August 2008 | Margaret Brown
A competitively-priced, optically-stabilised long-zoom lens for DSLR cameras with 'full-frame' or 'APS-C' sized image sensors.
RRP: $1,299
Rating (out of 10):
- Build: 9.0
- Handling: 8.5
- Image quality: 8.5
- Versatility: 8.8
- OVERALL: 8.8
A close cousin to the APO 150-500mm F5-6.3 DG OS HSM lens, which has also been reviewed on the Photo Review website, Sigma's APO 120-400mm F4.5-5.6 DG OS HSM lens can be used on both 'full frame' and 'APS-C-sized' DLSR cameras as well as traditional 35mm SLRs. Smaller and lighter than the 150-500mm model, it is a significant upgrade on the 135-400mm f/4-5.6 lens it replaces.
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A close cousin to the APO 150-500mm F5-6.3 DG OS HSM lens, which has also been reviewed on the Photo Review website, Sigma's APO 120-400mm F4.5-5.6 DG OS HSM lens can be used on both 'full frame' and 'APS-C-sized' DLSR cameras as well as traditional 35mm SLRs. Smaller and lighter than the 150-500mm model, it is a significant upgrade on the 135-400mm f/4-5.6 lens it replaces.
Key features of the new lens are the inclusion of Sigma's original OS (Optical Stabiliser) and the use of the company's HSM (Hyper Sonic Motor), which provides fast and quiet autofocusing as well as full-time manual focusing capability. Like its sibling, it is compatible with Sigma's APO Tele Converters.
The optical design is similar to the 150-500mm lens, with 21 elements arranged in 15 groups. Three SLD (Special Low Dispersion) glass elements have been included to correct chromatic aberration and super multi-layer coating is applied throughout the optical system to minimise flare and ghosting. For general photography, this lens has a minimum focusing distance of 150cm throughout the zoom range and delivers a maximum magnification of 1:4.2, making it useful for close-up photography.
A rear focusing system minimises the risk of image softening caused by focusing and ensures optimum image quality throughout the entire zoom range. The maximum apertures of f/4.5 at 120mm and f/5.6 at 400m are relatively large for 3.3x zoom lenses of this type.|
Build quality is similar to the 150-500mm lens. With a metal mounting plate and stylish matte black coating. Rubberised focusing and zoom rings ensure a secure and positive grip. As in the 150-500mm lens, 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 measures just under 28mm deep and its rubber coating has thicker ridges than those on the focusing ring, which is 18mm thick. The removable tripod collar fits behind the focusing ring. Just behind it is a distance scale with markings for metres and feet.
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. Full-time Two stabilisation settings are provided, along with an off position.
According to Sigma's website, the lens is supplied with end caps, a hood and a soft carrying case (although we received only the end caps with the review lens).
Handling
Our tests on the sample lens were conducted with Canon EOS 5D, EOS 40D and EOS 400D camera bodies. On the EOS 5D, it was a comfortable match and well-balanced enough to be usable for hand-held shooting. This balance was retained with the 40D body but the lens felt a little too heavy on the 400D.
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 quickly and with minimal hassles. The tripod mounting was also large and stable enough to use when the camera was placed on a level surface for shooting, as shown in the illustration below.
The HSM drive was quiet and autofocusing was fast and accurate under most shooting conditions, although we found a slight tendency to 'hunt' with low-contrast subjects and in dim lighting. However, in bright lighting, the lens locked quickly and accurately onto moving subjects - including birds in flight. Autofocusing was almost silent, thanks to the HSM drive and full-time manual focus override lets you switch from auto to manual focusing without having to move the slider on the lens.
Both the focusing and zoom rings moved smoothly and positively, the latter providing slightly more resistance. The focusing ring was well damped and very smooth to use. Moving from the 120mm to the 400mm focal length requires a roughly one third of a turn and extends the lens barrel by 6.4 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 a little less than half a turn as you go from the closest focus to infinity.
Performance
Although Photo Review wasn'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. There was little point in running tests with the EOS 40D and 400D because we could only test up to 200mm. With the EOS 5D we were able to test it at the 120mm, 150mm, 200mm and 250mm focal lengths.
Overall performance was very good for the review lens's specifications and price tag and resolution was slightly higher than we obtained for the Sigma APO 150-500mm F5-6.3 DG OS HSM lens. Highest resolution was obtained between f/5.6 and f/13 for all the focal lengths we were able to test. Resolution declined steeply from f/18 onwards. Some edge softening was found across all aperture and focal length settings but it was not enough to affect ordinary photography. The results of our tests are shown in the graph below.
Lateral chromatic aberration was generally low, remaining well inside the 'negligible' band for most of our test shots and never rising above 0.027% of distance to corner. We found no evidence of coloured fringing in test shots at a range of different focal length and aperture settings, as shown in the example below.
Vignetting was visible between 200mm and 400mm at apertures down to about f/11 but vanished by f/6.3 at the 120mm focal length. Examples are shown below.
Vignetting at 400mm; 1/400 secodn at f/8.
No vignetting at 120mm; 1/332 second at f/8.
No significant rectilinear distortion was detected. On the basis of our shooting tests in different light levels, we estimate the built-in image stabiliser provided a shutter speed advantage of approximately two f-stops, allowing us to shoot hand-held at 1/90 second with the 400mm focal length. Stabilisation provided a relatively smooth viewfinder image.
Bokeh was not altogether smooth but most potential users would find it acceptable. Overall, this lens would be a good choice for taking action shots of sports and/or wildlife.
IMATEST GRAPHS
SAMPLE IMAGES
EOS 400D; 120mm, 1/500 second at f/8.
EOS 400D; 400mm, 1/400 second at f/7.1.
Backlighting with EOS 400D; 1/250 second at f/6.3.
Sport with EOS 400D; 400mm, 1/800 second at f/10.
Portrait with EOS 40D; 120mm, 1/90 second at f/5.
EOS 40D; 400mm, 1/100 second at f/5.6.
EOS 40D; 120mm, 1/100 second at f/5.6.
Backlighting, EOS 5D; 1/2656 second at f/6.4.
Enlargement from the above shot showing out-of-focus rendering of highlights (bokeh).
Close-up with EOS 5D; 400mm, 1/400 at f/5.
Wildlife with EOS 5D; 400mm, 1/197 second at f/5.6.
Picture angle: 20.4 to 6.2 degrees
Maximum aperture: f/4.5-5.6
Minimum aperture: f/22
Lens construction: 21 elements in 15 groups
Lens mount: Sigma, Canon, Nikon, Pentax*, Sony* (*If the camera body does not support HSM, auto focus will not be available.)
Diaphragm Blades: 9
Minimum focus: 150 cm
Maximum magnification: 1:4.2
Filter size: 77mm
Dimensions (Diameter x L): 92.5 x 203.5 mm
Weight: 1750 grams