Canon's range of EF-S lenses are designed to only fit on its APS-C range of cameras. With an 11X focal length range, the Canon EF-S 18-200mm lens is the manufacturer's most ambitious consumer lens. Complete with image stabilization, it's an impressive offering. But can the lens cope with such a wide focal length range?
Pros
- Great image stabilization system
- Excellent build quality for a lens of this class
- Good central sharpness at all focal lengths
Cons
- Large amounts of barrel distortion at wide angle
- Chromatic aberration at either end of zoom range is pronounced
- Not very useable at 18mm
Build Quality
The Canon 18-200mm lens is surprisingly well built for an EF-S lens. While it's made of plastic, it's at least high-quality plastic, and the lens mount is metal. The Canon 18-200mm lens itself is surprisingly compact, considering its massive focal length range, and it is quite lightweight.
Canon has included a zoom lock button, which is great, as it helps prevent this front heavy lens from sliding towards 200mm of its own accord. The Canon 18-200mm lens also benefits from a large zoom ring and a manual focus ring that, while slim, is easy to locate and operate with just an index finger.
Autofocus
Like most lenses in this class, the Canon 18-200mm lens struggles to focus in low light.
A little disappointingly, the lens uses a micro motor system as opposed to the ultrasonic motors (USM) found on many of Canon's other lenses. The micro motor is slower and noisier, and the focus ring spins during focus, meaning that manual focusing can only be activated by switching the AF/M button.
While its focusing speed and accuracy is by no means shoddy, the micro motor system can't compete with a USM. But the micro motor is one of the things that helps to keep the price down.
Optics
A lens that covers such a vast range of focal lengths is never going to win awards for superb image quality. But the Canon 18-200mm lens produces good central sharpness at all focal lengths. Its best overall sharpness is produced at 50mm and around 200mm. Unfortunately, at 18mm, the sharpness drops quickly from the center, making the lens almost un-useable. It does improve quickly though.
Chromatic aberration is extremely high at both wide-angle and full telephoto, showing strong red/cyan fringing at wide angle, along with very strong blue fringing at 200mm. This is coupled with high levels of barrel distortion at wide angle.
In Conclusion
Considering the enormous range this lens has to cope with, the Canon 18-200mm lens is a surprisingly good lens. Image stabilization is excellent, the lens is well built, it's resistant to flare, and image quality isn't bad ... as long as you stay away from the extremes.
It's just a real shame that the problems at the extreme wide angle make this lens almost un-useable at 18mm. But for those looking for an all-purpose lens for, say, traveling -- while keeping the weight of your camera bag down -- this is a good choice. Just don't expect award-winning image quality!