Timing & Performance
Like all recent IXUS/SD models the SD850 feels very responsive, with the DIGIC III imaging processor doing a good job powering the camera's processes. The camera takes about a second to get ready for shooting and focusing is pretty snappy at around 0.4 sec (although naturally this can slow down in poor light, especially at the tele end of the lens). The shutter lag is pretty 'standard' at 0.1 seconds when using the LCD; not specifically quick, but in line with most of the competition. If you turn off the LCD and use the viewfinder the lag drops to 0.07 sec. So there is a slight (0.03s) lag in the live preview (something common to most cameras).
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. 4,600 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||1.0|
|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||0.9|
|Mode: Record to Play||1.7|
|Mode: Play to Record||1.6|
|Play: Magnify||To full magnification (10x)||0.9|
|Play: Image to Image||Time to display each saved image||0.3 *1|
|Play: Thumbnail view||3 x 3 thumbnails||0.1|
|Zoom from Wide to Tele||35 to 140 mm (4 x) full speed||1.5|
|Half-press Lag (Focus time)||Wide angle, single shot focus||~0.4 *2|
|Half-press Lag (Focus time)||Telephoto, single shot focus||~0.4 *2|
|Pre-focus Lag (S1>S2)||LCD live view||~0.1|
|Pre-focus Lag (S1>S2)||Viewfinder||~0.07|
|Full-press Lag (0->S2)||LCD live view, wide angle||~0.6|
|Off to Shot Taken||LCD live view||~1.8|
|Shot to Shot||Flash off||~1.3|
|Shot to Shot||Flash on ( red eye reduction on / off)||~3.2 / ~ 2.5|
|*1||Fancy transition effects disabled. You can also scroll through low res images very quickly by holding down the left or right key.|
|*2||Focus slows down in low light - to about 0.6 seconds at the wide end and 1.4 seconds at the tele end|
Continuous drive mode
Like most SD/Ixus series cameras the SD850 has a single continuous shooting mode that offers around 1.3 frames per second at all file size / quality settings. You can't see a preview when shooting bursts, but there is a brief review image displayed after each exposure. There appears to be no limit to how many pictures you can take in a single burst with a fast card (well, we gave up after a few minutes).
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. 1.3fps is actually a decrease relative to the SD850's predecessor (The SD700's 2fps) - as ever increasing sensor resolutions (and therefore file sizes) take their toll.
File writing / playback performance
The SD850 takes around 0.9 seconds to save a 4MB 8MP/Super Fine JPEG; pretty good going for a camera of this type - the SD850 will certainly benefit from using faster cards. Playback is also very speedy, with full size images taking only 0.4 sec 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 SD850 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 on the low side of average; approx 230 shots (CIPA standard) per charge, with the saving grace being that the majority of the power is drawn by the fairly large screen, and if you switch it off and use the optical viewfinder you can extend the battery life to as much as 700 shots per charge. Remember that using the continuous mode image stabilization or using the flash a lot will reduce these figures.