Timing & Performance
Like all recent IXUS/SD models the SD870 feels very responsive indeed, and in most respects performance is almost identical to the SD800 (some things are a little quicker, some a little slower). Again the shutter lag when using the LCD could be a little shorter, and the lack of an optical finder means you can't really avoid it (the actual lag is mainly caused by the LCD). Compared to many ultra compacts, however, the SD870 IS rarely, if ever, struggles to keep up with you.
All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 3264 x 2448 Fine JPEG image (approx. 4,000 KB per image). The media used for these tests was a 1.0 GB Sandisk Extreme III card.
|Power: Off to Record||With startup animation disabled||0.9|
|Power: Off to Play||Image displayed||1.0|
|Power: Record to Off||All activity ceased||1.5|
|Power: Play to Off||When buffer is empty, lens retracted||0.2|
|Power: Play to Off||When buffer is empty, lens extended||1.1|
|Record Review||Image displayed||0.8|
|Mode: Play to Record||1.6*1|
|Play: Magnify||To full magnification (10x)||0.9|
|Play: Image to Image||Time to display each saved image||0.3 *2|
|Play: Thumbnail view||3 x 3 thumbnails||0.6|
|Zoom from Wide to Tele||28 to 105 mm (3.7 x)||1.3|
|Half-press Lag (Focus time)||Wide angle||~0.3|
|Half-press Lag (Focus time)||Telephoto||~0.4 *3|
|Pre-focus Lag (S1>S2)||LCD live view||~0.1 *4|
|Full-press Lag (0->S2)||LCD live view, wide angle||~0.4|
|Off to Shot Taken||LCD live view||1.4|
|Shot to Shot||Flash off||1.7|
|Shot to Shot||Flash on ( red eye reduction on / off)||2.5 / 3.0 *5|
|*1||This includes the time for the mode change animation to finish (live preview appears after around a second, the animation can be skipped by pressing the shutter button).|
|*2||With transition effects turned off - these increase the time|
|*3||Focus at the tele end slows down in low light - to about 0.6 seconds|
|*4||Actual shutter lag appears to make up around 0.04 of this delay, with LCD lag making up the rest|
|*5||Flash recycle time will vary widely according to shooting distance|
Continuous drive mode
Like most SD/IXUS series cameras the SD870 has a single continuous shooting mode, in this case offering around 1.3 frames per second at all file size / quality settings - slightly slower than the SD800, but still useful enough. You can't see a preview when shooting bursts, but there is a brief review image displayed after each exposure. The camera will continue shooting until long after you get bored or whatever you were shooting has packed up and gone home for the evening.
Although it's unlikely that many users of a camera such as this will need to shoot such long sequences, it's nice to know you can if you want to. There are competing cameras that will shoot faster, but only for short bursts, so if this is a feature you feel you need, then it's worth having a think about whether it's speed or longevity of shooting that you're after.
File writing / playback performance
The SD870 takes around 1.1 seconds to process and save a ~4.0MB 8MP/Super Fine JPEG (exact size depends on the complexity of the image being shot); which is by no means tardy. Given this relatively fast performance, it makes sense to use a fast card to prevent adding a bottleneck to the process. Playback is also very speedy, with full size images taking under a third of a second to display (if you use the fancy transition options it takes a little longer to scroll through images, but it sure looks nice). If you want to whiz through hundreds of saved shots you can hold down the left or right arrow key and the SD870 will scroll through low res previews of the images on your card at about 10 per second.
Battery life, like most models in the SD range, is acceptable enough, at approx 270 shots per charge (CIPA standard) - identical to the SD800 IS before it, which should be good for a day's photography for most users. That said, without an optical viewfinder you can't eke out a bit more life by not using the screen and, of course, using the continuous mode image stabilization or flash a lot will further reduce this figure.