Sigma 150-500mm f/5.6-6.3 DG HSM OS

The Sigma 150-500mm f/5-6.3 DG OS HSM is the company's latest offering in the extreme telephoto zoom budget marketplace and it kicks in with a few eyebrow raising surprises! Replacing the 170-500mm model that is now quite long in the tooth the new lens has a good specification for its price.

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Specification

• Focal length: 150-500mm
• Construction: 21/15 elements/groups
• Max aperture: f/5-6.3
• Min aperture: f/22
• Angle of view: 16.4 - 5° (full frame)
• Min focus dist: 2.2m
• Filter diameter: 86mm
• Dimensions: 94.7x252mm
• Weight: 1.91kg

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Build and handling
The build and handling of this lens is a considerable leap up from its predecessor and bears a strong resemblance in its construction to the well liked 50-500mm EX model. The conventional twin control rings have the focusing at the rear while the front ring controls the zoom feature, extending the barrel as it does so by some 64mm. The lens features a zoom lock to stop this extension when not in use.

The HSM and OS features have made the lens somewhat heavier than the old 170-500mm, although it still comes in at a manageable weight of just under 2kg. And, with the supplied hood reversed on the barrel, the lens will still fit inside the majority of camera bags, this for a 500mm optic is still compact. The front optic though, at 86mm, is a large one, making filters an expensive extra.

Control switches are all on the left side of the barrel and consist of an AF/Manual switch for the focusing and an OFF/1/2 switch for the OS system. With the HSM motor powering the autofocus it is possible to manually over-ride the autofocus without switching the AF off.

The OS, or Optical Stabilisation, is Sigma's version of in-lens stabilisation and works well although it does operate with a slight whine and a minor clunk as it engages or disengages. It is only noticeable in quiet conditions though, and is certainly not intrusive. The No. 1 position controls movements in both horizontal as well as vertical planes while the No 2 setting compensates for movement just in the vertical plane, allowing for panning movement of the camera without interference. At the full extension of the focal range I found it possible to take sharp images down to around 1/100sec quite successfully. Good long lens technique is still a requirement though when using optics with this much pulling power.

To aid this, the lens is fitted with a fairly substantial tripod collar that can double as a carry handle, although it should be remembered that the OS system should be turned off when a tripod is employed.

Focusing is the biggest single improvement over the lens' predecessor, with this one being very quick in comparison. Tracking moving subjects is a breeze with this model and it is even capable of catching up with them, something the older version seldom managed successfully. There is no sign of hunting until you get down to very low light conditions, something that bodes well for the contrast that the lens is capable of producing.

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Optical Performance
Keeping the zoom range down to 3.3x, Sigma have avoided the complicated compromises that go into, for example, their 50-500mm lens, and this has proved valuable in the image quality department. Contrast, although not stunning, is certainly good and, as has been mentioned, is certainly helpful to modern focusing systems. No noticeable distortions are recorded, not that telephoto lenses normally have a problem with this aspect.

Chromatic aberrations, the dreaded purple fringing that can mar high contrast areas of an image, never reared their ugly head throughout the test, despite some very high contrast situations, although on a full frame camera there is slight evidence of some blue/red fringing at the very edges at the longer end of the zoom. This is minor however and no incidences of flare were recorded, although the respectably deep hood was used throughout the period. These results were consistent right across the full width of the frame. The lens also focused down to a respectable 2.2m and still managed to produce high quality images.

150mm at 1/100sec f/8	500mm at 1/100sec f/8
500mm and f/8 at 1/1000sec hand held with the OS system active in Mode 1 rendered this young injured seal nicely.	At 220mm and 1/250sec, using fill flash to illuminate below the peaked cap, this image was again hand held using the OS system and shows fine detail right to the edge in Emma's hair.

150mm at 1/160sec f/5	500mm at 1/100mm f/6.3
This image, from a series capturing the seal's rescue, was shot at 1/640sec and f/8, this time at the 150mm end of the zoom with the OS operating.

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Verdict
In terms of features versus value for money, this lens has to be the telephoto bargain of the century to date. With both a sonic focusing system and an optical stabilisation system, the two of which work well, coupled with a good optical performance and reasonably compact dimensions, I can see this optic finding a lot of suitors. If you want the pulling power of a 500mm in a manageable package, this one should be at the head of your compare list!

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Plus points
Fast focusing
Good stabilisation system
Excellent value for money
Relatively compact

Sigma 150-500mm f/5.6-6.3 DG HSM OS: Minus points
OS system slightly noisy
Tripod foot could be half inch longer to make more comfortable handle.

HANDLING

PERFORMANCE

OVERALL

Test carried out by Ian Andrews www.thewildlifestudio.com