Here are some more sample photos, this time demonstrating the digital zoom quality. I took the SX220 to the north bank of the River Thames, put it on my tripod, and aimed it at the London Eye. I took the pictures with a 10-second delay in Av mode with an aperture of f/8 for maximum stability and detail. I let the camera take care of shutter speed and ISO though, on reflection, I probably should have fixed the ISO at 100.
No post-processing was done to any of the photos. I imported them into Lightroom, which made no adjustments at all other than adding some keywords and a copyright, then I uploaded them using Jeff Friedl's excellent Flickr uploader plugin.
I started out by taking photos at the extremes of the optical range, 28mm and 392mm, then I took a couple using the SX220's "Digital Tele-Extender" mode; this seems to digitally crop and upsample part of the picture so that you get the effect of magnifying the optical zoom by 1.5 times and 2.0 times. Lastly I switched to standard digital zoom and took a picture with maximum optical + digital zoom: an effective focal length of (28 x 56) 1,568mm.
To really get an idea of how good (or not) the SX220 is when zoomed, you'll probably want to click each picture to go to Flickr and look at the photo at its original size.
SX220 Sample: Eye 28mm
1/640 sec @ f/8, ISO 160There is a lot of purple and green chromatic aberration because the picture was taken on a bright, sunny, contrasty day. There is also a lot of barrel distortion at this focal length. And you'll see some of the luminance noise typical of this camera. Of course: it's a compact.
SX220 Sample: Eye 392mmIMAGE LINK: http://www.flickr.com …arryknight/5597851169/in/ 1/500 sec @ f/8, ISO 200The chromatic aberration is still there. There doesn't seem to be a lot of pincushion distortion but it's not easy to tell with a photo like this one. It's still noisy but you could get reasonable prints out of it as long as they're not too large. Viewing it at 1024x768 size shows that the picture is still fairly crisp.
SX220 Sample: Eye 1.5x Tele-ConverterIMAGE LINK: http://www.flickr.com …ight/5597852253/in/stream 1/500 sec @ f/8, ISO 250Viewed at 640x480 you can see that the SX220 has done quite a good job interpolating the picture up to an effective focal length of 588mm. At 1024x768 you can see that it's started to lose a bit of detail. Viewing it at the original size shows how much detail it's lost; it looks like the photo was taken at a high ISO.
SX220 Sample: Eye 2x Tele-ConverterIMAGE LINK: http://www.flickr.com …ight/5597854261/in/stream 1/500 sec @ f/8, ISO 200Viewed at 640x480 there's still a lot of detail present, and at 1024x768 the results seem as good with the 2x digital tele-converter mode as they do with the 1.5x. This is giving us an efl of 392x2 = 784mm. There aren't many DSLR lenses that will give you that.
SX220 Sample: Eye Full Digital ZoomIMAGE LINK: http://www.flickr.com …ight/5598436476/in/stream 1/500 sec @ f/8, ISO 320This last one was taken with the full optical zoom - 392mm - plus full digital zoom - which the camera reports as 56x. This gives us an effective focal length of 1,568mm. On a DSLR you'd need an 800mm lens fitted to a 2x extender. And you'd get much better results than the SX220 can achieve, as you'd expect. Looking at this photo at 640x480 you can see that it's messy. And this was taken with the camera on a tripod. It hardly seems worth anyone's time using standard digital zoom on this camera.
Summing upWhether or not you decide to use digital zoom at all on this camera might depend on whether or not you intend to print your photos. I'm happy to use it while out in the field in order to zoom in even further while viewing a picture, perhaps in cases where I'm not entirely sure what's going on in the far background. In other words, as a kind of spotting scope. And this is probably about the only use for digital zoom, even if you don't print your photos, unless you only intend them to be viewed at one fixed size. If that's the case, and if that fixed size is not too large, I think you'll find the results you get with the tele-converter function crisp and detailed enough. Other than that, I'd say don't bother with it. But hats off to Canon for getting such good results in a compact camera.
