Sigma 50mm f/2.8 EX DG Lens Review

Features and Handling
Performance
Verdict
Specification
Sigma's 50mm f/2.8 EX DG Macro lens offers a basic introduction to macro photography, with none of the bells and whistles such as silent focusing or image stabilisation, at a budget price point of around £255. It offers life size magnification at its closest focus and being a full frame lens it is compatible with both full frame and crop sensor DSLRS.

Canon users have two similar alternatives to choose from. Their EF 50mm f/2.5 Macro lens costs around £225 and is a full frame lens without silent focusing that only offer half life-size magnification at its closest focus. The more recent EF-S 60mm f/2.8 is only compatible with crop sensor Canon DSLRs but offers silent focusing and life size magnification for around £340.

Nikon users also have the option of the Nikon AF-S 60mm f/2.8 G lens, which sports silent internal focusing and life size magnification for around £395.

Sony also currently offer a 50mm f/2.8 macro lens which costs around £470 and also lacks silent focusing. Pentax also offer a similarly specified lens which costs around £410.

In this review we'll investigate whether this budget macro optic can really hold its own.

Sigma 50mm f/2.8 EX DG: Handling and features

Weighing only 320g, this is a lightweight lens that could be easily carried around all day ready for when it's needed and at only 66.5mm long, it is quite compact too. The lens barrel is constructed from high quality plastics finished in a smart looking powder coated finish. During use this finish tends to show rub marks easier than other lens finishes, so care may need to be taken to preserve its looks.

The front filter thread accepts 55mm filters, which are readily available. As the thread does not rotate during focusing, polarising filters are easy to use. At it's closest focus the lens extends by over an inch and the magnification ratio is clearly marked on the lens barrel.

Focusing is a little slow on the Nikon D700 used for testing and the lens tends to hunt around, especially in low light conditions. A focus limiter switch is provided to prevent the lens from tracking through the whole focus range when it can't achieve focus easily.

The manual focus ring isn't damped at all and feels a little gritty in operation compared to some other lenses. Saying that the mechanism has enough resistance stay put, plus the large distance between infinity and the closest distance on the focus ring makes fine adjustments easy to make.

The minimum focus distance is 18.9cm, which provides a working distance of around an inch. This can make getting light onto your subject difficult in some circumstances, and may be too close for those wishing to photograph moving subjects such as insects. As the lens is focused closer the effective aperture of the lens drops, which is normal for a macro lens. Unfortunately the maximum aperture of f/2.8 is only available with the lens set exactly on infinity, with the effective aperture dropping as soon as focus is moved any closer.

Sigma 50mm f/2.8 EX DG: Performance

When shot wide open, this lens produces images with fairly good sharpness in the centre and the quality towards the edges isn't far behind.

As the lens is stopped down, the quality improves and peak quality across the frame is achieved at f/8, where the resolution in the centre is outstanding, and the performance towards the edges is very good.

Resolution at 50mm

How to read our graphs The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on a Nikon D300 using Imatest.

Chromatic aberrations are kept within acceptable levels. They are at their worst when shooting wide open, where they can cover 0.92pixel widths. This level of fringing shouldn't cause any issues, even in large prints, or harsh crops from the edge of the frame.

Chromatic Aberrations at 50mm

How to read our charts Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more. For this review, the lens was tested on a Nikon D300 using Imatest.

Falloff of illumination towards the corners is reasonably well controlled. At maximum aperture the corners of the image are 1.44 stops darker than the image centre. Stopping the lens down to f/5.6 results in visually uniform illumination.

Only 0.465% barrel distortion was picked up by Imatest. This is an extremely low level and shouldn't pose any issues for general use. However if your application requires this to be corrected, you'll be glad to know the distortion pattern is uniform across the frame, making it simple to correct in image editing software afterwards.

This lens dislpayed very few issues with flare or loss of contrast during use. Shooting directly into a strong light source will result in a slight loss of contrast. A circular hood is supplied with the lens, which screws into the filter thread and does a reasonable job of shielding the lens from extraneous light.

Maximum magnification – ISO200, 1/125, f/11, 50mm		Low distortion – ISO200, 1/200, f/8, 50mm
		(Above) ISO280, 1/125, f/7.1, 50mm (Left) ISO500, 1/125, f/5, 50mm

Sigma 50mm f/2.8 EX DG: Verdict

This 50mm macro from Sigma is a very capable lens for the price and should make a good introduction to macro photography, especailly for those on a budget.

The quality it is able to produce when stopped down is excellent, and although it doesn't have many of the bells and whistles of more expensive lenses, such as image stabilisation or silent focusing, with care it can still take great pictures.

Sigma 50mm f/2.8 EX DG: Pros

Good value for money
Excellent sharpness when stopped down
Compact size
Low distortion

Sigma 50mm f/2.8 EX DG: Cons

Could be sharper at maximum aperture
Short working distance can make it difficult to light your subject

FEATURES
HANDLING
PERFORMANCE
VALUE FOR MONEY
OVERALL

Sigma 50mm f/2.8 EX DG: Specification

Price	£254
Contact	http://www.sigma-imaging-uk.com
Filter size	55mm
Format	Full-frame
Construction	10 elements in 9 groups
Angle-of-view	46.8 degrees
35mm equivalent focal length (on APS-C body)	75mm
Internal focusing	No
Image stabilisation	No
Minimum focus	18.9cm
Maximum aperture	f/2.8
Minimum aperture	f/45
Weight	320g
Size (lxw)	71.4 x 66.5mm
In the box	Lens hood