Timing & Performance
In use the SD550 feels very fast, and very responsive in everyday use, something our tests bore out (note the performance appears to be identical to the SD500). From powering up, to zooming, to using the menus, taking pictures and using the flash, the SD550 performs brilliantly, rarely - if ever - leaving you waiting. Unusually for a Canon the processing speed (thanks to the DIGIC II processor) is almost matched by focus speed, which is very respectable indeed, rarely hunting, and rarely taking more than half a second to find its mark even in low light at the long end of the zoom. This is the fastest focus we've ever seen from a Canon compact camera. Continuous shooting performance is also very good for a 7 megapixel ultra- compact, as long as you use a fast SD card, and the shutter lag, especially when using the optical viewfinder, feels instantaneous. Excellent.
All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 3072 x 2304 SuperFine JPEG image (approx. 2,650 KB per image). The media used for these tests was a 1.0 GB SanDisk Extreme III SD card.
|Power: Off to Record||1.0|
|Power: Off to Play||Image displayed||1.1|
|Power: Record to Off||All activity ceased||1.7|
|Power: Play to Off||When buffer is empty||~0.0|
|Record Review||Image displayed||~0.5|
|Mode: Record to Play||1.6|
|Mode: Play to Record||Lens already extended||~1.3|
|Play: Magnify||To full magnification (~10x)||~0.8|
|Play: Image to Image||Time to display each saved image (no transition)||~0.2|
|Play: Image to Image||Time to display each saved image (with transition effect)||~0.5|
|Play: Thumbnail view||3 x 3 thumbnails||~0.4|
|Zoom from Wide to Tele||37 to 111 mm (3 x)||1.3|
|Half-press Lag (0->S1)||Wide angle||~0.35|
|Half-press Lag (0->S1)||Telephoto||~0.45|
|Half to Full-press Lag (S1->S2)||LCD live view||< 0.1|
|Half to Full-press Lag (S1->S2)||Viewfinder||< 0.1|
|Full-press Lag (0->S2)||LCD live view, wide angle||~0.5|
|Off to Shot Taken||LCD live view||~1.4|
|Shot to Shot||Flash off||1.4|
|Shot to Shot||Flash on (red eye reduction off)||1.8|
|Shot to Shot||Flash on (red eye reduction off)||2.7|
Lag Timing Definitions
|Half-press Lag (0->S1)
Many digital camera users prime the AF and AE systems on their camera by half-pressing the shutter release. This is the amount of time between a half-press of the shutter release and the camera indicating an auto focus & auto exposure lock on the LCD monitor / viewfinder (ready to shoot).
|Half to Full-press Lag (S1->S2)
The amount of time it takes from a full depression of the shutter release button (assuming you have already primed the camera with a half-press) to the image being taken.
(Take shot, AF/AE primed)
|Full-press Lag (0->S2)
The amount of time it takes from a full depression of the shutter release button (without performing a half-press of the shutter release beforehand) to the image being taken. This is more representative of the use of the camera in a spur of the moment 'point and shoot' situation.
(Take shot, AF/AE not primed)
The tables below show the results of our continuous shooting test, indicating the actual frame rate along with maximum number of frames and how long you would have to wait after taking the maximum number of frames before you could take another shot. The media used for these tests was a 1.0 GB SanDisk Extreme III SD card. Shutter speed was kept above 1/200 sec during these tests.
Continuous drive mode
The SD550 has a single continuous shooting modes, and a brief review image is displayed for each frame captured. We found the 2.0fps quoted speed to be perfectly accurate, though for some reasons the rate drops slightly at some lower resolutions, possibly due to the extra processing overhead incurred by reducing the file size before creating the JPEG.
Frames in a burst *1
|3072 x 2304 JPEG Super Fine||Continuous||2.1 fps||Unlimited||n/a|
|3072 x 2304 JPEG Fine||Continuous||2.0 fps||Unlimited||n/a|
|3072 x 2304 JPEG Normal||Continuous||2.0 fps||Unlimited||n/a|
|2592 x 1944 JPEG SuperFine||Continuous||1.7 fps||Unlimited||n/a|
|2048 x 1536 JPEG SuperFine||Continuous||2.0 fps||Unlimited||n/a|
|1600 x 1200 JPEG SuperFine||Continuous||1.9 fps||Unlimited||n/a|
|*1||In a single "burst" (finger held down on shutter release).|
|*2||In our extensive tests we could not get to the point - even after 50 or 60 shots - where the buffer caused the frame rate to drop or the shooting to pause significantly.|
Nothing to complain about here; not only does the SD550 manage to maintain a good 2.0 frames per second at most file sizes and quality settings, the buffering is so fast that you can shoot pretty much indefinitely, even at the top 7MP/Super Fine setting, as long as you have a fast enough SD card. It seems impossible to fill the buffer when using a fast card, meaning you can keep shooting for as long as you have the battery power and card capacity to do so.
File Write / Display and Sizes
Timings shown below are the time taken for the camera to process and "flush" the image out to the storage card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator went out. This means the timings also include the camera's processing time and as such are more representative of the actual time to "complete the task". The media used for these tests was a 1.0 GB SanDisk Extreme III SD card.
Time to store
Time to display
File size *1
Images on a *2
1.0 GB Card
|3072 x 2304 JPEG Super Fine||~1.1||~0.2||2,655 KB||322|
|3072 x 2304 JPEG Fine||~0.8||~0.2||1,522 KB||515|
|3072 x 2304 JPEG Normal||~0.6||~0.2||582 KB||1,068|
|2592 x 1944 JPEG SuperFine||~0.7||~0.2||1,647 KB||391|
|2048 x 1536 JPEG SuperFine||~0.6||~0.2||1,249 KB||607|
|1600 x 1200 JPEG SuperFine||~0.6||~0.2||823 KB||967|
|*1||All file sizes are an average of three files. As is the case with JPEG it's difficult to predict the size of an image because it will vary a fair amount depending on the content of the image (detail and noise).|
With write times averaging just over a second for a 7MP Fine JPEG, the SD550 is very fast indeed (at least 2.5MB/s). Note that if you shoot images in lower light (with longer exposures) the noise reduction system increases the processing time to around 1.2 seconds, during which time you will see the word 'busy' appear briefly on-screen. This is a camera that can make the most of a fast card, unlike most compact and ultra-compact models.