"Picky Details" for the Canon PowerShot A70 digital camera
(Timing, Power, and Storage Info)
Timing
Because they're such critical performance parameters (that are so seldom reported
on), I routinely measure both cycle times and shutter delay times, 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 A70:
NOTE: My qualitative characterizations of camera performance below (that is, "reasonably fast," "about average," etc.) are meant to be relative to other cameras of similar price and general capabilities. Thus, the same shutter lag that's "very fast" for a low-end consumer camera might be characterized as "quite slow" if I encountered it on a professional model. The comments are also intended as only a quick reference: If performance specs are critical for you, rely on the absolute numbers to compare cameras, rather than my purely qualitative comments.
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(secs) |
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| Power On -> First shot |
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Canon startup screen appears and lens extends forward. About average.
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| Shutdown |
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Lens retracts. About average.
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| Play to Record, first shot |
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Time until first shot is captured. About average.
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| Record to play |
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Time to display a large/fine file after capture. Fairly fast.
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| Shutter lag, full autofocus |
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First time is at full wide-angle, second is full telephoto. 0.8 seconds at wide angle is on the fast side of average, but 1.3 seconds at telephoto is slower than average. |
| Shutter lag, prefocus |
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Time to capture, after half-pressing shutter button. Quite fast.
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| Cycle Time, max/min resolution |
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First number is for large/fine files, second number is time for small/basic images. Times are averages. Both cycle times are very good. Buffer memory holds five frames at large/fine, over 100 at small/basic setting. After first five frames in large/fine mode, cycle time increases to just under 3 seconds (still not bad). |
| Cycle Time, continuous mode, max/min resolution |
(2.0/2.0 fps) |
First number is for large/fine, second is for small/basic files. Numbers beneath are corresponding frames per second. Same cycle time/frame rate regardless of image size, difference is in how many shots you can snap without pausing. Large/fine mode limits you to 6 frames, small/basic allows roughly 130. Like most cameras I've tested, the A70 pauses slightly longer between the first and second shots of a series than between subsequent ones. The delay between the first and second shots is about 0.75 seconds regardless of image size, before settling in to the 2.0 frame/second rate on subsequent shots. |
Overall, the A70 is a decently fast camera, the one exception being its full-autofocus shutter lag with the zoom set to telephoto focal lengths. Regardless of focal length though, its prefocus shutter lag is very fast. (This is the shutter delay after the camera has been prefocused by half-pressing and holding the shutter button before the exposure itself.) Cycle times are faster than average, and the camera has a five- to six-frame buffer memory when shooting large/fine images. Overall, a good performance for an inexpensive camera.
Power
The PowerShot A70 uses four AA batteries for power.
The table below shows the PowerShot A70's power consumption in various modes, and approximate run times for each, based a set of four NiMH AA cells with a (true, not advertised) 1600 mAh capacity. (This is actually a bit conservative these days, as AA cells are available with true capacities as high as 2000 mAh.)
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(@4.8 volts on the external power terminal) |
(4x1600 mAh NiMH AA cells) |
| Capture Mode, w/LCD |
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212 |
| Capture Mode, no LCD |
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21 hours (!) |
| Half-pressed shutter w/LCD |
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201 |
| Half-pressed w/o LCD |
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287 |
| Memory Write (transient) |
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| Flash Recharge (transient) |
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| Image Playback |
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6.5 hours (!) |
The PowerShot A70 shows really excellent power consumption and battery life, particularly when the LCD is left turned off. Alas, the rather tight optical viewfinder means that you'll have to rely on the LCD screen for critical framing, which drops the battery life from exceptional to merely excellent. Regardless of the A70's long battery life though, I still strongly recommend that you purchase several sets of high-capacity NiMH AA cells and a good charger to go along with them. To see which NiMH cells are best, see my battery shootout page. Read my review of the Maha C-204F charger, to learn why it's my longtime favorite.
Storage Capacity
The PowerShot A70 stores its photos on CompactFlash memory cards, and a 16MB card is included with the camera. (I strongly recommend buying at least a 64MB card, preferably a 128MB one, to give yourself extra space for extended outings.) The chart below shows how many images can be stored on the included 16MB card at each size/quality setting.
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Resolution/Quality 16MB Memory Card |
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| 2,048 x 1,536 | Images (Avg size) |
9 1,662KB |
17 928KB |
34 467KB |
| Approx. Compression |
6:1 | 10:1 | 20:1 | |
| 1,600 x 1,200 | Images (Avg size) |
15 1,043KB |
27 582KB |
54 295KB |
| Approx. Compression |
6:1 | 10:1 | 20:1 | |
| 1,024 x 768 | Images (Avg size) |
599KB |
336KB |
188KB |
| Approx. Compression |
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Images (Avg size) |
270KB |
164KB |
98KB |
| Approx. Compression |
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Download Speed
The PowerShot A70 connects to a host computer via a USB interface. Downloading
files to my 2.4 GHz Sony VAIO desktop (Windows XP), I clocked it at 572
KBytes/second. (Cameras with
slow USB interfaces run as low as 300 KB/s, cameras with fast ones run as
high as 600 KB/s.)
A70 Test Images
A70 Specifications
A70 "Picky Details"
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