Canon A590 IS Optics

Zoom
Very good performance with the PowerShot A590 IS' 4x optical zoom lens. Digital zoom also performs well.

The Canon PowerShot A590 IS' optical zoom covers the equivalent of a 35-140mm range, going a little longer than the average consumer digital camera. Performance at full wide angle is good, with good sharpness throughout most of the frame. Some blurring occurs in the corners, but only a small amount is really noticeable. Coma distortion is low also. Results are again good at full telephoto, with only minimal blurring visible in the corners. As you might expect, detail and resolution disintegrate with the 4x digital zoom, though the camera does manage to hold onto a decent level of fine detail. If kept small, images with the digital zoom are usable.

Macro
A small macro area with great detail and resolution. Flash has trouble up close.

The Canon PowerShot A590 IS' macro setting performed quite well, capturing a small minimum area of 2.05 x 1.53 inches (52 x 39 millimeters). Detail and resolution were both very good, though there's a moderate amount of softening in the corners from the lens. (Most cameras have some softening in the corners in macro mode.) The A590 IS' flash had trouble throttling down for the macro area, and was partially blocked by the lens, producing a dark shadow across the lower right and a badly blown out area in the upper left. Plan on using external lighting for any macro shots with the A590 IS.

Distortion
Moderately high barrel distortion, though virtually no pincushion.

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 PowerShot A590 IS' 0.7% barrel distortion at wide angle is slightly less than average, though think this level is still higher than I'd like. At the telephoto end, the A590 IS' less than 0.1% pincushion distortion is very low (really only about one pixel).

Chromatic aberration
Moderately high and bright at full wide angle, and higher but less vibrant at full telephoto.

Chromatic aberration is moderately high at wide angle, showing about 10 or so pixels of bright coloration on either side of the target lines. At telephoto, the effect is spread across more pixels (about 20+), but there's very little coloration. (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
Strongest blurring in the left corners of the frame at both zoom settings, though still favorable results overall.

The Canon PowerShot A590 IS's images were soft in the corners of the frame at full wide angle and telephoto zoom positions, and at both settings, blurring was strongest in the left corners. Blurring was stronger and more noticeable at full wide angle, though the effect didn't extend very far into the frame at all. At full telephoto, the amount of blurring was a little less severe, and once again didn't extend far into the frame. Overall, pretty good results, as the blurring isn't significant in the A590 IS's images.

Coverage
A rather tight optical viewfinder, but good accuracy with the LCD monitor.

The Canon PowerShot A590 IS's optical viewfinder was quite tight, showing about 80% frame accuracy at wide angle, and about 79% at full telephoto. The LCD monitor produced much better results, showing about 103% frame accuracy at wide angle, and about 100% at telephoto. Though a little loose at wide angle, results with the LCD monitor are quite good.