Canon S3 IS Optics

Zoom

A 12x long zoom, with good 4x digital zoom performance (48x total), image stabilized.

The Canon PowerShot S3 IS zooms over the equivalent of a 36-432mm range. Overall performance is quite good, with good detail and sharpness at both wide angle and telephoto, although there is noticeable chromatic aberration at both ends of the zoom range. The 4x Precision Digital zoom takes it out to 48x total (where spotting scopes live), with better results than we usually associate with Digital Zoom, although still not nearly as sharp as optical zoom.

Macro

Normal Macro captures a large area but Super Macro captures a much smaller one.

The Canon PowerShot S3 IS's Super Macro setting captures a very tiny minimum area of only 1.04 x 0.78 inches (26 x 20 millimeters). While the macro area is quite small, details are somewhat soft throughout the frame, with sharp definition only in the very center of the frame. Also, the lens is so close to the subject in Super Macro mode that it can be a challenge getting enough light to shine in around the edges to adequately illuminate the subject. Most cameras have some softening in the corners in macro mode (evidence of the optical characteristic "curvature of field"), but the S3 IS's blurring extends quite far into the frame. Sometimes, severe curvature of field of this sort is evidence of the camera being asked to focus closer than its minimum focusing distance, but a series of shots with the S3 IS at progressively greater focal distances showed similar behavior.

The S3 IS's flash had trouble throttling down for the macro area and was partially blocked by the protruding 12x zoom lens as well, resulting in a very uneven exposure. (Plan on using external lighting for any macro shots with the S3 IS.)

Distortion

Slightly lower than average barrel distortion, no pincushion at all.

This is the tendency for the lens to bend straight lines outward (like a barrel--usually at wide angle) or inward (like a pincushion--usually at telephoto). The Canon S3 IS's 0.74% barrel distortion at wide angle is slightly less than average among the cameras we've tested, and not terribly obvious in most images. At the telephoto end, the S3 IS shows no measurable distortion at all.

Chromatic Aberration

Fairly pronounced at both wide angle and telephoto.

Chromatic aberration was fairly pronounced at both wide angle and telephoto, showing about 5-6 pixels of bright coloration on either side of the target lines. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.) It's unfortunate to see so much CA in what's otherwise a really excellent lens: We'd give the Canon PowerShot S3 IS stellar marks for optical quality if it only had lower CA; as it is, it's pretty average among the long-zoom lenses we've seen.

Corner Sharpness

Very slight softening in the corners of the frame at both wide angle and telephoto. (Better than most cameras we test, let alone long-zoom models.)

The S3 IS produced slightly soft corners in a few shots, mostly confined to the lower left corner at wide angle. Overall, the Canon PowerShot S3 IS's corner sharpness was better than that of most cameras we test.

Coverage

Very accurate EVF (electronic viewfinder) and LCD monitor.

Both the Canon PowerShot S3 IS's electronic viewfinder and LCD were quite accurate, showing almost exactly 100% of the final frame at both wide angle and at telephoto zoom settings.