Timings & File Sizes

The Optio S is nothing short of a wow for an ultra-compact digital camera. Power on takes just 2.3 seconds and you can go from powered off to having taken a shot in just 2.8 seconds. The camera's auto focus system is superb, in average light the camera didn't take more than a second to auto focus, even faster if you go for the Spot AF option. It recorded some of the fastest Total LAG (a complete depression of the shutter release, no pre-focus) of any digital camera we've reviewed. That means that this little Pentax should feel as fast as a compact film camera. Not without my gripes however the camera is let down by a lack of buffering, this means that you can't take the next shot until the last has been written, that's worth bearing in mind.

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 2048 x 1536 JPEG image (approx. 1,800 KB per image). The media used for these tests was a 128 MB SanDisk SD card.

Action Details Time, seconds
Power: Off to On Lens extension 2.3
Power: On to Off Lens extended 2.1
Mode: Play mode Image displayed 0.7
Play: Magnify To 4x magnification (Quick Zoom enabled) 2.7
Play: Thumbnail view Nine image displayed (3x3) 1.3

Action Details Time, seconds
Zoom from Wide to Tele Full zoom from 35 mm to 105 mm (3 x) 1.5
Auto Focus LAG Wide angle, Spot (single) AF area 0.5 - 0.8
Auto Focus LAG Telephoto, Spot (single) AF area 0.5 - 0.8
Auto Focus LAG Wide angle, Multiple AF area 0.8 - 1.0
Auto Focus LAG Telephoto, Multiple AF area 0.8 - 1.0
Shutter Release LAG Using Viewfinder <0.1
Shutter Release LAG Using LCD Monitor 0.1
Total LAG Wide angle 0.5
Total LAG Telephoto 0.5
Off to Shot Taken Wide angle 2.8
Shot to Shot *1 Wide angle, 2048 x 1536 JPEG 4.4
Shot to Shot *1 Wide angle, 1600 x 1200 JPEG 2.8

*1 As noted earlier in this review the Optio S does not allow you to take another shot until the last shot has been fully written to the SD card. This is a poor implementation of buffering. This Shot to Shot timing is therefore dependent on the size of the image stored.

Auto Focus LAG is (roughly) the amount of time it takes the camera to autofocus (a half-press and hold of the shutter release button), this timing is normally the most variable as its affected by the subject matter, current focus position, still or moving subject etc. This timing is an average.

Shutter Release LAG is the amount of time it takes to take the shot from the moment you fully depress the shutter release button, measured both as a time including auto focus and a time assuming you have already pre-focused by holding a half-press of the shutter release.

File Write / Display and Sizes

Timings shown below are the time taken for the camera to process and "flush" the image out to the SD card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator LED beside the viewfinder stopped blinking. This means the timings also include the cameras processing time and as such are more representative of the actual time to "complete the task". The media used for these tests was a 128 MB SanDisk SD card.

Image Type Time to write

Time to display
File size *1
Images on a *2
128 MB SD
2048 x 1536 JPEG 4.1 <0.5 1,800 KB 61
2048 x 1536 JPEG 2.8 <0.5 1,000 KB 111
1600 x 1200 JPEG 2.5 <0.5 650 KB 175
1024 x 768 JPEG 1.8 <0.5 260 KB 409

*1 All file sizes are an average of three files. As is the case with JPEG it's difficult to predict the size of an image because it will vary a fair amount depending on the content of the image (especially the amount of detail captured). For example, take a photograph of a fairly empty wall and you'll get a small JPEG, take a photograph of a bush with a lot of detail and you'll get a larger image. File sizes here are closer to the later, the larger size of file you should expect.
*2 Camera estimation.

The three star JPEG compression is very little compression at all, it generates very large images (considering the three megapixel resolution) and thus means long write times and big storage requirements. My advice would be to stick to the two star JPEG compression, hardly any visible artifacts, a reasonable file size and write times. It's a shame there's no 'next shot buffer'. Playback is instant, indeed if you hold down the left or right buttons on the 4-way controller the camera zips through images at about 3 frames per second.

Low Light Auto Focus

This test is designed to measure the minimum amount of light under which the camera can still focus. The focus target is our lens distortion test chart (shown here on the right), camera is positioned exactly 2 m (6.6 ft) away.

Light levels are gradually dropped until the camera can no longer focus. This is carried out at both wide angle and telephoto zoom positions (as more light reaches the focusing systems with a larger aperture).

This test target is the optimum type of subject for most "contrast detect" AF systems (as it has a vertical line at its center), you should consider the results below the best you could expect to achieve.

