Excellent speed for a consumer digital SLR.

The Canon XSi's start-up and shutdown times were very fast. Buffer clearing time depends on the image size and quality, burst length and how fast the card can be written to.

Mode switching is about average for an SLR, though switching from Record to Play was a bit on the slow side.

Full autofocus shutter response is quite fast for a consumer SLR, at 0.17 second. As is usually the case, the pre-flashes emitted to perform flash metering add some delay when the flash is used, raising full shutter lag with the flash to 0.33 second. "Prefocus" time was also quite fast, at 0.089 second (pre-focusing means half-pressing and holding down the shutter button before the final exposure). Continuous mode was a bit slower than full AF, at 0.192 second. Manual focus was almost as fast as pre-focused at 0.115 second.

Autofocus lag when using the Canon XSi's Live View mode is slower than when using the optical viewfinder, but is still quite fast. "Live mode" AF uses contrast detect method from image sensor data, and results in a 0.25 second lag. The XSi's "Quick mode" AF uses the same phase-detect AF sensor as is utilized when using the optical viewfinder, but the extra mirror flips required result in a 0.232 second lag, which while slightly faster than Live View mode, is still slower than with the optical viewfinder. Still, these numbers are comparable to some competitors' AF lag using just an optical viewfinder, so they are really quite good.

Shot-to-shot cycle times are also very good, at about 0.42 second per frame for large/fine JPEGs in single-shot mode, and the camera was able to capture 19 frames at this rate before slowing down. RAW mode was a little faster at 0.36 seconds per shot, but the Canon XSi had to slow down after 5 frames to flush to the card. Continuous speed is also very good, at 3.5 frames per second for 13 large/fine JPEGs or about 5 RAW files. The flash takes 3.17 seconds to recharge after a full-power shot, which is quite good considering its power.

Connected to a computer or printer with USB 2.0, download speeds are quite speedy as well.

Bottom line, the Rebel XSi is very responsive and quick on the draw, fast enough to capture fast-paced action from sports to wildlife. The Canon XSi is also perfectly suited for photographing active children or pets, and its fast shutter response means you won't miss a shot while waiting for the autofocus. Overall, very good results.

Battery
Average battery life for a lithium-ion SLR design.

The Canon XSi uses a custom rechargeable lithium-ion battery for power, and ships with a charger. Battery life is only about average for an SLR using the optical viewfinder (and drops significantly when using the Live View mode), so we recommend you pick up a spare battery and keep it freshly charged and on-hand for extended outings.

The table above shows the number of shots the camera is capable of (on either a fresh set of disposable batteries or a fully-charged rechargeable battery as appropriate), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))

Storage
The Canon XSi accepts SD/SDHC cards, though no card is included.

The table above shows the approximate capacity of a 1GB card, file sizes and compression ratios at each image size/quality setting. We strongly recommend buying a large capacity SD/SDHC memory card at least a 1GB card, preferably a 4GB or larger one, to give yourself extra space for extended outings or when shooting in RAW mode. (Check the shopping link above. Cards are really cheap these days, so there's no reason to skimp.)