Sigma 28-70mm f/2.8 EX DG

Originally designed for full frame 35mm film cameras, this lens has now been upgraded as part of Sigma’s programme to make all of their lenses compatible with digital sensors. We take a look at whether this focal range is still useful in the digital age.

Specifications

• Focal length 28-70mm
• Aperture f/2.8
• Angle of view 75.4 - 34.3°
• Filter size / type 67mm
• Construction Elements/groups 14 elements in 12 groups
• Focusing type Internal
• Closest focus 0.33m
• Weight 0.510kg
• Dimensions (Dia x length) 74x87.2mm
• Mounts available Sigma, Canon, Nikon, Pentax, Minolta
• Tripod bush No
• Price £249

Build and handling
As an EX lens, Sigma’s top range, the lens comes with a padded, zip-up pouch and with this re-vamp comes a belt loop that makes the pouch useful. A small point I know, but I do find it relevant. In the box also, is Sigma’s extended warranty documentation, extending the warranty in the UK to a useful three years. A multi-language booklet on the functions of the lens is also supplied. Lens and mount caps, along with a useful petal shaped hood complete the package.

The finish on these EX lenses is a smart matt black that I have found to be hardwearing. Quick lens changes, then forgetting the lens is on the floor of the car, have resulted in them rolling around and popping out from under the seat on route to the next location with no adverse effects!

Zooming from 28mm out to 70mm extends the front element by some 26mm and is achieved by the broad zoom ring that carries a lock at 28mm. The front element does no rotate and the lens remains compact for an f/2.8 constant aperture, and the 67mm filter thread is a reasonable size too.

Due in part to the wide aperture, autofocusing is fast and accurate, although a little noisy by today’s standards. An HSM motor would be a nice addition. Hunting for a lock on was a rare occurrence. The manual focus ring with a basic distance scale takes up the front third of the barrel and the zoom ring is marked at 28, 35, 40, 50 and 70mm.

In use, there is no zoom creep, so the lock mechanism never did get used.

Optical Quality
With lenses that were, or are designed for 35mm film cameras, using them on cropped dSLR cameras has both advantages and disadvantages. The biggest disadvantage is the loss of the wider angles. This, however, is more than made up for by the better edge quality of the view you do get. This lens equates to a 43-108mm (average) on a cropped camera and makes an ideal standard to short telephoto portrait zoom.

With four hybrid aspherical elements and two Special Low Dispersion (SLD) elements in the construction, chromatic aberrations and distortions have been well controlled and I found no concerns on either score. Only slightly soft wide open, as the aperture closed down the lens produced very pleasing results and between f/8 and f/16 was in the area of razor sharp, especially at the wider end!
I have found with a number of lenses made for 35mm film that edge resolution was as good at the edge of a cropped sensor as in the centre and this was again the case and overall I was impressed with this lens.

1/125sec at f/5.6, 45mm	1/250sec at f/8, 28mm
A handy walkabout lens.	Also makes a good portrait lens

Click on each of the comparison photos below to view full size versions

28-70mm set to 28mm at f/8	28-70mm set to 70mm at f/8
28-70mm set to 28mm at f/2.8	28-70mm set to 70mm at f/2.8

Below is our lens test data. To find out how to use this graph look at this article: How we test lenses

Verdict
As a fast and relatively lightweight lens for standard to short telephoto work, this lens has a lot going for it. Although small and light for it’s genre, it is well built, nicely torqued and felt right in use. The picture quality was good throughout and excellent when stopped down. The filter size is not so big that a mortgage is needed for filters and the supplied hood works well. I can see that belt loop ending up on my belt!

In summary the main positive points of the Sigma 28-70mm f/2.8 EX DG are:
Picture quality, especially edges.
Size and weight for f/2.8 lens.
Price (especially from ePz shop)

Negative points are:
Noisy
A little soft wide open
Autofocus

Check the latest price of the Sigma 28-70mm f/2.8 EX DG here

Test by Ian Andrews www.wildaboutkent.co.uk

Add your message