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"Picky Details" for the Canon SD550 digital camera
(Timing, Power, and Storage Info)

Timing

When you press the shutter release on a camera, there's usually a lag time or delay before the shutter actually fires. This corresponds to the time required for the autofocus and autoexposure mechanisms time to do their work, and can amount to a fairly long delay in some situations. Since this number is rarely reported on (and even more rarely reported accurately), and can significantly affect the picture taking experience, I routinely measure both shutter delay and shot to shot cycle times for all cameras I test, using a test system I designed and built for the purpose. (Crystal-controlled, with a resolution of 0.001 second.) Here are the numbers I collected for the Canon SD550:

Canon SD550 Timings
Operation	Time (secs)	Notes
Power On -> First shot	1.0	LCD turns on and lens extends forward.
Shutdown	1.7 - 3	First time is time to retract lens, second time is worst-case buffer-clearing time.
Play to Record, first shot	1.2	Time until first shot is captured.
Record to play	2.1 / 1.6	First time is that required to display a large/fine file immediately after capture, second time is that needed to display a large/fine file that has already been processed and stored on the memory card.
Shutter lag, full autofocus	0.45 / 0.44	First time is at full wide-angle, second is full telephoto.
Shutter lag, prefocus	0.07	Time to capture, after half-pressing shutter button.
Cycle Time, max/min resolution	1.28 / 1.27	First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. In both modes, shoots this fast indefinitely, clearing the buffer after each shot.
Cycle Time, Flash exposures	8	Flash at maximum power output.
Cycle Time, continuous mode, max/min resolution	0.51 / 0.53 (1.95 / 1.9 fps)	First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. In both modes, shoots this fast indefinitely, clearing the buffer after each shot.

Power

The Canon SD550 uses a custom rechargeable LiIon battery for power.

Operating Mode	Battery Life
Still-image capture mode backlight on	150 images
Still-image capture mode no backlight	600 images
Image playback backlight on	3 hours

The PowerShot SD550 uses a custom rechargeable 790mAh Lithium Ion battery for power. The table above shows maximum number of photos and playback time, based on the CIPA standard.

Download Speed

The Canon SD550 connects to a host computer via a USB interface. Downloading files to my Sony desktop running Windows XP (Pentium IV, 2.4 GHz), I clocked it at 3201 KBytes/second. (Cameras with slow USB interfaces run as low as 300 KB/s, cameras with fast v1.1 interfaces run as high as 600 KB/s. Cameras with USB v2.0 interfaces run as fast as several megabytes/second.)

SD550 Review
SD550 Test Images
SD550 Specifications
SD550 "Picky Details"
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