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Canon PowerShot A85
"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.)
|