Canon's, but it lacks the Canon's autofocus limiter, which makes a huge difference. When engaged, the focus limiter cuts search times in half, simply by blocking out the near end of the lens's focus range.
If the Tamron 200-500 only had a focus limiter, I would have chosen it over the 100-400, due to its longer reach, lower weight, and lower price. I found the Tamron to be surprisingly hand-holdable for bright sunlit objects, and in bright daylight I did not miss the image stabilization.
As for the Sigma 50-500, its autofocus was faster than the Tamron, but my copy consistently back-focused at 500mm, and I could only get a crisp shot using manual focus. This was tragic, but not surprising - I've seen many optically sharp Sigma lenses that focus poorly on Canon DSLR bodies.
In the end, the Canon 100-400 was a compromise choice; it was not the sharpest, lightest, or longest lens, but was the runner up in all three categories, and its fast, accurate focus and focus limiter switch boosted it ahead of its rivals.
Should you get the 400mm f/5.6 L instead? After using the 100-400mm for a year, I have mixed feelings about its role for wildlife. In the 100-300mm range, it's fantastic. But around 400mm, its sharpness declines enough to be frustrating if you have to crop and enlarge a lot. Also, 400mm is not enough zoom for very distant subjects, especially birds.
If you are thinking of extending the 100-400's reach with a 1.4x teleconverter, forget it. Yes, your pictures will get larger, but the sharpness will decline further, negating most of the gain in pixel resolution. Hand-shake and focus errors will increase, further offsetting the teleconverter's small gain in resolution.
Because I use this lens at 400mm so often, I now realize that Canon's fixed-focal-length 400mm f/5.6 L would have been more useful. It is sharp wide open at 400mm, and still sharp with a 1.4x teleconverter. It is also cheaper than the 100-400. It lacks IS, thus requiring a tripod or monopod in weaker lighting, but for distant subjects, there is no substitute for a sharp long lens.
Focus issues put the Canon ahead of the others All the zoom lenses I tested were optically on par with each other, except for the Tamron which lagged slightly behind due to is lesser sharpness and greater purple fringing. But what really distinguished the Canon lens was its focus-limiter switch and fast accurate autofocus, which have been very useful for the abundance of flying birds we have out here in California. Sigma and Tamron will have to improve autofocus speed/accuracy to compete with Canon in the wildlife photography area.
Although many people complain about Canon's notorious push-pull zoom, I like it, as it makes it easy to find the subject (at low zoom) then quickly take a shot (at max zoom). But as many people have noted, the zoom tightening ring is just bizarre. It is joined to the focus ring, needs two hands to operate, and causes the focus to change whenever the zoom is tightened or loosened. I'm mystified why Canon doesn't separate the focus and zoom lock rings as there is no reason for them to be linked.
Interestingly, the Tamron 200-500mm can be used as an ad-hoc push-pull zoom. Simply grab the front of its barrel and pull - it will slide smoothly back and forth, and works better than the Canon lens in this regard, as you can change the zoom quickly without knocking the focus out of whack.
Summary In the end, I recommend the Canon more than the other lenses, but not without reservations. If you mostly need the 100-300 range, and only occasionally use 400mm, and need the Canon's fast autofocus, this lens will give you the best performance money can buy. However, for wildlife, you'll find yourself using 400mm quite often, where this lens is weakest. In that case, you should consider a 400mm prime lens. The 400mm f/5.6 L is superb, but there are other good choices too.
If you don't need the Canon's fast autofocus, the Sigma 80-400 OS is just as sharp, has an extra 20mm at the short end, and is substantially cheaper. And if you don't need the image stabilization you should look at the Tamron 200-500, which is relatively lightweight and inexpensive, and has good optics (except for purple fringing, which is partly correctable in Photoshop).
I cannot recommend the Sigma 50-500 because of the focus issues I've had with it. However, this may vary between lenses and camera bodies. For example, I've read anecdotal evidence that this Sigma lens focuses somewhat better on Nikon bodies than on Canon bodies.
In the years since I wrote this review, Sigma has released several more long telephoto zooms. The most interesting is the 150-500mm OS HSM. I haven't tried it personally, but it is heavy (over 4 pounds) and seems prone to autofocus incompatibilities on some Canon bodies, like the 50-500 I tried. I found a pretty good review about that lens here:
http://www.michaelfurtman.com/sigma150_500.htm
This guy specializes in wildlife photography, so his comments are highly relevant.
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