Canon A540 Optics

Zoom
A generous 4x optical zoom range, with good performance.

The Canon A540 zooms over the equivalent of a 35-140mm range, a bit better than the 3x zoom that predominates in its class. The 4x digital zoom takes it out to 16x total, albeit with the loss of quality that digital zoom produces.

Macro
A small macro area with good detail and high resolution. Flash does not throttle down well at this range, so plan on using external lighting for macro shots.

The Canon A540's macro setting performs well, capturing a fairly small minimum area of 1.64 x 1.23 inches (42 x 31 millimeters). Detail is strong and resolution high, with only a moderate amount of softening in the corners. (Most cameras have some softening in the corners in macro mode.) Note, however, that Macro focuses only at the wide angle end of the zoom range, requiring you to move the lens very close to the subject and consequently blocking much of the available light. The flash, not surprisingly, doesn't throttle down well when shooting that close, so plan on using external lighting for your closest macro shots with the A540. (If you need more working distance for close-up work with the A540, you might consider Canon's model 250D close-up lens ($87), but note that you'll need the LA-DC52G Conversion Lens Adapter as well ($22).)

Distortion
Moderate barrel distortion. (A bit better than average.)

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 A540's 0.71% barrel distortion at wide angle is slightly better than average among the cameras I've tested. At the telephoto end, the A540's 0.09% pincushion distortion is lower than average.

Chromatic aberration
Noticeable at wide angle, all but invisible at telephoto.

Chromatic aberration is evident at wide angle, showing a few pixels of moderately bright coloration on either side of the target lines, but decreases to very low levels at telephoto focal lengths. (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.)

Corner Sharpness
Some softening in the corners of the frame at wide angle, sharp in the center at both wide angle and telephoto.

The Canon A540 produced soft corners at telephoto focal lengths, and very slightly soft ones at wide angle. Corner sharpness at wide angle is better than average, performance at telephoto is about average.

Coverage
Optical viewfinder tight and skewed slightly high, and tilted a little. Very good accuracy from the LCD monitor.

The A540's optical viewfinder was rather tight, showing about 83% of the final frame area at wide angle and 79% at telephoto. However, the LCD monitor showed almost 100 percent frame accuracy at all focal lengths.