Sigma 50-200mm f/4-5.6 DC OS HSM

Sigma 50-200mm f/4-5.6 DC OS HSM main image
Gary Wolstenholme gives the Sigma 50-200mm a look over with his expert eye.

Sigma 50-200mm f/4-5.6 DC OS HSM: Handling and features
After purchasing a DSLR, many people will add a telephoto zoom to their kit bag at some point in time. Priced at £200 with optical stabilisation included, which promises to tame camera shake, this lens is bound to be a popular choice for those looking to extend their zoom range beyond the standard 18-55mm kit lens. This lens is very compact for its focal length and will suit those wishing to travel light perfectly.

Plastic is used for most of the construction, which is not uncommon for lenses at this price point. The plastics used feel high in quality and the fit and finish of the lens is good. The lens mount is made of metal, which is less likely to wear with frequent lens changes, and the lens barrel is finished in a powder coating. The powder coating looks good new out of the box and adds to the impression of quality, but in my experience it is prone to marking easily over time during normal use. The focusing ring rotates during focusing, and I found it catching my fingers during use. It would've been nice if there was a way of disengaging this when using AF.

Zooming in extends the lens barrel by just over an inch and focusing is performed internally, which means the front element does not rotate. This makes the lens perfect for use with a polariser or graduated filters. The zoom ring is nice and smooth to operate, offering just the right amount of resistance without being difficult to turn.

Nikon users have an alternative in the Nikon AF-S 55-200mm VR, which costs around £30 more and has similar build quality and features. Canon's 55-250mm IS costs around £10 more, but adds another 50mm to the long end of the lens. Sony and Pentax users already have the luxury of image stabilisation built into the camera body (on recent models) so may find cheaper alternatives serve their purpose just as well unless they really want to see the effect of the stabilisation in the viewfinder.

Sigma 50-200mm f/4-5.6 DC OS HSM: Performance
For this review, the lens was tested on a 10Mp Nikon D80 using Imatest.

At 50mm, the 50-200mm gives good resolution across the frame between apertures of f/4 and f/11. With telephotos like this they will rarely be stopped down below f/11 by an average user, so the drop off in resolution at smaller apertures isn't much of an issue.

As the lens is zoomed in, the resolution drops off. By 100mm, the lens produces more than acceptable images for most people's needs, although the edges of the frame are starting to become a little softer at wider apertures. By 200mm the resolution of the lens has dropped further, producing acceptable images for moderate print sizes. At 200mm, the sweet spot for image qualiality is f/16.

Resolution at 50mm
Sigma 50-200mm f/4-5.6 DC OS HSM resolution at 50mm
Resolution at 100mm
Sigma 50-200mm f/4-5.6 DC OS HSM resolution at 100mm
Resolution at 200mm
Sigma 50-200mm f/4-5.6 DC OS HSM resolution at 200mm

Chromatic aberrations are reasonably well controlled at shorter focal lengths, registering just over 0.5pixel widths in Imatest. This will barely cause an issue in most image taking scenarios. At 200mm the CA increases, although not to unacceptable levels, registering 0.8 pixel widths at f/5.6.

Chromatic aberration at 50mm
Sigma 50-200mm f/4-5.6 OS HSM Chromatic aberration at 50mm
Chromatic aberration at 100mm
Sigma 50-200mm f/4-5.6 OS HSM Chromatic aberration at 100mm
Chromatic aberration at 200mm
Sigma 50-200mm f/4-5.6 OS HSM Chromatic aberration at 200mm

The evenness of image illumination produced by this lens is acceptable, with the corners of the images being 1.71stops darker than the image centre at f/4 and 50mm. The illumination becomes pretty much uniform by f/5.6. At 200mm the difference between the image centre and the corners drops to 1.43stops.

The distortion characteristics of this lens are very good, with a barely noticeable 0.645% barrel recoded at 50mm and a wholly acceptable 1.7% pincushion at 200mm. Straight lines will not pose many problems with this lens.

Sigma 50-200mm f/4-5.6 OS HSM bright ring Sigma 50-200mm f/4-5.6 OS HSM painted letters

Strong point sources of light in the frame causes masses of flare and internal reflections with this lens at any point in the zoom range. Typically this takes the form of a multicoloured starburst surrounding the source of light and can be very disturbing. Light sources just outside of the frame cause very few issues, with only slight signs of ghosting and loss of contrast in the image. Using the supplied hood virtually eliminates this, so I'd leave it on all the time.

Sigma's Optical Stabilisation system helps greatly with being able to take images in low light conditions and at slower shutter speeds. I was able to handhold at shutter speeds of 1/8sec at 50mm and 1/13sec at 200mm with the stabilisation enabled and still get sharp shots most of the time. This feature in performs particularly well and should help increase most people's rate of sharp shots when used with the correct technique.

Sigma 50-200mm f/4-5.6 DC OS HSM: Verdict
This isn't an expensive lens, and although it isn't the highest resolution lens I've tested, the results will be acceptable for most people, especially those who rarely produce large prints. The Optical Stabilisation system featured on this lens is very effective indeed when used with the correct technique, allowing sharp shots of static subjects that would otherwise not have been possible without flash, or additional lighting.

Those looking for something to extend their zoom range over the standard bundled 18-55mm kit lens, without having to re-mortgage the house, will probably be pleased enough with the performance of this lens.

Sigma 50-200mm f/4-5.6 DC OS HSM: Pros
Compact Size
Low Distortion
Great Optical Stabilisation system

Sigma 50-200mm f/4-5.6 DC OS HSM: Cons
Resolution not stunning at longer focal lengths
Flare control
Rotating focus ring during AF

FEATURES
HANDLING
PERFORMANCE
VALUE
OVERALL


Sigma 50-200mm f/4-5.6 DC OS HSM: Specification
Price: £200
Contact: www.sigma-imaging.co.uk
Filter size: 55mm
Format: APS-C/DX
Construction: 14 elements in 10 groups
Angle-of-view: 27.9 - 7.1 degrees
35mm equivalent focal length (on APS-C body ): 75-300mm (Nikon, Pentax, Sony), 80-320mm (Canon)
Internal focusing: Yes
Image stabilisation: Yes
Minimum focus: 110cm
Maximum aperture: f/4-5.6
Minimum aperture: f/22-32
Weight: 420g
Size (lxw): 202x74.4mm
In the box: Circular lens hood


The Sigma 50-200mm f/4-5.6 DC OS HSM costs around £199 and is available from Warehouse Express here:

Sigma 50-200mm f/4-5.6 DC OS HSM


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