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"Picky Details" for the Pentax Optio 550 digital camera
(Timing, Power, and Storage Info)

Timing
I 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 Optio 550:

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.

Optio 550 Timings
Operation
Time
(secs)
Notes
Power On -> First shot
5.1
Lens extends, startup screen displays. Somewhat slower than average.
Shutdown
3.96
Lens retracts a bit slower than average.
Play to Record, first shot
1.03
Time until first shot is captured. Quite fast.
Record to play
3.42/1.14
Time to display a large/fine file after capture. First time is immediately after capture, second time is after camera has finished writing the image to the memory card.
Shutter lag, full autofocus
1.17/1.14
First time is for wide angle, second is for telephoto lens setting. Both are on the slow side of average. (Average is between 0.8 and 1.0 seconds.)
Shutter lag, manual focus
0.389
Time to capture in manual focus mode. A bit faster than average. (Average is about 0.5 seconds.)
Shutter lag, prefocus
0.127
Time to capture, after half-pressing shutter button. Faster than average. (Average for prefocus lag used to be 0.3 seconds, these days is more like 0.18 or so.)
Cycle Time, max/min resolution
1.69/1.50
First number is for large/fine files, second number is time for small/basic images. Very (!) fast for a 5 megapixel camera. The buffer holds 5 large/fine frames before the camera has to wait for the memory card. In small/basic mode, the camera writes to the card as it goes along, so the cycle time never slows.
Cycle Time, continuous mode, max/min resolution
0.92/0.69
1.09/1.44 fps
Top numbers are cycle times for large/fine and small/basic files. Numbers beneath are corresponding frames per second. The camera captured five frames in large/fine mode before slowing, and 175 (!) in small/basic mode. Once the buffer was full, it took 16 seconds for it to clear after a large/fine sequence, 170 seconds after the small/fine.

 

The Optio 550 is a bit of a mixed bag when it comes to speed, as it starts up and shuts down somewhat slowly, and it's full-autofocus shutter lag time isn't too impressive. On the other hand, it's much faster than average from shot to shot, and has a healthy buffer memory, with room for 5 frames at its maximum image size and quality setting. It's prefocus time is quite fast as well. Continuous-mode cycle times are a little sluggish given how fast it is in other modes, but the large buffer is a plus. Overall, a pretty fast little camera, particularly in prefocus mode and from shot to shot.

 

Power
The Optio 550 uses a single (fairly hefty) lithium-ion battery pack for its power source. The table below shows the Optio's power consumption in various modes, and approximate run times for each, based a single lithium-ion battery pack with a (true, not advertised) 1800 mAh capacity:

 

Operating Mode
Power
(@4.5 volts on the external power terminal)
Est. Minutes
(3.7 1800 lithium-ion pack)
Capture Mode, w/LCD
810 mA
110
Capture Mode, no LCD
661 mA
134
Half-pressed shutter w/LCD
710 mA
125
Half-pressed w/o LCD
570 mA
156
Memory Write (transient)
696 mA
n/a
Flash Recharge (transient)
1417 mA
n/a
Image Playback
376 mA
236

These are better than average run times for a relatively compact digicam. I'd still strongly recommend purchasing a second battery along with the camera though, as digicam batteries invariably run out at the worst possible moment.

Storage Capacity
The Optio 550 stores its photos on SD/MMC memory cards, and a 16MB card is included with the camera. (I strongly recommend buying at least a 64MB card or larger, given the 550's high maximum resolution and conservative JPEG compression ratios.) The chart below shows how many images can be stored on the included 16MB card at each size/quality setting.

 

Image Capacity vs
Resolution/Quality
16 MB Memory Card
TIFF
Fine
Normal
Basic
2,592 x 1,944 Images
(Avg size)
1
15.1 MB
4
3,556 KB
8
1,829 KB
14
1,085 KB
Approx.
Compression
1:1 4:1
8:1
14:1
2,048 x 1,536 Images
(Avg size)
n/a
7
2,133 KB
13
1,185 KB
19
810 KB
Approx.
Compression
n/a
4:1
8:1
12:1
1,600 x 1,200 Images
(Avg size)
n/a
12
1,280 KB
21
762 KB
28
557 KB
Approx.
Compression
n/a
4:1
8:1
10:1
1,024 x 768
Images
(Avg size)
n/a
26
610 KB
47
337 KB
59
270 KB
Approx.
Compression
n/a
4:1
7:1
9:1
640 x 480
Images
(Avg size)
n/a
55
287 KB
86
186 KB
105
152 KB
Approx.
Compression
n/a
3:1
5:1
6:1

 

Download Speed
The Optio 550 connects to a host computer via a USB interface. Downloading files to my Sony VAIO desktop, 2.4 GHz Pentium IV, running Windows XP ("VAIO"), I clocked it at 573 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.)

 

O550 Review
O550 Sample Pictures
O550 Specifications
O550 "Picky Details"
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