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"Picky Details" for the Canon PowerShot A85 digital camera
(Timing, Power, and Storage Info)

 

Timing

When you press the shutter release on a camera, there's usually a lag time or delay before the shutter actually fires. This corresponds to the time required for the autofocus and autoexposure mechanisms time to do their work, and can amount to a fairly long delay in some situations. Since this number is rarely reported on (and even more rarely reported accurately), and can significantly affect the picture taking experience, I routinely measure both shutter delay and shot to shot cycle times for all cameras I test, using a test system I designed and built for the purpose. (Crystal-controlled, with a resolution of 0.001 second.) Here are the numbers I collected for the Canon PowerShot A85:

Canon PowerShot A85 Timings
Operation
Time
(secs)
Notes
Power On -> First shot
2.6
LCD turns on and lens extends forward.
Shutdown
2.2 - 27
First time is time to retract lens, second time is worst-case buffer-clearing time.
Play to Record, first shot
1.6
Time until first shot is captured.
Record to play
1.7 / 1.1
First time is that required to display a large/fine file immediately after capture, second time is that needed to display a large/fine file that has already been processed and stored on the memory card.
Shutter lag, full autofocus
0.75/0.96
First time is at full wide-angle, second is full telephoto.
Shutter lag, prefocus
0.074
Time to capture, after half-pressing shutter button.
Cycle Time, max/min resolution

2.06 /
2.07

First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. In large/fine mode, shoots 4 shots this fast, then slows to about 4.2 seconds apart, and clears the buffer in 11 seconds. In TV mode, maintains this rate for over 50 shots, and clears the buffer in 16 seconds.
Cycle Time, continuous mode, max/min resolution 0.71 / 0.67
(1.4 / 1.5 fps)
First number is for large/fine files, second number is time for "TV" size images. Times are averages. In large/fine mode, shoots 4 shots this fast, then slows to about 2.2 seconds apart, and clears the buffer in 13 seconds. In TV mode, shoots 71 shots this fast, then slows to about 1 second apart, and clears the buffer in 25 seconds.

 

Power

The Canon PowerShot A85 uses four AA batteries for power.

Operating Mode
Power
(@3.4 volts on the external power terminal)
Est. Minutes
(four 1600 mA cells)
Capture Mode, w/LCD
448 mA
229
Capture Mode, no LCD
104 mA
983
Half-pressed shutter w/LCD
490 mA
209
Half-pressed w/o LCD
385 mA
266
Memory Write (transient)
604 mA
n/a
Flash Recharge (transient)
854 mA
n/a
Image Playback
218 mA
470



Storage Capacity

The Canon PowerShot stores its photos on Compact Flash memory cards, and a 32 MB card is included with the camera. (I strongly recommend buying at least a 64 MB card, preferably a 128 MB one, to give yourself extra space for extended outings.) The chart below shows how many images can be stored on the included 32 MB card at each size/quality setting.

Image Capacity vs
Resolution/Quality
32 MB Memory Card
Fine Normal
Basic
2,272 x 1,704 Images
(Avg size)
15
2.1 MB
27
1.2 MB
54
593 KB
Approx.
Compression
6:1 10:1 20:1
1,600 x 1,200 Images
(Avg size)
30
1.0 MB
54
587 KB
103
310 KB
Approx.
Compression
6:1 10:1 19:1
1,024 x 768 Images
(Avg size)
53
603 KB
93
342 KB
163
196 KB
Approx.
Compression
4:1 7:1
12:1
640 x 480
Images
(Avg size)
115
277 KB
178
179 KB
280
114 KB
Approx.
Compression
3:1 5:1
8:1

 

Download Speed

The Canon PowerShot connects to a host computer via a USB interface. Downloading files to my Sony desktop running Windows XP (Pentium IV, 2.4 GHz), I clocked it at 484 KBytes/second. (Cameras with slow USB interfaces run as low as 300 KB/s, cameras with fast v1.1 interfaces run as high as 600 KB/s. Cameras with USB v2.0 interfaces run as fast as several megabytes/second.)

A85 Review
A85 Test Images
A85 Imatest Results
A85 Specifications
A85 "Picky Details"
Up to Imaging Resource digital cameras area

 

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