Lens position Aperture Lowest light focus
Wide angle (35 mm) F2.6 1.8 EV (8.7 Lux, 0.81 foot-candle)
Telephoto (105 mm) F4.8 2.0 EV (10.0 Lux, 0.93 foot-candle)

Light intensity (Lux) = 2.5 x 2^EV (@ ISO 100), 10.76391 Lux = 1 foot-candle (fc)

I was a little surprised to see the Optio S not performing as well as we would have hoped. The camera did require a reasonable amount of light before gaining a good AF lock.

Battery life

We ran the camera through our new battery life test. This test is designed to be fair and comparative to each camera and battery type:

  • Take 4 shots without flash
  • Wait 2 minutes (50% of the time powering the camera off)
  • Take 1 shot with flash
  • Wait 1 minute
  • Repeat

Batteries are fully discharged and recharged before the test and all cameras were reset to their factory default settings. Here are the results:

Compact / Ultra compact
Battery Power Battery life Number of shots
Kyocera S3 BP-800S 2.1 Wh 54 mins 95
Canon PowerShot S300 NB-1L 2.5 Wh 1 hr 26 mins 155
Pentax Optio 430 D-LI2 3.3 Wh 1 hr 33 mins 160
Olympus C-40Z 2 x AA NiMH 1600 mAh (GP) 3.6 Wh 1 hr 33 mins 165
Nikon Coolpix 3100 2 x AA NiMH 1600 mAh (GP) 3.6 Wh 1 hr 42 mins 175
Minolta DiMAGE F100 2 x AA NiMH 1600 mAh (GP) 3.3 Wh 1 hr 42 mins 175
Minolta DiMAGE X NP-200 2.8 Wh 1 hr 45 mins 180
Pentax Optio 330 D-LI2 3.3 Wh 1 hr 48 mins 185
Canon PowerShot S330 NB-1LH 2.5 Wh 1 hr 48 mins 185
Sony DSC-P71 2 x AA NiMH 1600 mAh (GP) 3.6 Wh 1 hr 50 mins 185
Kodak DX4900 2 x AA NiMH 1600 mAh (GP) 3.5 Wh 1 hr 51 mins 190
Sony DSC-P5 NP-FC10 2.4 Wh 1 hr 51 mins 190
Nikon Coolpix 3500 EN-EL2 4.1 Wh 1 hr 54 mins 195
Sony DSC-P9 NP-FC10 2.4 Wh 1 hr 59 mins 200
Nikon Coolpix SQ EN-EL2 3.7 Wh 2 hr 03 mins 210
Minolta DiMAGE Xt NP-200 2.8 Wh 2 hr 12 mins 225
Canon PowerShot S400 NP-1LH 2.5 Wh 2 hr 17 mins 230
HP Photosmart 812 2 x AA NiMH 1600 mAh (GP) 3.6 Wh 2 hr 21 mins 240
Nikon Coolpix 885 EN-EL1 4.8 Wh 2 hr 21 mins 240
Nikon Coolpix 775 EN-EL1 4.8 Wh 2 hr 27 mins 250
Canon PowerShot SD100 NB-3L 2.9 Wh 2 hr 29 mins 250
Pentax Optio S D-LI8 2.6 Wh 2 hr 33 mins 260
Nikon Coolpix 2500 EN-EL2 4.1 Wh 2 hr 33 mins 260
Fujifilm FinePix F601Z NP-60 3.7 Wh 2 hr 47 mins 275
Casio EXILIM EX-Z3 NP-20 2.5 Wh 2 hr 48 mins 285
Casio EXILIM EX-S3 NP-20 2.5 Wh 2 hr 48 mins 285
Olympus C-50Z LI-10B 4.0 Wh 2 hr 54 mins 295
HP Photosmart 935 2 x AA NiMH 1600 mAh (GP) 3.6 Wh 3 hr 09 mins 320
Canon PowerShot A70 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 5 hr 08 mins 515
Other test notes:
 • LCD monitor is left on during the battery test
 • The camera is powered off half of the time and left on half of the time (switch every 10 iterations)
 • There are now higher capacity AA NiMH batteries available, however in the interests of fair
    comparison we will continue to use our 1600 mAh test set

The Optio S lasted well, considering the tiny battery's relatively low 2.6 Wh capacity it provided a respectable 2.5 hours of life, more than we had expected. Indeed the only camera to better this on a similar battery pack is the Optio S' half-sibling the Casio EXILIM EX-Z3.