Canon PowerShot SX20 IS Performance, Timings, and Image Quality

PERFORMANCE
If I were limited to carrying only a compact digital camera, I'd pick an ultrazoom every time. You aren't going to drop one in a shirt pocket, but being able to call up a lens focal range from wide angle to serious telephoto out of a single relatively small and light unit is just too much versatility to ignore.

Shooting Performance
The SX20 IS displayed a focus icon about 1.5 seconds after power up, and I could get off a first shot in about 2.5 seconds. Single shot-to-shot times (shoot, write, re-acquire focus and shoot) times were about 2.5 seconds with a SanDisk ExtremeIII 20MB/s card.

Shutter Lag (press-to-capture, pre-focused)

AF Acquisition (press-to-capture, no pre-focus)

Continuous Shooting

* Note: Continuous shooting framerates are based on the camera's fastest full-resolution JPEG continuous shooting mode, using the fastest media type available (300x CF, SDHC, etc.). "Frames" notes the number of captures recorded per burst before the camera stops/slows to clear the buffer.

† Note: The Casio Exilim FH20 has no continuous shooting capabilities at full resolution (9 megapixels). It is, however, capable of shooting at 30 fps at a slightly reduced 8 megapixels. Given this relatively high resolution, we have included the FH20's continuous shooting numbers in our comparison.

AF acquisition times were very good at wide angle and predictably slowed at telephoto, but the SX20 IS press-to-capture time of 0.40 seconds is one of the better results we've seen in a compact digital. Shutter lag leaves nothing to be desired (for a compact) at 0.02 seconds.

Continuous shooting rates at full resolution worked out to 1.1 fps and I quit counting when the SX20 IS reached 20 shots with no sign of slowing. While the camera wants to shoot all day in the continuous mode, there's a blackout of the screen for the first couple of shots in any sequence and once shots begin to display they lag one shot behind - trying to pan on a moving subject can become an exercise in guessing where to point the camera next, especially if you're filling the frame with the subject.

The flash range on the SX20 IS has increased over the SX10 IS (22 ft at wide angle - 12 at telephoto versus 17 ft and 9.2 ft, respectively) and recycle time is "7 seconds or less" versus "12 seconds or less" for the older camera. Canon's figures are based on auto ISO, but shooting in programmed auto at 80 ISO and normally lit conditions, the flash was ready to go again in 4.5 seconds at wide angle and 6.3 seconds at telephoto. I set up a worst case scenario and shot aperture priority at f/8, full telephoto and outside on a moonless night to encourage a full discharge - recycle time was a bit over 11 seconds. While the flash is recharging you'll get a flashing lightning bolt on the screen if you half push to try and focus for another shot (the camera will not allow you to shoot with the flash enabled and recharging), but as soon as the recharge is complete you'll get the focus icon if you're still holding the half push. Here's the flash serving as primary illumination for Simon and as fill for Bandit.

Canon rates battery life (CIPA standard) at 340 shots for alkalines and approximately 600 for NiMH, making the choice of power supply a simple decision.

Lens Performance
Canon's 20x zoom lens has a maximum aperture ranging from f/2.8 at wide angle to f/5.7 at telephoto - the wide end is as fast as the competition but the SX20 IS lags in aperture on the long end, where the other brands max out at f/4.5 or faster. That might be the low point for this lens - with identical ISO sensitivities the SX20 IS wide open can't match the faster shutter speeds the competition can generate at full telephoto. Faster is better for stopping action and helping keep images free from camera shake.

There is some barrel distortion present at wide angle along with some softness in the corners and a bit less on the edges of the frame - telephoto looks to be pretty clear of pincushion distortion and has less softness in the corners and edges. There can be chromic aberration (purple fringing) in some high contrast boundary areas, but enlargements in the 200 to 300% range are typically needed to call attention to this defect - the SX20 IS seems to handle this problem quite well.

The lens can focus from 0 to 3.9 inches in super macro mode, and 3.9 inches to 1.6 feet in Macro Mode (both at wide angle). Perhaps more interesting is the close focus distance at telephoto - 3.3 feet. That much lens that close can give you shots with an almost macro look to them, such as the cactus flowers that follow. I don't know about you, but macro and bees aren't in my vocabulary, so I was more than content to stand off a bit and shoot the flowers at 560mm. The original shots were then cropped to 12x8 inches, producing 287dpi and 248dpi files respectively that will still print nicely.

Original	Cropped
Original	Cropped

The SX20 IS features "optical" image stabilization which has traditionally meant the movement of lens elements as a means to combat camera shake. Canon's press release also mentions the inclusion of "Motion Detection Technology" which on other Canon compacts has meant a function that included the automatic ramping up of ISO sensitivity. There's no mention of MDT in any of the user manuals (the short or long versions), but shooting options that allow you to establish the ISO (P or the manual modes) would ordinarily be the best way to try and avoid having the camera resort to MDT.

Video Quality
The SX20 IS had one of the better quality 720p HD videos I've come across in a compact, and the zoom function of the lens is available. The ability of the camera to switch to video from whatever shooting mode you're in by merely pushing the movie button is a nice feature, and while recording you can always use the shutter button to take a still picture - the camera will take the shot and then continue video capture with the still image capture process incorporated as part of the video.

Image Quality
Default images from the SX20 IS were color accurate and pleasing as to sharpness. Canon's "my colors" palette is available for manual shooting modes and offers 10 color and monochrome shooting options in addition to the default setting of "off." Here are the off, vivid, neutral and positive film color options:

Off	Vivid
Neutral	Positive Film

If you're still not happy with the images out of the camera, the eleventh option of the my colors palette, "custom color," permits adjustment of contrast, sharpness, saturation, red, green, blue and skin tones over a range of 5 settings (default is #3 for each). Here's a shot at the default values and a second with the contrast, saturation and sharpness all set to maximum values.

Default

Maximum sharpness, contrast and saturation

Canon's i-contrast feature may be enabled to expand the apparent dynamic range of the camera by bringing out additional detail in darker portions of images while preserving highlights in the lighter portions. It is also available in the playback menu for post processing of images. Here's a shot with and without i-c.

i-contrast off

i-contrast auto

Auto white balance did a good job outdoors ranging from cloudy to bright, as well as with flash and fluorescent light sources, but shot quite warm with incandescent. There are daylight, cloudy, tungsten (incandescent), fluorescent white and fluorescent H, flash and custom white balance settings available.

Auto White Balance, 3200K incandescent light

I stayed with the default evaluative metering method for all the shots in this review, but there are center-weighted and spot options available. Evaluative could lose some highlights on occasion in high contrast situations, but overall gave me no reason to switch to the other methods.

ISO noise performance is typical for the class and comparable with that of the major competitors - the 80 and 100 ISO crop shots look pretty indistinguishable from one another and 200 is very similar, with a bit of noise creeping in.

ISO 80	ISO 80, 100% crop
ISO 100	ISO 100, 100% crop
ISO 200	ISO 200, 100% crop
ISO 400	ISO 400, 100% crop
ISO 800	ISO 800, 100% crop
ISO 1600	ISO 1600, 100% crop

Noise is becoming more prominent at 400, with 800 and 1600 predictably showing increasing effects. All the shots look pretty good at the small full-frame sizes - again, typical.

Additional Sample Images