"Picky Details" for the Pentax Optio 750Z 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 Pentax Optio 750Z:
| |
||
| |
(secs) |
|
| Power On -> First shot | |
LCD turns
on and lens extends forward. A little slow. |
| Shutdown | |
First time is time to retract
lens, second time is worst-case buffer-clearing time. First time is average,
second time is very slow, but corresponds to emptying the buffer of more
than 100 small/basic images in continuous 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. Rather slow. |
| Shutter lag, full autofocus | |
First time is at full wide-angle, second is full telephoto. About average. (Average is a range of 0.8 - 1.0 second.) |
| Shutter lag, prefocus | |
Time to capture, after half-pressing
shutter button. Quick enough to catch fast-breaking action, but slower
than average for prefocused operation.) |
| Cycle Time, TIFF, max resolution | 13.1 |
Times are averages. No buffer memory, all shots take this long. Slow, but actually not bad for 7-megapixel TIFF images. |
| Cycle Time, max/min resolution | 3.11 / 3.06 | First number is for large/fine files, second number is time for "TV" size images. Times are averages. Shoots 5 large/fine images at this rate, then slows to an irregular rate of about 4.7 seconds apart. In TV mode, shoots continuously at this speed. Buffer clears in 9 seconds for large/fine images, about 2 seconds for lowest resolution. Rather slow. |
| Cycle Time, continuous mode, max/min resolution | 1.4 / 1.16 (0.71 / 0.86 fps) |
First number is for large/fine files, second number is time for "TV" size images. Times are averages. Shoots 5 large/fine images at this rate, then slows to an irregular rate of about 3.3 seconds apart. In TV mode, shoots continuously at this speed. Buffer clears in 9 seconds for large/fine images, about 1 second for lowest resolution. Not very fast for a continuous mode. |
Average shutter response, slower than average cycle times. With full-autofocus shutter lag ranging from 0.84 - 0.93 second, it's solidly in the middle of the average range of shutter response. Its shutter response when "prefocused" (by half-pressing and holding down the shutter button prior to the shot itself) is fast enough to capture fleeting action, but at 0.22 second, is slower than average these days. Shot to shot cycle times are slower than average, a bit over 3 seconds between shots in single-shot mode, and fully 1.4 seconds for large/fine JPEG images in continuous mode.
Power
The Pentax Optio 750Z uses a custom rechargeable LiIon battery for power. Here
are the power drain numbers I measured in various operating modes, along with
projected run times based on the stated capacity of its battery pack.
| |
(@4.5 volts on the external power terminal) |
(1800 mA LiIon cell) |
| 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 | |
|
With a worst-case run time of 154 minutes in capture mode with the rear-panel LCD enabled, and 216 minutes in capture mode with the LCD turned off, the Pentax Optio 750's battery life is well above average. In playback mode, the camera should be able to run for over 5 hours on a freshly charged battery. While I always recommend purchasing an extra battery right along with your digital camera, the Pentax 750z's battery life is good enough that most users will probably be able to get by with just the battery pack that's included with the camera.
Storage Capacity
The Pentax 750z 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 128 MB card, preferably a 256 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.
| Resolution/Quality 32 MB Memory Card |
Fine | Normal | |
TIFF |
|
| 3056
x 2296 |
Images (Avg size) |
7 4.1 MB |
15 2.0 MB |
23 1.3 MB |
1 22.2 MB |
| Approx. Compression |
5:1 | 10:1 | 16:1 | - | |
| 2592
x 1944 |
Images (Avg size) |
10 2.9 MB |
21 1.5 MB |
33 945 KB |
2 15.5 MB |
| Approx. Compression |
5:1 | 10:1 | 16:1 | - | |
| 2048
x 1536 |
Images (Avg size) |
17 1.8 MB |
33 945 KB |
50 629 KB |
- |
| Approx. Compression |
5:1 | 10:1 | 15:1 | - | |
| 1600 x 1200 | Images (Avg size) |
28 1.1 MB |
55 579 KB |
74 430 KB |
- |
| Approx. Compression |
5:1 | 10:1 | 14:1 | - | |
| 1024 x 768 | Images (Avg size) |
60 607 KB |
107 344 KB |
148 197 KB |
- |
| Approx. Compression |
5:1 | 8:1 | 11:1 |
- | |
| |
Images (Avg size) |
128 278 KB |
175 180 KB |
115 KB |
- |
| Approx. Compression |
4:1 | 5:1 | |
- | |
Download Speed
The Pentax Optio 750z 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 805 KBytes/second, a very respectable rate. (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.)
O750Z Test Images
O750Z Specifications
O750Z "Picky Details"
Up to Imaging Resource digital cameras area
Follow Imaging Resource: