Casio Exilim EX-Z850 Review
Timing & Performance
No real complaints at all here - like the Z750 before it, the Z850 is as speedy as the best cameras in its class and rarely - if ever - gets in the way of taking pictures. The important stuff - focus speed, shutter lag, shot-to-shot times and so on are excellent, and overall the camera feels very responsive indeed in use. It's also nice to see Casio continuing to innovate, offering for example a flash burst mode (unique as far as I know on this type of camera).
All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 3264 x 2448 Fine JPEG Super Fine image (approx. 4,800 KB per image). The media used for these tests was a 1.0GB SanDisk Extreme III SD card.
|Power: Off to Record||1.3|
|Power: Off to Play||Direct mode (lens not extended) *1||1.1|
|Power: Record to Off||All activity ceased||1.3|
|Power: Play to Off||When buffer is empty, lens retracted||~0.4|
|Power: Play to Off||When buffer is empty, lens extended||1.3|
|Record Review||Image displayed||~0.8|
|Mode: Record to Play||~0.3|
|Mode: Play to Record||Lens already extended||~0.5|
|Mode: Play to Record||Lens not extended||1.3|
|Play: Magnify||To full magnification (8x)||2.0|
|Play: Image to Image||Time to display each saved image *2||~ 0.2|
|Play: Thumbnail view||3 x 3 thumbnails||~0.3|
|Zoom from Wide to Tele||38 to 114 mm (3 x)||0.9|
|Half-press Lag (0->S1)||Wide angle, Spot AF *2||~0.2|
|Half-press Lag (0->S1)||Telephoto, Spot AF *2||~0.3|
|Half to Full-press Lag (S1->S2)||LCD live view||~0.09|
|Half to Full-press Lag (S1->S2)||Viewfinder||~0.03|
|Full-press Lag (0->S2)||LCD live view, wide angle||~0.2|
|Off to Shot Taken||LCD live view||~1.5|
|Shot to Shot||Flash off||~1.3|
|Shot to Shot||Flash on (with red eye reduction off)||~1.8|
|Shot to Shot||Flash on (with red eye reduction on)||~3.5|
|*1||To power up directly into play mode (without extending the lens) you have to enable this feature in the setup menu. You can power up normally and switch to playback in about 1.6 secs.|
|*2||Holding down the left or right scroll buttons lets you zip through low-res preview images at around 10 frames per second.|
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 1.0GB SanDisk Extreme III SD card. Shutter speed was kept above 1/160 sec during these tests.
Continuous drive mode
The Z850 improves on its predecessor's burst mode by adding a 'high speed' option (though the limit of 3 shots per burst is a bit restrictive) - the standard no-limit continuous mode offers roughly the same (1 frame per second) performance as the Z750. Another welcome addition is a pretty unique 'Flash Continuous' mode, that allows a 3-shot burst to be taken with flash (albeit at a reduced power, so it's better for subjects not too far away).
There are two other modes in the drive menu, 'Zoom Continuous', which saves two shots when you press the shutter, one 'normal' (full res) and one zoomed in (reduced resolution). I fail to see the point of this, though I'm sure someone will find one. The second mode, Multi Continuous, takes a single burst of 25 images in a period of around 1.5 seconds, and combines them into a single 1600x1200 frame.
Frames in a burst *1
|3264 x 2448 (8MP) JPEG *3||Continuous||1.0 fps||unlimited||n/a|
|3264 x 2448 (8MP) JPEG *3||Cont-High speed||3.3 fps||3||~ 2.8s|
|3264 x 2448 (8MP) JPEG *3||Cont-Flash||3.3 fps||3||~ 3.4s|
|2816 x 2112 (6MP) JPEG *3||Continuous||1.1 fps||unlimited||n/a|
|2816 x 2112 (6MP) JPEG *3||Cont-High speed||3.3 fps||3||~ 2.0s|
|2816 x 2112 (6MP) JPEG *3||Cont-Flash||3.3 fps||3||~ 2.5s|
|2304 x 1728 (4MP) JPEG *3||Continuous||1.2 fps||unlimited||n/a|
|2304 x 1728 (4MP) JPEG *3||Cont-High speed||3.3 fps||3||~ 1.9s|
|2304 x 1728 (4MP) JPEG *3||Cont-Flash||3.3 fps||3||~ 2.5s|
|*1||In a single "burst" (finger held down on shutter release).|
|*2||Once the buffer is full the Z850 will pause for between 1.9 and 2.5 seconds before another burst of shots can be taken - most of this time is taken up with the process of autofocus and auto exposure (and flash recycling in Flash Continuous mode).|
|*3||Results are identical for FINE / NORMAL and ECONOMY JPEG settings.|
Although it won't win any awards for continuous shooting, the Z850 is definitely an improvement on its predecessor, and the buffering is fast enough to allow unlimited shooting at the slower rate. The Continuous Flash mode is very useful in social situations. Note that we tested down to 2MP at all JPEG settings and the results are virtually identical for all settings.
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 1.0GB SanDisk Extreme III SD card.
Time to store
Time to display
File size *1
Images on a *2
1.0 GB Card
|3264 x 2448 (8MP) JPEG Fine *3||1.9||< 0.2||4,800 KB||199|
|3264 x 2448 (8MP) JPEG Normal *3||1.4||< 0.2||2,720 KB||295|
|3264 x 2448 (8MP) JPEG Economy *3||1.3||< 0.2||1,315 KB||573|
|2816 x 2112 (6MP) JPEG Fine||1.6||< 0.2||3,640 KB||265|
|2304 x 1728 (4MP) JPEG Fine||1.5||< 0.2||2,460 KB||396|
|1600 x 1200 (2MP) JPEG Fine||1.4||< 0.2||1,160 KB||799|
|*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).|
|*3||We also tested the 8MP 3:2 mode, and despite the slightly smaller files the time to store is marginally longer.|
At around 1.9 seconds to write and process a 4.8MB JPEG image, the Z850 is in the middle ground for a camera in this class (2.5MB/s), but plenty fast enough for everyday use - the fast buffering helps, and i never found the camera unable to take a shot when I wanted to.
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