Canon EF-S 18-200mm f/3.5-5.6 IS Standard Zoom Lens for Canon DSLR Cameras

I've had the Sigma AF 18-200mm f/3.5-6.3 DC OS lens for several months and found it to give sharper images with my 40D than the Tamron 18-250mm (non-IS/OS) which it replaced. Then along comes Canon with their own superzoom "travel lens" so I bought one to see how it compares to the Sigma. My tests show mixed results regarding image quality. With both lenses wide open the Sigma wins at the wide end from 18-24mm, especially away from the center, while the Canon wins at the 135-200mm long end, also especially away from the center. Further, the Sigma is f6.3 wide open at 200mm while the Canon is f5.6. This is only a small difference, but it does give the Canon even more advantage at 200mm where shutter speed needs to be the highest.

Both lenses auto-focus accurately (no front or back focus) although the Sigma is slower to lock focus in low light and is a little noisier in getting there. Their IS/OS are equally effective at about 3 stops of compensation. Build quality, size and weight are about the same and both use the same 72mm filter size. Sigma includes a lens hood while Canon wants to sell you one.

In summary, the Canon is slightly better for me due to the faster and quieter low-light focus and improved telephoto image quality. The trade-off is poorer image quality than the Sigma for wide angle shots, even after stopping down. Finally, the Canon lens costs about $200 more than the Sigma at this time.

Having used the Canon EF-S 17-85mm f/4-5.6 Image Stabilized USM SLR Lens for EOS Digital SLR's for about two years now, this is the perfect focal length range for use as a day-to-day walkabout lens on my Canon 40D. Other Canon gear that I have include their excellent EF-S 17-55mm f/2.8 IS , their razor-sharp EF 70-200mm f/4L IS , EF 70-300mm f/4-5.6 DO IS , the L-grade-sharpness EF 100mm f/2.8 macro , MP-E 65mm f/2.8 macro , and MR-14EX macro ring lite.

In low light or wider-angle scenery shots, this lens is not as sharp as my 17-55mm f/2.8. When used to photograph macro-like shots of butterflies and flowers, it is not as sharp as my 100mm f/2.8. When used at its 200mm lens to focus onto distant birds and turtles sitting on a stone in a pond, it is not as sharp as my 70-200mm f/4L. But as a one-lens solution for covering that kind of focal lengths, it is pretty good. On sunny days, I use this lens on a 40D with a B&W multi-coated MRC Kaesemann Circular Polarizer. I consider this to be a very useful hiking/travel/walkabout lens. This is my first experience with a Canon lens that does not use USM, and the micro-motor is slightly slower and noisier than USM... but not knowing what to expect, I was expecting even slower focusing and, in most situations, I found its focus speed totally adequate - still very quick and without any back-and-forth hunting in lower lighting. But my main gripe about this lens is that Canon did not use USM (who knows what kind of marketing decisions went into this, much as I wondered why the 40D had a 3.0-inch LCD but kept the same 230,000 pixels as the 2.5-inch LCD on the 30D - one of my main gripes with the 40D). For the price, Canon should have included USM with full-time manual focusing. But I did notice that the price has dropped by more than 60 dollars since I bought the lens less than three weeks ago.

The use of a zoom lock switch to prevent lens creep is a very welcome addition that I always wished that their 17-85mm lens also had. The lens does not rotate during focusing, so circular polarizer filters stay in place.

Unlike Canon's USM lenses, the micro-motor focus design of this lens does not allow you to override the autofocus mechanism until you first flip the AF/MF switch on the lens. Furthermore, while the 17-85mm lens lets you use both the focus ring and zoom ring when the lens hood is inverted on the lens, on the 18-200mm lens, since the focus ring is now placed at the very front of the lens (and in front of the much-wider zoom ring), when its Canon EW78D Lens Hood for EF 28-200mm f/3.5-5.6 Canon SLR Lens (not included with the lens) is inverted, the lens hood's "petals" block most of the zoom ring and I have to use my middle finger and thumb to reach in between the hood petals to rotate the focus ring when the hood is screwed on in its inverted position. I would have much preferred that Canon retain the same focus-ring-closer-to-camera-body design that they used on the 17-85mm. But since I mainly use manual focus on my two 65mm and 100mm macro lenses, this is not that big of a deal for me.

At both 18mm and 200mm wide open, the image corners can be a little on the soft side, but when stopped down between f/5.6 and f/11, the image is sharp from edge to edge. But even Canon's 28-300mm L glass, which is also f/3.5-5.6, has its share of design compromises and sharpness issues in a superzoom lens design. So I think that any lens encompassing this sort of zoom range will be tripping over the physical limitations of what can be achieved when compared with a lens with a smaller zoom range. A 18-200mm lens at a fixed f/2.8 with USM and L-grade glass and weather sealing in a lens that weighs less than 3 pounds would be wonderful, and I would gladly pay a lot more for it as single-lens travel/walkabout lens solution, but that product still only exists in my dreams right now.

This 18-200mm lens will now make my 17-85mm lens the least-used lens that I have, so I may eventually end up selling the 17-85mm lens.