Camera Accessories

Sigma's APO 150-500mm F5-6.3 DG OS HSM lens is a telephoto zoom with a 3.3x magnification ratio that will suit photographers who enjoy taking close-ups of sports or wildlife. Although not particularly fast, it is reasonably portable and has an affordable price tag for its build quality and optical composition.

The optical components consist of 21 elements arranged in 15 groups, with three SLD (Special Low Dispersion) glass elements to correct chromatic aberration and Super multi-layer coating to minimise flare and ghosting. It is fitted with Sigma's Optical Stabiliser, which claims to provide approximately four f-stops of shutter speed advantage. Sigma's HSM (Hyper Sonic Motor) is also provided to ensure quiet and high-speed autofocusing.

Designed for use on both 'full-frame' and 'APS-C' DSLR cameras, it comes with mounts to suit Sigma, Canon, Nikon, Pentax and Sony cameras. A removable tripod socket (TS-31) is included as a standard component. We tested this lens on a Canon EOS 5D body, which provided an excellent balance for the almost 2 kilogram weight of the lens.

Overall build quality is excellent. The 150-500mm lens has a metal mounting plate and stylish matte black coating. Rubberised focusing and zoom rings ensure a secure and positive grip. Unlike many lenses we've reviewed, the zoom ring is towards the front of the lens barrel with the focusing ring about mid-way back to the camera. The zoom ring in broader and its rubber coating has thicker ridges than those on the focusing ring. The tripod collar fits behind the focusing ring. Just behind it is a distance scale with markings for metres and feet. The closest focusing distance is 2.2 metres.

Just behind the zoom ring on the side of the barrel is a lock that prevents the lens from extending when carried on a downward-facing camera. Behind the focusing ring are two sliders, the top one switching between auto and manual focus modes and the lower one controlling the optical stabiliser.

Two stabilisation settings are provided, along with an off position. We assume one of these modes covers vertical stabilisation only (to allow for panning), while the other provides both vertical and horizontal stabilisation.

However, since we received no documentation with the review lens we can't say definitively which is which.

There's nothing on Sigma's website (or local distributor, C.R. Kennedy's) to clarify the issue - or to provide details of any accessories that are supplied with this lens. We only received the front and rear caps. The front of the lens is threaded for 86mm filters. 

Handling
Despite its length and weight, the review lens was relatively easy to mount on the EOS 5D body and surprisingly comfortable to use for hand-held shooting. This balance was retained when the camera and lens were tripod-mounted. It also handled reasonably well on the EOS 40D but was too heavy and out-of-balance on the much lighter EOS 1000D and 400D models.

The tripod mounting was easy to attach to a quick-release plate and provided excellent balance with the heavier cameras. A locking wheel on the left side allows the position of the camera-plus-lens to be adjusted along the vertical axis.

The HSM drive was quiet and autofocusing was generally fast and accurate under most shooting conditions. Both the focusing and zoom rings moved smoothly and positively, the former providing slightly more resistance than the latter.

Moving from the 150mm to the 500mm focal length requires a roughly one third of a turn and extends the lens barrel by 6.5 cm. Setting intermediate focal lengths was easy, thanks to legible markings and adequate spaces between them. In our tests, the marked positions were almost always in line with the focal length settings.

The focusing ring moves through roughly half a turn as you go from the closest focus to infinity. AF noise was relatively low, thanks to the HSM drive. We observed little tendency to 'hunt' with low-contrast subjects, except in dim lighting. Backlit subjects were handled with ease. 

Performance
We weren't able to run Imatest tests throughout the review lens's entire zoom range because we didn't have enough distance leeway in our testing set-up. Nevertheless, we managed to test it at 150mm, 200mm and 250mm focal lengths. Overall performance was very good for the review lens's specifications and price tag. The results of our tests are shown in the graph below.

Lateral chromatic aberration was negligible in our Imatest tests. There was no evidence of coloured fringing in shots taken in bright outdoor lighting. A sample crop is reproduced below.

 
A crop from the image below, magnified to 200% to show the absence of coloured fringing.

The full-frame image. Note the slight vignetting in the corners of the shot.

Slight vignetting was observed at the 150mm and 200mm focal length settings, as you can see in the full-frame image above. But by 250mm this was negligible. No significant rectilinear distortion was detected. Images were not as pin-sharp as the EOS 5D is capable of when we shot with wide lens apertures at the longer focal length settings but they would be considered acceptable by most potential users of this lens. Bokeh was acceptable - but not spectacularly beautiful.

The image stabilisation system allowed us to shoot hand-held at shutter speeds as low as 1/30 second at mid-range focal length settings. We had a couple of instances when autofocusing missed the mark when shooting fast action, particularly when burst mode was used with longer focal length settings. However, no lapses were noted for stationary and slow-moving subjects. 

SAMPLE IMAGES

150mm focal length, 1/500 second at f/9.9.  

500mm focal length, 1/250 second at f/9.1.  

500mm focal length, 1/500 second at f/8. 

500mm focal length, 1/500 second at f/8. 

500mm focal length, 1/500 second at f/9.1.

500mm focal length, 1/640 second at f/10.

500mm focal length, 1/50 second at f/8. 

430mm  focal length, 1/50 second at f/6.3.

340mm focal length, 1/30 second at f/6.4.

Focal length range: 150-500mm
Picture angle: 16.4 - 5 degrees
Maximum aperture: f/5.0-f/6.3
Minimum aperture: f/22
Lens construction: 21 Elements in 15 Groups
Lens mount: Sigma, Canon, Nikon, Pentax, Sony
Diaphragm Blades: 9
Minimum focus: 220 cm
Filter size:  86mm
Dimensions (Diameter x L): 94.7 x 252 mm
Weight: 1.91 kilograms