Camera Accessories

The 50mm f/1.4 EX DG HSM is the first large-aperture 50mm prime lens to be manufactured by Sigma and the company has gone to considerable lengths to include the latest designs and technology. Unlike the 50mm f/1.4 primes from other manufacturers, which use designs that hark back to the 1970s, this lens is bang up-to-date, with a Hyper Sonic Motor (HSM) ensuring silent, high-speed AF; a non-rotating front element and a moulded aspherical optical component.

Significantly larger and heavier than the 50mm f/1.4 lenses offered by Canon, Nikon and Pentax, it is usable on cameras with both 'full-frame 35mm' and 'APS-C-sized' sensors, providing a focal length equivalent to approximately 80mm (in 35mm format) with the latter. The optical design consists of eight elements in six groups with one moulded glass aspherical element for correcting coma and producing superior image quality. Super multi-layer lens coating is included to reduce flare and ghosting.

Most of the additional bulk and weight is due to the huge front element, which has been developed to minimise vignetting at wide lens apertures. It also claims superior peripheral brightness and provides sharp, high contrast images even at the maximum aperture. Build quality is very good with a metal mounting plate that is made from solid stainless steel and comes in versions to suit Sigma, Canon, Nikon, Pentax and Sony DSLR cameras. Owners of Pentax and Sony DSLR cameras should note that, if the camera body does not support HSM, auto focus will not be available.

The rest of the lens barrel appears to be built from high-quality polycarbonate. The front element is recessed roughly a centimeter back from the end of the barrel but moves forwards by approximately 8 mm when the lens is focused at its closest point (0.45 metres). The 77 mm filter ring extends forward of this point and does not rotate, allowing easy use of angle-critical attachments (such as polarisers and graduates).

A 13mm wide ridged, rubberised focusing ring is positioned approximately 15mm from the front of the barrel. It rotates through 90 degrees, moving between 0.45 metres and infinity in about half a turn. Behind it, roughly half way along the lens barrel is a distance scale with indicators in metres and feet. Just behind this scale, depth-of-field indicators are engraved on the lens barrel, with markings for f/8 and f/16 (these relate to the lens on a 35mm-sized sensor).

On the side of the barrel at this point is a slider switch for selecting between auto and manual focusing. Just in front of the lens mount is a marker dot for aligning the lens with the camera. Supplied accessories include front and rear caps, a petal-shaped lens hood (which was not provided with the review lens) and a soft carrying pouch.

Handling
The review lens was supplied with a Canon mount and we tested it on our EOS 5D and EOS 40D camera bodies. On both cameras it was a snug fit - but nonetheless quite easy to mount and remove. Its balance was equally good with both camera bodies but it may be a tad weighty with lighter cameras.

The HSM drive was smooth and quiet and autofocusing was fast and accurate, only slowing slightly at low light levels and with subjects where contrast was very low. Manual focusing was almost as smooth, although we found a slight resistance as the focus approached infinity. You can switch from auto to manual focusing without having to move the slider on the lens, thanks to full-time manual focus override.

Performance
With each of the camera bodies we used for our tests, the review lens turned in an excellent performance, producing sharp images with accurate colours and no evidence of colour bias or coloured fringing. Backlit subjects were handled very well and shots showed little evidence of flare or ghosting.

Imatest showed the lens to be capable of high resolution, although it revealed some edge softening, particularly around the middle of the aperture range. We obtained the highest resolution figures with the EOS 5D at apertures between f/4.5 and f/11 and with the EOS 40D between f/2.8 and f/9. The graphs below show the results of our tests on each camera.

 
Imatest results with the EOS 5D.

Imatest results with the EOS 40D.

Lateral chromatic aberration remained at the 'negligible' level throughout our tests with the EOS 5D but ranged between 0.047% and 0.089% of distance to corner with the 40D, putting it into the 'low' category. The test lens produced a very flat field and no evidence of rectilinear distortion was detected in Photo Review's standard tests. Some vignetting was detected with the EOS 5D - but it was not enough to interfere with overall picture quality. With the EOS 40D, vignetting was not detected.

Bokeh was generally attractive, although at f/1.4 the out-of-focus highlights were occasionally fractured. However they were invariably smooth by f/2.

Conclusion
Although Sigma's 50mm F1.4 EX DG HSM lens is a very good performer and a significantly more modern design than the standard lenses from the main camera manufacturers, it suffers in comparison by being bulkier and heavier - and also more expensive. Key differences are shown in the table below. We weren't able to do comparison tests with other manufacturers' standard 50mm lenses so we can't make any recommendations as to whether their performance is better or not as good.

However, we can say that Sigma's design has dealt effectively with most potential aberrations and the overall performance of this lens is impressive. And its price, though higher, is quite competitive.

IMATEST GRAPHS

With EOS 5D:

With EOS 40D:

SAMPLE IMAGES

EOS 40D, 1/8192 second at f/2.3.

EOS 40D, 1/500 second at f/9.1.

EOS 40D, 1/166 second at f/16.

EOS 5D, 1/1328 second at f/9.9.

EOS 5D, 1/125 second at f/16.

EOS 5D, 1/83 second at f/11.

Backlit subject; EOS 5D, 1/30 second at f/11.

EOS 5D, 1/49 second at f/11.

EOS 5D, 1/21 second at f/11.

EOS 5D, 1/99 second at f/1.4.

EOS 5D, 1/160 second at f/5.

Picture angle: 46 degrees and 8 minutes
Maximum aperture: f/1.4
Minimum aperture: f/16
Lens construction: 8 elements in 6 groups with one moulded glass aspherical element
Lens mount: Sigma, Canon, Nikon, Pentax^*, Sony^* (^*If the camera body does not support HSM, auto focus will not be available.)
Diaphragm Blades: 9 (rounded)
Minimum focus: 45 cm
Filter size:  77mm
Dimensions (Diameter x L): 84.5 x 68.2 mm
Weight: 520 grams