Canon SD790 IS Optics

Zoom
A fairly standard 3x optical zoom lens, with good performance. Digital zoom performance is about average these days.

The Canon PowerShot SD790 IS features a standard 3x optical zoom, covering a range equivalent to a 35-105mm zoom on a 35mm camera. Results are good at wide angle with strong detail and only a small amount of visible blurring in the corners that doesn't extend very far into the image area. Coma distortion is also slight. At telephoto, results are also good, though blurring in the corners is a little more noticeable. The camera's 4x digital zoom performs about average, with pretty good detail but a lot of artifacts and less definition.

Macro
A small macro area with good detail and high resolution. Closest focusing distance is too close for the flash.

The Canon PowerShot SD790 IS' macro setting performed well, capturing a small minimum area of just 1.31 x 0.99 inches (33 x 25 millimeters). Detail and resolution were both very good at the center of the frame, though there's a moderately high amount of softening in the corners from the lens. (Most cameras have some softening in the corners in macro mode.) The flash had trouble throttling down for the macro area, however, and was also partially blocked by the lens, resulting in a very uneven exposure with a strong hot spot. Plan on using external lighting for any macro shots with the Canon SD790 IS.

Distortion
High barrel distortion, though very low pincushion.

The Canon Powershot SD790 IS's 0.9% barrel distortion at wide angle is higher than average, and quite noticeable in its full wide angle images. At the telephoto end, the SD790 IS's less than 0.1% (about 0.03%) pincushion distortion is really very low -- actually only about one pixel's worth. Distortion 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).

Chromatic Aberration
High and bright at wide angle, though very low at telephoto. Noticeable effect on some images in the corners toward full wide angle.

Chromatic aberration is high at wide angle, showing fairly bright coloration on either side of the target lines. Some blurring in the corners here is likely intensifying the effect, however. At telephoto, the effect is much less visible, with almost transparent color on either side of the target lines. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Sharpness
Moderately high blurring in the corners of the frame at wide angle, less at telephoto.

The Canon Powershot SD790 IS produced fairly soft corners of the frame at full wide angle, which was noticeable in some images. At full telephoto, blurring was almost indistinguishable from the center of the image, a very good result.

Coverage
Very good accuracy from the LCD monitor.

The Canon Powershot SD790 IS' LCD monitor showed about 103% coverage accuracy at wide angle, and about 101% at telephoto. Both are a little loose, but overall results are still good.