SLRgear Review September 9, 2009 by Andrew Alexander This venerable successor to the 80-200mm ƒ/2.8L employs a complex optical formula of 18 lens elements in 15 groups, with 4 elements being ultra-low dispersion glass. The lens is a constant ƒ/2.8 lens, compatible with full-frame cameras. On a digital body with an APS-C sized sensor, the lens will produce an effective field of view of 112-320mm. The 70-200mm EF ƒ/2.8L USM ships with a case and petal-shaped lens hood, takes 77mm filters. Sharpness The Canon 70-200mm ƒ/2.8L USM is impressively sharp, one of the sharpest zoom lenses we've tested in the 70-200mm range. This is made even more impressive by the fact that the lens design is approaching fifteen years old, designed well before the advent of the digital SLR camera. The lens is exceptionally sharp at 70mm; even wide open at ƒ/2.8, we note results just above 1 blur unit. Stopped down to ƒ/4, it's tack-sharp pretty much all the way to ƒ/11. At ƒ/16 we begin to note some diffraction limiting. But even at ƒ/22, performance is still very good at 2.5 blur units across the frame. Over 70mm, wide open performance at ƒ/2.8 isn't as exceptional - here we note results between 1.5 and 2.5 blur units, which is still quite good. This copy of the lens also shows some slight de-centering at ƒ/2.8 which could account for some specific corners which are softer than others. Still, stopped down to just ƒ/4, the lens becomes nicely sharp between 100-135mm, at just over or right on the 1 blur unit line. Again, it's sharp all the way to ƒ/11 and diffraction limiting becomes more obvious at ƒ/16 and above. If there's a weakness, it's probably at 200mm, where we don't see tack-sharp results as we do at the shorter focal lengths. Wide open performance isn't as good at ƒ/2.8, where de-centering produces a soft upper right corner approaching 4 blur units; overall performance is around 2-3 blur units. Stopping down does improve sharpness, but it isn't until about ƒ/5.6 that the soft corner is reigned in substantially and we see results at the 1-2 blur unit level. At ƒ/8 it's the best it will get, with the majority of the image showing around 1.5 blur units and the right corner showing almost 2 blur units. At ƒ/11 diffraction limiting sets in and performance degrades slightly as the lens is stopped down further. Fully stopped-down performance, at ƒ/32, isn't recommended - images show about 5 blur units across the frame, with focus becoming particularly uneven at the 200mm setting. On the full-frame 5D, the sensor is a bit harder on the lens, showing softer corners that aren't visible through the 20D. The above notes apply to full-frame performance, with a few exceptions: at ƒ/2.8 the lens is very good, showing an average performance of around 1.5 blur units below 200mm. At 200mm a small sweet spot of sharpness is available in the center of the frame, but the sides of the image are quite soft at around 3-4 blur units. Stopping down improves the quality of the image, but you'll need to stop down to ƒ/5.6-ƒ/8 to obtain maximum sharpness, which in this case means just over 1 blur unit below 200mm, and just under 2 blur units at 200mm. If you're keeping score, fully stopped-down performance is actually better on the 5D than the 20D, where at ƒ/32 we note results of around 3-3.5 blur units across the frame. Chromatic Aberration CA tolerance is also very good with this lens, especially in the midrange (100-135mm) where the numbers are extremely low. At wide angle (70mm) and telephoto (200mm) CA results are a bit higher, but happily at these settings CA is kept at it lowest with the lens used at its wider apertures: stopping down increases CA along a fairly linear curve. However, even fully stopped-down, the lens doesn't exceed the level of 6/100ths of a percent of frame height. On the full-frame 5D, CA tolerance is the same, if not slightly better. Shading (''Vignetting'') On the cropped-frame 20D, corner shading isn't really an issue; the only setting which produces any corner shading of note is 200mm, where at ƒ/2.8 we note corners which are 1/3EV darker than the center. At any other setting, light falloff is negligible. Mounted on the full-frame 5D, light falloff is substantially more noticeable. The lens follows a trend along all focal lengths; at ƒ/2.8, the corners are almost a full stop darker than the center; at ƒ/4, we note around a half-stop of light falloff; at ƒ/5.6, the falloff reduces to about a third of a stop. At ƒ/8 the lens reaches the quarter-stop level. Distortion On the 20D, distortion isn't much of a factor: just +0.25% barrel distortion at 70mm in the corners, and -0.2% pincushion distortion at 200mm in the corners. There's a point of 0% distortion at around the 100mm mark. Distortion is predictably a bit more prominent with the lens mounted on the 5D. At 70mm we note +0.5% barrel distortion in the corners, and at 200mm, it's almost -0.5% pincushion. Fortunately the distortion pattern is fairly linear and should be fairly easy to fix in post-processing (if you need your straight lines to be absolutely straight). Again, there's a break-even point at around 100mm which shows very little distortion. Autofocus Operation The EF 70-200 mm ƒ/2.8L uses Canon's ultrasonic motor technology to achieve fast, almost totally silent AF operation. Focusing is quite fast for a lens this large, it taking just over