If you feel your camera does not have enough zoom, it is sometimes possible to add a zoom converter. After using for awhile the Canon Pro90IS and its x10 optical zoom, I wanted more zoom (we get spoiled quickly, don't we?) and my choice went on the TCON17. It's made by Olympus but it was known to work well with the Canon. I needed a step up ring to adapt the lens converter to the camera as they didn't have the same diameter. It works well and the only downside is you need to be almost at full zoom to avoid dark corners.
Here are some photos of the camera with the converter installed:
http://www.megapixelworld.com/canonpro90is.jpg
http://www.megapixelworld.com/canonpro90is1.jpg
http://www.megapixelworld.com/canonpro90is2.jpg
A photo of the moon taken with it: http://www.megapixelworld.com/photography/showphoto.php?photo=270

Olly