As you have probably gathered by now, there are several ways to approach city shots like you want, depending upon the result you want to see in the final image.
A fisheye lens can give you the widest view... up to 180 degrees (watch out, it's easy to get your toes in the shot!). However, fisheye lenses will render many of the straight lines in your shot as strongly curved. You might be able to use "de-fishing" software to reduce this effect, but often end up with some loss of image quality and/or need to crop the de-fished image back to a rectangle and lose some of the wide effect of the lens. Still, check out fisheyes at the links other responses have provided and see if they'll do what you want.
An ultrawide, rectilinear lens is something you already have an excellent example of... your 10-22mm. This type lens can give upwards of 100 degree angle of view, is more "corrected" than the fisheye lens, though it still gives some curvature and perspective effects. It is possible to take multiple shots with a lens of this type (tho perhaps best not at it's widest setting), then stitch the images together. For example, the below composite image was made from three separate (handheld) shots with an ultrawide zoom at about 14 or 15mm, if memory serves....
There is some distortion in the above image... but the angle of view here is close to 180 degrees (the "bushes" in either lower corner are actually the top of a hedge that was running straight across in front of me when I was shooting). The blank area where I put my watermark was deliberate... the client wanted room to put a headline, to use this image as a banner on a web page. The three images were combined using Photohop's Photomerge. The images needed some overlap as well as some extra space at the extremes, because the final composite needed to be cropped to remove uneven edges. Using a single image made with a wider non-fisheye lens and cropped into a panorama wouldn't have been as wide and would have had more distortion effects.Using a less wide lens, possibly taking additional images and carefully moving the camera parallel to the subjects, would have been next to impossible handheld but would have reduced the amount of distortion.
Speaking of which, you might be interested in Gigapan, which is an extreme version of panaromic shots stitched together. It uses a robotic controller atop a tripod, sometimes taking as many as 200 or more shots, then combine them using special software. The result is a massive image (sometimes 1GB or more in size) with incredible detail. Check out some of the cityscapes in the galleries here: http://gigapan.com/galleries/landing_page
Photographer George Lepp (www.georgelepp.com) has done some Gigapan work, too... often scenics. I recall one of the Royal Gorge in Colorado he shot with a 70-200 lens (on a full frame camera). He's also made some macro images with the technology.
Whenever you mention shooting architecture, Tilt Shift lenses are going to come to mind. These are used to correct for a common perspective problem in architectural images.... "Keystoning" occurs when you shoot a building from a low angle (i.e., from the street or sidewalk), and the building appears to be tipping over backwards in the final image. Canon's TS-E lenses, the wide angle 17mm and 24mm in particular, are useful helping to correct for that effect. Some correction also is possible in post-processing software, but the results often aren't as good as when it's corrected at the time it's shot.
The Hotel Del Coronado in S. California isn't in danger of tipping over backwards, but sorta looks that way in the shot below, which I took from the only place I could shoot it that day, using an older 21mm lens (on a film camera, about the same as 13mm focal length with your 10-22mm lens on your camera)....
For the below, I used Photoshop's Perspecive control to mostly correct the vertical lines in the image. It's a little better, but there was some loss of resolution in parts of the image (not visible at Internet resolutions). Also notice how the horizontal lines and shapes of the building remain or start to look more skewed, the bench and sign in the foreground are more distorted (trapezoidally), and how the image needed to be cropped a bit tighter after the perspective correction....
Some day I'll go back and shoot it with the TS-E 24mm or 17mm lens, and it will be much better!
When I'm out shooting a city, I'll use an ultrawide much of the time for handheld stuff. But other times I'll take a TS-E lens and tripod, for a more careful shot. For detail shots I also often take a macro lens, which is a short telephoto. And for street life, activities, I'll use slightly wide to short telephoto prime lenses that offer fairly large aperture for low light shooting and are relatively small and unobtrusive.
This was shot with the 10-22mm....
This with a Tamron SP 60mm f2.0 macro lens...
You've got to be careful using wide angle lenses close to objects and people, due to the lens' inherent perspective and anamorphic distortion effects....
Whle a telephoto can be used to compress an image, as well as blur down foreground and background objects...
In just two lenses, your 10-22mm and 28-135mm, you've got a pretty darned good compact, walk-around kit that would be great shooting in cities. The 28-135mm is quite close focusing, too, for detail shots. Those should handle most situations.
Unless you want to get into something specialized like a fisheye, Gigapan or Tilt-Shift... Eventually you might want to add a low light prime such as an EF 28/1.8 USM (pretty compact, even with it's lens hood) or short tele such as an EF 50/1.4...
Hope this helps!
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
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