Through a combination of luck and good fortune, Kaz and I have three different Canon cameras - a venerable 20D DSLR, an ultra compact IXUS 70 and most recently the G9. Phil wants to know how much he sacrifices when he takes the G9 cross country skiing instead of the 20D and Kaz wants to prove that the G9 she chose to keep (after Phil won it) is really better than the IXUS 70.
The results really speak for themselves. Keen photographers will find the deficiencies you would expect from each camera. Happy snappers will probably not see much difference at all and wonder why anybody would carry round an SLR when you can put an IXUS in your pocket.
This was a very quick and dirty test, so the shots had to be resized a little as the zoom settings were never exactly the same and to match the 12 megapixels (4000 pixels wide) of the G9. All shots taken using autofocus, autoexposure and shutter priority on a small tripod. The standard 18-55mm kit lens was used on the 20D which I actually find performs pretty well for what it is based on previous tests against other lenses.
Click the small images for the full size comparison (100%).
Wide Angle Test
Lowest possible ISO 100 for the 20D, ISO 80 for the G9 and IXUS70.
The main sacrifrice with the IXUS70 is in contrasty areas, where the purple fringing is excessive in contrasty areas, and washes out leaves against the sky. The G9 suffers just a little by comparison but it is still noticeable by comparison with the clean images from the 20D. Being several years older, the 8 megapixel 20D is actually losing a little in resolution to the 12 megapixel G9.
Wide Angle Test (Click for full size)
The 18-55mm kit lens didn't zoom anywhere near as much as the compact cameras, so it has been upsampled here quite a bit which makes this test pretty harsh on the 20D. Clearly with a nice telephoto lens it would well outperform the compact zooms (On the flip side, at 18mm it gives a much wider field of view than either of the compacts can). The quality of the G9 image here is pretty impressive, while the IXUS70 clearly loses out at the telephoto end. The G9 image is not even the end of its range - the final zoom step produced a significant amount more detail and an even more impressive telephoto performance. Definitely worth carrying around.
Telephoto Test (Click for full size)
ISO 800 Test
This final test shows the sacrifices that are made to cram many megapixels onto small chips. The high ISO performance of the G9 is pretty disappointing. I would have preferred Canon to have traded off a lower pixel count in favour of better high ISO performance. The 20D at ISO 800 looks very clean by comparison. High ISO noise in the ultra compact IXUS70 is not such a surprise.
ISO 800 Test (Click for full size)
Based on a very subjective feel from some early happy snaps, I was worried that the G9 was not really delivering much more than the IXUS70 but this test has proven that it really can deliver pretty impressive results from an all-in-one camera, as long as you don't need high ISO in low light.
In short, the trade-offs and comparisons are exactly what you should expect. A tiny camera necessarily means a lot of sacrifices when the shooting conditions are more contrasty, which is a lot of the time. But the IXUS70 is amazing for what it delivers in such a tiny package. Take this example, a one hand macro tiny widlflower shot:
The lens on the G9 is large enough to actually make something of its 12 megapixels, delivering quality results for a wider range of situations. The downside is the tiny pixels mean a sacrifice in high ISO performance. Image Stabilisation (in both the G9 and the IXUS70) does help a great deal in avoiding the need for high ISO as long as it's you that's moving and not your subject.
The 20D is beginning to show its age but its low noise performance still ranks very highly. The newer SLR models deliver all the resolution advantages shown here by the G9 but with all the power and capabilities of a DSLR.
For more robust and in depth reviews, you have to start with www.dpreview.com.