"Picky Details" for the Canon PowerShot A520 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 A520:
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||
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(secs) |
|
| Power On -> First shot | |
LCD turns
on and lens extends forward. About average. |
| Shutdown | |
First time is time to retract
lens, second time is worst-case buffer-clearing time. First time is
fairly fast. Second time is long, but corresponds to clearing 100 small/basic
images from the buffer memory after a long sequence in continuous shooting
mode. |
| Play to Record, first shot | |
Time until
first shot is captured. About average. |
| Record to play | |
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. About average. |
| Shutter lag, full autofocus | |
First time is at full wide-angle, second is full telephoto. Right in the middle of the "average" range. |
| Shutter lag, manual focus | 0.535 |
A little slow by current standards. |
| Shutter lag, prefocus | 0.074 |
Time to capture, after half-pressing shutter button. Very fast. |
| Cycle Time, max/min resolution | 2.51 / 2.6 |
First number is for large/fine files, second number is time for "TV" mode (640x480) images. Times are averages. In large/fine mode, shoots four frames this fast, then slows to about 3.9 seconds per shot. In TV mode, continues at this rate indefinitely. Buffer clears in 7 seconds in large/fine mode, 5 seconds in TV mode. About average for a camera in this price/performance bracket. |
| Cycle Time, continuous mode, max/min resolution | 0.68 / 0.61 (1.47 / 1.64 fps) |
First number is for large/fine files, second number is time for "TV" mode images. Times are averages. In large/fine mode, shoots four frames this fast, then slows to about 1.7 seconds per shot. In TV mode, shoots 85 frames this fast, then slows just a little to about .77 seconds per shot. Buffer clears in 6 seconds in large/fine mode, 12 seconds in TV mode. A reasonable rate for a camera in the A520's price/performance bracket, with a reasonable buffer capacity for large/fine files. |
Average cycle time and shutter lag numbers. The Canon PowerShot A520's timing performance is solidly in the middle of the range for cameras in its price/performance class. Its full-autofocus shutter lag range of 0.88 - 0.94 second falls within the 0.8 - 1.0 second range that's typical for consumer digital cameras. (Although still way too slow in my opinion - Shutter lag is one area where most manufacturers really need to apply more development effort.) Shot to shot cycle times are workmanlike if not impressive, at 2.5 seconds in single shot mode, and 0.68 seconds (1.47 frames/second) in continuous mode, both times corresponding to shooting large/fine images.
Power
The Canon PowerShot A520 uses 2 AA batteries for power. Following are the power drains I measured in various operating modes, and the projected run time, based on NiMH rechargeable batteries with 1600 mAh true capacity.
| |
(@3.1 volts on the external power terminal) |
(two 1600 mA cells) |
| Capture Mode, w/LCD | |
|
| Capture Mode, no LCD | |
|
| Half-pressed shutter w/LCD | |
|
| Half-pressed w/o LCD | |
|
| Memory Write (transient) | |
|
| Flash Recharge (transient) | |
|
| Image Playback | |
|
Very good battery life, particularly for a 2-AA cell camera. Considering
that it's powered by only two AA cells, the Canon PowerShot A520 showed very
good battery life. Based on the "standard" 1600 mAh NiMH cells that
I've used as a basis of comparison for the last several years, worst-case run
time is projected at 136 minutes in record mode with the LCD turned on. Playback
run time is 348 minutes, and run time in record mode with the LCD turned off
is an exceptional 12.8 hours. (Don't get too excited though, the relatively
inaccurate viewfinder on the A520 will have you using the LCD display to frame
your shots most of the time.) Note though, that high-capacity NiMH cells these
days have true capacities of well over 2000 mAh, so you can expect worst case
run times more on the order of 170 minutes, just shy of three hours. I do still
highly recommend that you pick up a couple of sets of high-capacity
rechargeable AA batteries and a good-quality
battery charger. - This will be an investment that pays itself back many
times over the life of the camera.
Storage Capacity
The Canon PowerShot A520 stores its photos on SD/MMC memory cards, and a 16 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 16 MB card at each size/quality setting.
| Resolution/Quality 16 MB Memory Card |
Fine | Normal | |
|
| 2272 x 1704 | Images (Avg size) |
7 2.1 MB |
13 1.2 MB |
26 598 KB |
| Approx. Compression |
5:1 | 9:1 | 19:1 | |
| 1600 x 1200 | Images (Avg size) |
15 1.1 MB |
26 598 KB |
50 316 KB |
| Approx. Compression |
5:1 | 10:1 | 18:1 | |
| 1024 x 768 | Images (Avg size) |
26 605 KB |
45 349 KB |
80 199 KB |
| Approx. Compression |
4:1 | 7:1 | 12:1 |
|
| |
Images (Avg size) |
56 283 KB |
87 183 KB |
116 KB |
| Approx. Compression |
3:1 | 5:1 | |
|
Download Speed
The Canon PowerShot A520 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 475 KBytes/second, a relatively unimpressive rate by current standards. (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.) You probably won't need a card reader with the A520, but you might find yourself wishing for one if you use a large memory card with it.
A520 Test Images
A520 Specifications
A520 "Picky Details"
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