Note: while this article talks about the 7D, the information is valid for any EF-S mount body such as the Rebel line, 60D, etc.

While the notion of best is relative to the expected usage, there is one lens that really stands out from the others for crop sensor camera: the Canon EF-S 17-55mm f/2.8 IS USM.

Canon EF-S 17-55mm f/2.8 IS USM

And here is why…

Most flexible zoom range

If you plan to have a single lens, forget about primes, you need flexibility and that is something only a zoom lens can provide. But zoom come in various range and it is tempting to pick the lens with the biggest range to get the the most flexibility, like the Sigma 50-500mm f/4.5-6.3 APO DG OS HSM SLD.

While this reasoning is good, it is not valid in practice because long zoom range often means low image quality at the range extremities. So you want to pick a lens with the smallest usable zoom range for what you are going to shoot.

What is the most useful zoom range then?

Ask a pro photographers/videographer about their favourite zoom and they will say 24-70 or 70-200. Of the two, 24-70 is the most useful for all purpose video shooting so our ideal lens should be around this range. Unfortunately, the 24-70 range is for full frame cameras, put on a 7D, it turns into a 38-112 which is a bit awkward to work with.

Now enters the 17-55 2.8 IS! Once mounted on a EF-S crop sensor, it has an almost equivalent focal length (EFL) to the 24-70!

Image stabilization

Because there is nothing worst than a bouncing clip à la Blair Witch Project, image stabilization is a must. Unless you plan to use a tripod for every take, you will quickly feel the need for it. While HDSLR rigs or monopods are good a providing some support, the IS really helps to improve the overall quality of the clip by keeping the framing constant.

This is why I now recommend to every video shooter to only use lenses with IS when possible.

This is where you should be happy about using a EF-S lens because you have access to a lens that is not available to 5dMrkII user: a 24-70 EFL lens with IS!

Look at any photography forums and you will see a bunch of posts about people who would do anything for a 24-70L2.8IS, yet Canon has not released such a lens and many wonder if they ever will. But fortunately for you, the 17-55 2.8 IS is the nest best thing and you can use it on your 7D!

Wide Aperture

If you want your clips to have the famous cinematic feel, you need to be able to blur the background. And to achieve this result, you need a lens with a wide aperture. The widest aperture available on a zoom is 2.8 and while it is not as good as all these 1.2 and 1.4 lenses, it is a perfect number for video since you dont want the depth of field to be too narrow.

Good image quality

While the lens does not have the L quality tag, you will be hard pressed to find people who complain about its image quality. This lens is that good!

Now lets look at the negative points…

The bad

The biggest complain about the Canon EF-S 17-55mm f/2.8 IS USM is its construction and build quality. While it is not bad, it is a plastic lens and for that price, we expect metal.

The other complain are about the controls rings. While it is a subjective topic, a lot of people find it a bit awkward, the zoom and focus rings are not as smooth as what can be found in L lenses and this is generally were people understand how Canon manages to produce such a great lens for such a (relatively) low price.

Conclusion

Unless you have a very specific need, chances are the Canon EF-S 17-55mm f/2.8 IS USM has the potential of being your favourite lens. It has (almost) everything one can need for video and stills. While a bit expensive, it is unmatched in its category.

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