Sigma 50-150mm f/2.8 EX DC OS HSM APO

SLRgear Review
December 4, 2012
by Andrew Alexander

The Sigma 50-150mm ƒ/2.8 EX DC OS HSM APO started to hit store shelves in April of 2012, an update to the previous non-optically stabilized version which has seen a few revisions, and has now been discontinued.

The Sigma 50-150mm ƒ/2.8 OS was designed to fit the APS-C sized sensor of digital camera bodies (hence its "DC" designation): using it on a full-frame camera will result in vignetting on the sides of the captured image. It features a maximum aperture of ƒ/2.8 regardless of the focal length chosen. On a Canon body, the 50-150mm lens provides an effective field of view of 80-240mm; on other bodies, the effective field of view is 75-225mm.

The lens is available now in Canon, Nikon, Sigma, Pentax and Sony mounts, ships with a tripod mount and petal-shaped lens hood, and retails from around $1,100.

Image stabilization testing now added!

Sharpness
The Sigma 50-150mm ƒ/2.8 OS is quite simply one of the sharpest zoom lenses we have had the opportunity to test. Even used wide open at ƒ/2.8, the lens provides tack-sharp images, from 50mm to 150mm. Stopping down the lens provides practically insignificant improvements in image sharpness: this lens is just excellent at every setting.

Diffraction limiting sets in at ƒ/11, but there is very little practical impact on image sharpness until ƒ/16, and more significantly when fully stopped down at ƒ/22.

Chromatic Aberration
There's no such thing as a free lunch, and if there is any problem with the Sigma 50-150mm ƒ/2.8 OS, it would be the presence of chromatic aberration. It's not surprising to see; there are 21 pieces of glass between your subject and the sensor, and fortunately, it's not overly present in images. Chromatic aberration shows up in images made with this lens in the form of magenta-green fringing in areas of high contrast, predominantly in the extreme corners of the image. If you would seek to avoid any trace of CA, shoot at 100mm where it is lowest.

Shading (''Vignetting'')
The only point where there is any real shading of the corners is when the lens is being used at ƒ/2.8. In this case we see corners which are 2/3 of a stop darker than the center, when the lens is used at 150mm; at other focal lengths at ƒ/2.8, the corners are around a half-stop darker than the center. At other focal lengths and apertures, corner shading isn't really a problem.

Distortion
Distortion is kept remarkably low for a zoom lens: there is some light barrel distortion when the lens is used between 50-70mm (+0.4%), and very light pincushion distortion when the lens is used between 100-150mm (-0.2%). There is a nice sweet spot of parity at the 80mm mark where distortion is negligible.

Autofocus Operation
Built with Sigma's HSM specification, focus is conducted hypersonically, meaning it is very fast and virtually silent: the lens took less than a second to go from close-focus to infinity. If you're using a compatible body, that is: if your SLR body doesn't support HSM, it won't autofocus at all. Autofocus results can be adjusted at any time by just turning the focus ring, and attached 77mm filters will not rotate.

Macro
The Sigma 50-150mm ƒ/2.8 OS HSM isn't a great macro lens: its close-focusing distance is 80cm (31 1/2 in.) and its magnification ratio is 0.16x.

Build Quality and Handling
The Sigma 50-150mm ƒ/2.8 OS HSM is a solid lens, well-built with a metal lens mount. The lens finish is Sigma's standard matte black with a slightly rubberized texture. The filter ring is a hard plastic, and accepts 77mm filters that won't rotate during focusing or zooming.

The lens sports a few higher-quality features, such as a recessed distance scale covered by a glass plate, internal focusing and a nine-bladed diaphragm. Sigma has done some impressive work under the hood, with 21 lens elements in 15 groups, including 6 SLD lens elements. There are two switches of note: one to enable or disable autofocus, and one to enable or disable optical image stabilization. There are two optical stabilization modes available to be enabled.

The design of the lens might take some getting used to for some: the focus ring comes first, and then the zoom ring closer to the filter end of the lens. The focus ring is quite small, just 7/8'' wide with raised rubber ribs. The ring has about 120 degrees of turning action and ends in soft stops (the focus ring will keep turning, but an increase in resistance lets you know that you have reached the end).

The zoom ring is the larger of the two, quite wide at 1 3/4'' and composed with larger raised rubber ribs. The zoom ring has a throw of around 90 degrees: zoom creep is not a factor with this lens, as it uses internal focusing and thus, the length of the lens does not change with zooming or focusing. The zoom ring is nicely finished, and offers a good level of resistance when turning: it takes around two fingers to turn the ring.

The lens ships with a petal-shaped lens hood with the designation of LH850-02 589. This hood is quite large, adding 4 inches to the overall length of the lens when mounted. The hood does reverse and connect to the bayonet mount of the lens, for easy storage. The interior is ribbed to help cut down on flare. Also shipping with the lens is a removable tripod mount which turns very nicely: however, it doesn't have 90-degree click stops as other manufacturers provide.

Alternatives

Sigma 50-150mm ƒ/2.8 II EX DC HSM APO ~$n/a
Sigma provided the only dedicated competition for this type of zoom lens, and it took itself out of the running by discontinuing the predecessor lens. There's been a dramatic improvement in the newer version of the 50-150mm, pretty much across the board: the new lens is much sharper, chromatic aberration has been improved at the telephoto end, and there is much less distortion. Add on optical image stabilization, and there is every reason to upgrade.

Canon EF 70-200mm ƒ/2.8L IS II USM ~$2,100
Canon doesn't provide a 70-200mm experience for its EF-S mount cameras, so to stay brand loyal you'll have to buy the flagship lens and live with an effective field of view of 112-320mm. Performance is on par with the Sigma (which is something to raise eyebrows over) with perhaps better results when it comes to chromatic aberration.

Nikon 70-200mm ƒ/2.8G ED VR II AF-S ~$2,400
Nikon also does not produce something in the 50-150mm range, so again, for the field of view, you'll have to get the flagship. Performance is on par with the Sigma, though significantly better when it comes to chromatic aberration, corner shading and distortion.

Pentax 50-135mm ƒ/2.8 ED AL IF SDM SMC DA* ~$1,500
Of all the mount choices, Pentax is the only one that offers a lens in the same category as the Sigma, but we have not yet tested it.

Sony 70-200mm ƒ/2.8 G ~$2,000
Sony also does not offer something in the 50-150mm range, so you will have to buy its version of the popular 70-200mm range. We were not blown away by images shot at ƒ/2.8 with this lens, especially at the 200mm end, so we see little incentive to spend twice as much as the Sigma.

Conclusion
Sigma has a habit of identifying shortcomings in the lens offerings by other camera manufacturers and exploiting them: in 2006, with the introduction of the first 50-150mm ƒ/2.8 DC, it managed a coup, offering a 70-200mm experience for the APS-C camera. Sigma has certainly managed to improve on the initial and subsequent redesign of that lens, in the current optically-stabilized implementation. It's one of the sharpest telephoto zoom lenses we have ever tested, and should warrant serious consideration by photographers shooting with APS-C sensor-basd cameras. Not only will you have a significant amount of money, but you will make some great photographs, too.

Product Photos

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.