An excellent mid-range telephoto zoom lens from Canon (Canon EF-S 55-250mm F/4-5.6 IS Lens)

Member Name: markos9

Product:	Canon EF-S 55-250mm F/4-5.6 IS Lens
Date:	19/07/09 (316 review reads)
Rating:

Advantages: High performance and resolution.

Disadvantages: Auto focus can be poor in low light.

Introduction

The Canon EF-S 55-250mm f/4-5.6 IS, to give it its full title, is a relatively new lens designed for Canon's APS-C cameras (e.g. 450D, 500D), so cannot be used on its 'full frame' range (e.g. 5D, 1D).

The lens sits at the budget end of Canon's product range and is available for around £220. It is, however, often sold with the Canon 450D and 40D cameras as a two lens package with the 18-55mm kit lens, giving a superbly capable camera and lens combination.

Canon's APS-C cameras have a 1.6 times 'crop factor' (because of the camera's sensor, smaller than the 35mm film camera, the focal length of a lens attached to it appears to be 1.6 times larger). This means that this lens has a very useful 'effective' focal length range of 88 - 400mm.

The 'IS' designation indicates that this lens has built in image stabilisation. This very useful feature moves the lens internals to compensate for 'camera shake', reducing the chance of a photo being blurred, even with longish exposure times.

Construction and ergonomics

Build quality, for a 'budget' lens, is excellent. The plastic materials of construction do not give a cheap look, but do make the lens relatively light. The tolerances for the moving parts are quite tight and the focal length and focus movements quite smooth, with a nicely knurled grip to aid moving: all in all, this lens looks and feels of a higher quality than its price suggests.

This is a medium sized lens (110mm long when on the camera) which balances on the 450D perfectly. The focus ring sits perfectly placed in my left hand, ready for use, and the IS and auto focus buttons sit just under my thumb.

Lens performance

The image stabilisation works well, photos can be taken (at 55mm focal length) at exposures up to 1/15th of a second without evident camera shake. Without IS, an exposure time of 1/55th of a second would be recommended to avoid image blur.

Auto focus is one of the lens' weak points. Focusing is fast and silent, with the lens getting to the right point very quickly, but accuracy is not great if the light is poor. I find that, in low light, my 450D 'hunts' with this lens, often resulting in an out of focus shot being taken. In bright conditions the lens is a much better performer and, if fitted to a 40D, handles low light much better than when on the 450D.

Image quality

Chromatic aberration (coloured fringes that appear along areas of different contrast) is almost entirely absent, unlike many zoom lenses. Occasionally, I've detected very slight purple 'fringing' on dark/white edges, but only when examined at the pixel level. This is extremely impressive for such a low priced lens.

Contrast is also pretty good; images appear bright and vibrant, especially with a bit of 'tweaking' in Photoshop. The images produced with this lens will, however, have lower contrast, and look slightly more 'washed out' than those produced with more expensive lenses.

Lens flare is extremely well controlled; I've not detected any flare in any of the images I've taken with this lens, even in conditions where flare could be a problem.

Resolution too, is excellent. Cameras are being released with ever more densely packed sensors, putting huge demands on lenses to resolve all of the detail that the sensor can detect. This lens does a very good job of capturing detail. For a zoom lens, the resolution is higher than expected and users can expect to take images that capture incredibly fine detail when taken with a 400D or above.

The second weakness of this lens is 'vignetting'. At 'large' apertures (f/5, f/6.3), the corners of the image are often noticeably darker than the centre. This effect disappears completely at smaller apertures and may not bother everyone.

Like many zoom lenses, this lens suffers from 'barrel distortion' at the wide angle end of the range (55mm). The effect causes straight lines to be curved inwards at the end, like a barrel. The distortion is not severe, however, and will be unlikely to be noticed on most images.

Verdict

This lens is then, light, good to hold, fast, and produces sharp, high resolution images with good contrast. If purchased with the 18-55mm 'kit' lens, the Canon APS-C camera user will have an image stabilised, effective focal length range of 28-400mm which may be all most users ever need. The lens is therefore, an excellent performer for its price. Canon should be congratulated for releasing such a high performing lens for such a bargain price.

Summary: An excellent 'budget' lens.

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