Canon PowerShot SD970 IS

Resolution (12.57)

In addition to image sharpness, our resolution test includes measurements of distortion and chromatic aberration, the color fringing sometimes seen along the edges of objects in digital photos. The Canon SD970 IS proved a strong performer overall, with very good sharpness results but some noteworthy problems in the other two categories.

Stacked against the comparison cameras, the Canon is competitive when it comes to resolution, with its solid image sharpness results brought down a peg by less than stellar results for chromatic aberration and distortion. More on how we test resolution.

Distortion (7.0)

We test resolution at three focal lengths; the widest angle setting, the maximum telephoto and the midpoint. The Canon produced minimal barrel distortion at the 15mm focal length, but at wide angle there was significant 2.5% barrel distortion, and at maximum telephoto some pincushioning. Overall, it isn’t a poor performance (as seen with the Sony T900), but it’s not impressive either.

Sharpness (18.08)

Sharpness is good at all three focal lengths, with a high reading of 2387 lw/ph, thanks in part to aggressive but not unreasonable digital sharpening in the camera software. The best results were found at the wide angle and midrange settings, with some softening when shooting at maximum telephoto.

Chromatic Aberration (7.16)

Chromatic aberration was no problem at the center of the lens, but there is noticeable color fringing as we move towards the corners at all three focal lengths.

Quality & Size Options (7.53)

The SD970 IS offers half a dozen image size options, including one in 16:9 widescreen format. There are two JPEG compression settings, Fine and Normal. The SD970 IS doesn’t support saving to RAW files.

Image Stabilization (8.13)

The Canon SD970 IS uses optical image stabilization, with a lens element that moves in response to the user’s movement to minimize the effect of shaking hands. The system did produce a notable resolution improvement, though not as dramatic as we found with the Sony T900.

To test image stabilization, we place the camera in a rig which moves under precise computer control to mimic moderate hand shake, and shoot at 1/30 second (which is about the slowest speed most users can hold a camera reasonably steady) with image stabilization turned on and off. The resulting photos are analyzed using Imatest software to determine how much resolution improvement the image stabilization provides. More on how we test image stabilization.

Stabilization Comparisons
Canon SD970 IS	Casio EX-FC100	Fujifilm F200EXR	Sony DSC-T900
Stabilization Off
Stabilization On

The Canon SD970 IS produced a modest but worthwhile resolution gain in our test images. It was certainly a vast improvement over the Casio and Fujifilm, which failed to boost resolution at all, though the Sony system proved far more effective in our testing.