Canon’s 70-300mm f4-5.6 IS USM lens is a step up from the average telephoto zoom. Canon also makes a much cheaper 75-300mm, but the lens tested here is designed for photographers looking for a step up in both build and picture quality – and this lens has an image stabiliser.

Like Nikon, Canon has stuck to lens-based stabilisation systems. Pentax, Samsung and Olympus have chosen a different route, building image stabilisation into their camera bodies. With camera-based stabilisation, you get the benefits of anti-shake with any lens. With lens-based systems, you’re paying extra each time you buy a stabilised lens. There are certain advantages to lens-based stabilisation, though. In the future, you’re just as likely to upgrade your camera body as you are your lenses, so think of this 70-300mm IS as a long-term purchase, not just for your current camera, but any you buy in the future, too.

The other advantage is that you get to see the benefits of stabilisation in the viewfinder. At a focal length of 300mm (480mm equivalent), the subject bobs around in the frame like a cork in a storm, but the moment you half-press the shutter, this lens steadies it in the frame, making it much easier to compose long-range shots. You don’t get this with camera-based stabilisation because this only steadies the sensor, not the image in the viewfinder.

Canon claims the IS system in this lens lets you shoot sharp shots at shutter speeds three times slower than usual, and our tests suggest this is a very fair claim. With focal lengths this long, image stabilisation really is a major advantage and, in the gloom of the typical British winter, verging on essential.

On a digital SLR with an APS-C sized sensor, like the Canon EOS 400D or Nikon 40D, the 70-300mm focal range equates to approximately the equivalent of 112-480mm on a 35mm camera. That’s pretty serious telephoto power, and at full stretch this lens can fill the frame with subjects too timid to allow you to get up close, or sports where spectators are kept a long way from the action.

It’s a pretty long and heavy lens, though. It won’t fit in the average SLR holster bag because of its length and you might need to rearrange the compartments in your gadget bag to accommodate it.

It does have an annoying habit, too. The zoom action is very light, which isn’t in itself a problem, but it does mean that if the camera’s pointed downwards, the lens extends. It’s a nuisance both when you’re carrying the camera around (especially on a strap) and when you go to pack it nose-down into a bag.

Canon’s obviously aware of this, providing a switch on the lens's side to lock it at its minimum focal length. Why not simply stiffen up the focusing movement a little instead? But if that’s all we can find to complain about, it must mean this is a pretty good lens – and it is. The resolution tests show excellent definition at 70mm and 135mm, even at maximum aperture.

Performance drops at the maximum focal length, as we’ve come to expect from telephoto zooms. At maximum aperture at 300mm, the results are a good deal softer than at shorter focal lengths, and while the sharpness improves as you stop down, it never reaches the same levels.

Photographers are sometimes disappointed by their long-range telephoto shots and might be tempted to blame their technique or camera shake; in reality, a large part of it will be due to the lens itself. For really sharp wide-aperture telephoto shots at long focal lengths you need professional telephoto lenses – now you know why they cost thousands, not hundreds.

With that in mind, the Canon 70-300mm’s results are very good given its price and

its zoom range. Distortion levels are low and while there is some chromatic aberration creeping in at the longest focal length, it’s nothing like that you see from super-zoom compacts, for example, or cheaper super-telephotos.

Canon also makes a much cheaper 75-300mm zoom, which we’ve mentioned, but if you can afford the extra, this is the one to go for. It’s not just at an advantage in terms of picture quality, but the build and the IS are definite bonuses.

Final Verdict Good performance, decent value and excellent image stabilisation. However, it’s pretty bulky and suffers from ‘zoom creep’ OVERALL

Our lens reviewer, and technical expert, Rod is a veritable photographic encyclopaedia. His illustrious CV has seen him write for many mags, websites and journals.