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Timing & Performance

It's rare these days to find a compact camera from a major manufacturer that isn't responsive in use and the G7 is no exception - this is one area where anyone upgrading from a G6 will find the new camera a big improvement. That said, there are a couple of areas where the G7 could never be described as 'class-leading'; focus and shutter lag.

The focus speed is perfectly acceptable, especially given the huge zoom range, but there are faster cameras on the market - even the S3 IS, with twice the zoom range, consistently beats it at the wide end of the zoom. The G7's autofocus is actually quite slow in low light or macro mode. Shutter lag when using the LCD is also a little disappointing (though to be fair I didn't personally notice any problems when out shooting; I don't really 'do' action). This is down to the lag in the live view itself (which is around 0.07 secs) - the time between pressing the shutter and taking the picture is a very short 0.05 seconds (approx) - so if you need to use the G7 on a 'hair trigger' - don't use the LCD screen.

Timing Notes

All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 3648 x 2736 Super-Fine JPEG image (approx. 4,300 KB per image). The media used for these tests was a 1.0GB SanDisk Extreme III SD card.

Action Details
Time, secs

Power: Off to Record

  1.4
Power: Off to Play Image displayed 1.6
Power: Record to Off Lens retracted and all activity ceased 1.6
Power: Play to Off When buffer is empty (lens extended) 1.4
Power: Play to Off When buffer is empty (lens already retracted) < 0.1
Record Review Image displayed 0.8
Mode: Record to Play   1.6
Mode: Play to Record   ~ 1.4
Play: Magnify To full magnification (10x) 0.9
Play: Image to Image Time to display each saved image (fade effect transition) ~ 0.5
Play: Image to Image Time to display each saved image (no effect) *1 ~ 0.2
Play: Thumbnail view 3 x 3 thumbnails 0.6

Action Details
Time, seconds
Zoom from Wide to Tele 35 to 210 mm (12 x) full speed 1.7
Half-press Lag (0->S1) Wide angle (AiAF or FlexiZone focus) ~ 0.45 *2
Half-press Lag (0->S1) Telephoto (AiAF or FlexiZone focus) ~ 0.6 *2
Half to Full-press Lag (S1->S2) LCD live view ~ 0.12 *3
Half to Full-press Lag (S1->S2) Optical Viewfinder ~ 0.05
Full-press Lag (0->S2) LCD live view, wide angle ~ 0.7
Off to Shot Taken LCD live view 2.5
Shot to Shot Flash off 1.7
Shot to Shot Flash on (red-eye reduction off) *4 2.1
Shot to Shot Flash on (red-eye reduction on) *4 2.2
*1 You can also hold down the left or right buttons and scroll very quickly through images at approx 5 frames per second.
*2 Under ideal conditions. The G7 focus slows down in low light at longer focal lengths and when shooting at or near the closest focus distance.
*3 With the flash on the shutter lag extends to around 0.5 seconds
*4 In this test the subject distance is only 3 feet (0.9 m) - the recycle time will increase at greater subject distances.

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).
 

(Prime AF/AE)
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)

Continuous mode

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. Media used for these tests was a 1.0GB SanDisk Extreme III SD card. Shutter speed was kept above 1/200 sec during these tests.

Continuous drive mode

The G7 has two continuous shooting modes (standard and AF-continuous), both of which allow you to shoot pretty much indefinitely (we gave up counting after about 70 shots) with a fast card. The Continuous AF mode shows the normal live preview between frames (and attempts to refocus between shots), but the normal Continuous mode only shows a very brief review image after each shot (no live preview), and the focus is fixed after the first shot. It's worth noting that the figures below (and those quoted by Canon) are only for ISO settings of under 400; at higher ISO's the frame rate drops to around half these values.

Image Type
Mode
Avg. frames
per sec
Frames in a burst *1
After
burst
*2
10MP/6MP/4MP Super-Fine Continuous 2.0 fps No limit n/a
10MP/6MP/4MP Super-Fine Continuous AF 1.2 fps *3 No limit n/a
10MP/6MP/4MP Super-Fine Continuous mode (flash on) 1.2 fps No limit n/a

*1 In a single "burst" (finger held down on shutter release).
*2 With the shutter release held down. With a fast card it is impossible to fill the buffer
*3 Average speed - it will slow down if the camera has trouble focusing

Not a lot to complain about - there are cameras with faster burst modes, but most limit you to a handful of shots before the buffer is full; the G7 keeps on going until the card - or battery - run out. What is very impressive is that you can - with a full battery and a fairly short subject distance - shoot continuously with the flash on at up to 1.2 frames per second; a real rarity.

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.

Image Type
Time to store
(secs)

Time to display
(secs)
*3

File size *1
(approx.)
Images on a *2
1.0GB Card
10MP JPEG Super-Fine ~1.5 ~0.2 4,300 KB 240
10MP JPEG Fine ~1.4  ~0.2 2,500 KB 399
10MP JPEG Normal ~1.2  ~0.2 1,200 KB 825
6MP JPEG Super-Fine ~1.5 ~0.2 2,600 KB 361
4MP JPEG Super-Fine ~1.6  ~0.2 1,900 KB 487
2MP JPEG Super-Fine ~1.5  ~0.2 850 KB 967
640 x 480 JPEG Super-Fine ~1.2  ~0.2 180 KB 3,644

*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).
*2 Camera estimation.
*3 With transition effects turned off

The G7 takes around 1.5 seconds to process and write a Super Fine 10MP JPEG; this (around 2.9MB/s) is not actually that fast by today's standards, and would seem to indicate that the DIGIC III processor is having to do a lot of work on those huge files. The camera will benefit from a fast card - most do - but you'll really notice it only if you tend to take a lot of shots quick succession, or to capture long movie clips.

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