Comparing Canon Cameras: SD200, XSi/450D and 7D

In my family, we own three Canon camera at this moment, the ancient but incredible SD200 (3.2 MegaPixels, point-&-shoot), the Canon XSi (450D in Europe; 12.1 MP Digital SLR) and my recently-acquired 7d (18.1 MP DSLR).

There are gazillions of side-by-side comparisons of digital cameras on the "Internets", so my contribution is not going to be profound. But it is interesting to me because I feel that our SD200 is WAY better than it should be, and my XSi is worse than it should be.

So here is the first A-B-C comparison. This morning (at 8:30 AM CDT), I took a shady picture of the deck in our back yard with each camera set to automatic, flash off, on a tripod. Here is the un-processed result from, first, the SD200:

(Click on the image to see the full res version.)

Now the XSi.

(For the XSi and the 7D, I used the exact same lens: The Canon EF 50mm f1.8.)

The automatic image from teh 7D is 9.2 MB, and this blog has a limit of 8 MB per image, so I resized it from 5184x3456 to the same size as the XSi image, 4272x2848. Here it is:

For the final stage of this little test, I ran the "I'm feeling lucky" process from Picasa on each image, and then exported them to 1600 pixels. SD200:

The XSi processed image:

And the 7D processed image:

Conclusions for this subject: The SD200 has significant "bluing" around the edges. There is not a lot of difference between the XSi and the 7d, but there may be a small improvement in the sharpness from the 7D: look at the grass blades in front of the step.

More later