a second to slew from closest focus to infinity or vice versa. That's not amazingly fast, but is pretty nimble for a lens this large, with this much glass to move around while focusing. The focus slew time seemed to be independent of focal length, taking as long whether at 70mm or 200mm. Focus lock was also very fast and sure-footed on our test bodies, and the large ƒ/2.8 maximum aperture will let Canon bodies with special wide-aperture AF provision focus even more accurately. As a lens with the USM specification, you can override autofocus results at any time by just turning the focus ring. Macro With a minimum close-focusing distance of 1.5m (just under 5 feet) and a magnification rating of 0.21x, this isn't really a lens you'll want to use for macro work. Build Quality and Handling Like all the white-body L-series Canon lenses, build quality on the EF 70-200 mm ƒ/2.8L is exceptional. It's built like a tank, and frankly weighs like one as well. This is a heavy lens - almost three pounds heavy - not one that you're going to want to hand-hold all day. The included tripod collar is removeable, and balances very well with typical bodies: It was just slightly front-heavy with our EOS-20D mounted on it. A monopod with a ball head would be a great way to work with this lens. The monopod would relieve your arms of the weight, but the ball head would give you good freedom of movement. The lens isn't weather-sealed like its image-stabilized cousin, though it does feature the same eight-bladed aperture. Canon had moved beyond aperture rings by this point, but there is a recessed distance scale, protected by a clear window. Distances are indicated in feel and meters. There is no depth-of-field scale. Two switches are available on the side of the lens: one to enable and disable autofocus, and a focus limiting switch, with selections for 1.5m - infinity, or 3m - infinity. This is an internal zoom/internal focus lens design, so the body of the lens doesn't extend during either zooming or focusing, nor does the front element rotate. That means this lens will work well with front-element filters that are rotation-sensitive, like polarizers and graduated neutral density filters. The zoom ring is the larger of the two, at 1 3/8'' wide, composed of a dense black plastic and textured with rececssed ridges. The zoom ring turns quite smoothly, although it has a bit more resistance than those on some lenses. A quarter turn runs the lens through its range of focal lengths. The focusing ring is just under an inch wide, composed of the same dense black plastic, but with shorter recessed ridges. The lens ends in hard stops at either end of the focusing spectrum, and manual focusing is fairly smooth with this ring. The lens will focus slightly past infinity. The 70-200 mm ƒ/2.8L comes standard with a large pental-shaped hood that does a good job of shading the front element from flare-producing light sources. That said though, the lens does appear to be fairly prone to flare if you have a strong light source hitting the front element. You'll definitely want to keep the hood in place if you're shooting in direct sunlight or other situations where strong light sources could cause flare. When not in use, the hood can be reversed and stored on the lens for storage. Alternatives Canon EF 70-200mm ƒ/2.8L IS USM ~$1,900 Both lenses are similarly sharp, though in our test copies the non-IS lens was much sharper at 70mm and ƒ/2.8; at 200mm and ƒ/2.8, the edge went to the IS version. Stopped down to ƒ/4 or smaller, it's hard to tell them apart. Performance for CA, distortion and corner shading are similar between the two lenses. Apart from a little more weight, length and image stabilization, the two lenses are practically identical - if you don't mind the extra cost. Canon EF 70-200mm ƒ/4L USM ~$640 Canon makes the 70-200mm ƒ/4 lens in image-stabilized and non-IS versions. Both are significantly lighter and smaller than the 70-200mm ƒ/2.8. The lenses are very similar to their ƒ/2.8 counterparts: stop down the ƒ/2.8 lenses to ƒ/4, and you've got extremely similar performance across sharpness, CA, distortion and corner shading. Essentially, if you don't need ƒ/2.8, there's a big financial savings available for you. Sigma 70-200mm ƒ/2.8 EX DG HSM APO ~$750 The Sigma performs very well when stopped down to ƒ/4, matching the performance of the Canon. But at ƒ/2.8, there is a definite edge to the Canon. Please note that Sigma has produced a new version of this lens, so these results may not stand to current scrutiny. Results for CA, distortion and corner shading are similar. HSM focusing, similar to Canon's USM performance, provides fast and quiet autofocus. Tamron 70-200mm ƒ/2.8 Di LD IF Macro SP AF ~$750 The Tamron performs extremely well, slightly sharper than the Canon at ƒ/2.8 above 70mm. Stopped down, it's a match, perhaps a nod to the Canon. CA is slightly higher, but distortion and corner shading are similar. Tamron's autofocus isn't quite as fast nor as quiet as Canon's. Conclusion The Canon 70-200mm ƒ/2.8L USM performed very well in our tests, perhaps not as sharp as we'd like at 200mm and ƒ/2.8, but quite impressive at 70mm. CA tolerance is very good, distortion is low, and corner shading is very low. Build quality is very high, and autofocus performance is excellent. For the money, you can't go wrong with this lens.