Canon SX20 IS Optics

Zoom
An impressive 20x optical zoom lens with good overall performance. Average results from the 4x digital zoom.

The Canon SX20 IS's optical zoom offers an impressive 20x optical zoom range, equivalent to a 28-560mm zoom on a 35mm camera. Performance at full wide-angle is pretty good for such a long zoom, with only minor blurring and coma distortion in the corners. The lens does still fall prey to long-zoom trade-offs, though, with moderate to strong chromatic aberration along the edges of the frame, as well as a some noticeable flare. At full telephoto, sharpness is very good but there is still a fair bit of chromatic aberration at maximum zoom. The camera's 4x digital zoom performs about average, with the typical loss in fine detail and artifacts associated with digital enlargement.

Macro
Smaller than average macro area, with strong detail in the center of the frame. The Canon SX20 IS's flash is not effective this close.

The Canon PowerShot SX20's macro setting captured a fairly small minimum area measuring 1.50 x 1.12 inches (38 x 29 millimeters), using standard macro mode. Resolution and detail are excellent near the center, but corner softness extends fairly deep into the frame, as does chromatic aberration. (Most cameras have some softening in the corners in macro mode.) Exposure is quite uneven, with a strong hot spot along the left side. The PowerShot SX20's flash is almost totally blocked by the lens at this close range, leading to an underexposed image with the flash, so you'll definitely need external lighting for your closest macro shots. Oddly, we were not able to focus any closer in Super Macro than in normal Macro mode.

Geometric Distortion
Higher than average barrel distortion at wide-angle, but virtually no pincushion at telephoto.

The Canon SX20 IS's 0.9% barrel distortion at wide-angle is slightly higher than average compared to the most consumer digital cameras, though not surprising for a 20x wide-angle zoom. Toward the telephoto end, the SX1 IS's less than 0.1% (about 0.03%) pincushion distortion is extremely low; essentially imperceptible. 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).

(Note that the full 20x zoom is too long for this shot in our lab, so we shot at approximately 17x which is about 473mm eq. for our telephoto results here.)

Chromatic Aberration and Corner Softness
High C.A. at both wide-angle and telephoto. Moderate blurring in some corners of the frame at wide-angle, but only slight blurring at telephoto.

Chromatic Aberration. The Canon SX20's 20x zoom lens exhibits fairly high and bright chromatic aberration at both wide-angle and telephoto. The effect extends fairly deep into the frame, but the width and intensity of the fringes reduce as you move toward the center. This is very common among extreme zoom lenses, and can be reduced after capture with aftermarket image editing software. Chromatic aberration is a type of distortion visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.

Corner Softness. The Canon PowerShot SX20's lens produced moderate corner softness at full wide-angle in the top right corner, however softness didn't extend very far into the frame. Other corners were sharper, with the bottom left being the sharpest. Corners at full telephoto were only slightly soft, with the bottom right being the softest, though there was a loss of contrast across the image compared to wide-angle. Overall results are pretty good, especially considering that these shots were taken at maximum aperture, as sharpness generally improves as the lens is stopped down to smaller apertures.

(Note that the full 20x zoom is too long for this shot in our lab, so we shot at approximately 17x which is about 473mm eq. for our telephoto results here.)

Coverage
Excellent accuracy from both the EVF and LCD monitor.

The Canon SX20 IS's electronic viewfinder and LCD monitor both showed essentially 100% coverage accuracy at wide-angle and at telephoto. Great results!

(Again, note that the full 20x zoom is too long for this shot in our lab, so we shot at approximately 17x which is about 473mm eq. for our telephoto results here.)