Timings & File Sizes

There's no getting away from the fact that the Optio 550 can feel a little slow. The major problem is the amount of time it takes to extend that big five times optical zoom lens, total startup time is virtually six seconds which is at least two seconds slower than most of the prosumer competition. It can be frustrating to see something interesting and then have to wait six seconds before being able to take the shot. Operationally the camera was average, with fairly good (although not blistering) auto focus speeds and a very good shot to shot times (with review switched off).

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 2592 x 1944 JPEG image (approx. 2,600 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 5.9
Power: On to Off Lens extended 4.2
Mode: Play mode Image displayed 1.2
Play: Magnify To 4x magnification (Quick Zoom enabled) 2.7
Play: Thumbnail view Nine image displayed (3x3) 1.8

Action Details Time, seconds
Zoom from Wide to Tele Full zoom from 37.5 mm to 187.5 mm (5 x) 1.9
Auto Focus LAG Wide angle, Spot (single) AF area 0.8 - 1.4
Auto Focus LAG Telephoto, Spot (single) AF area 0.8 - 1.5
Auto Focus LAG Wide angle, Multiple AF area 1.1 - 1.4
Auto Focus LAG Telephoto, Multiple AF area 1.4 - 2.0
Shutter Release LAG Using Viewfinder 0.1
Shutter Release LAG Using LCD Monitor *1 0.1 - 0.2
Total LAG Wide angle 0.8
Total LAG Telephoto 0.5
Off to Shot Taken Wide angle 6.0
Shot to Shot Wide angle 1.8

*1 We got varied results using the LCD monitor, about 50% of the test shots showed a 0.1 sec shutter release lag, about 50% showed 0.2 sec.

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.

Continuous modes

The table below shows the results of our continuous shooting test, indicating the actual frame rate along with maximum number of frames and how long you would have to wait after taking the maximum number of frames before you could take another shot. The media used for these tests was a 128 MB SanDisk SD card.

Image Type Frames per sec Max no.
of frames

Wait before
next shot

2592 x 1944 JPEG 1.1 fps 4 8.8 sec
2592 x 1944 JPEG 1.2 fps 9 5.7 sec
2048 x 1536 JPEG 1.3 fps 14 3.3 sec
1600 x 1200 JPEG 1.3 fps 22 2.8 sec
1024 x 768 JPEG 1.4 fps 56 2.4 sec

*1 In a single "burst" (finger held down on shutter release)
*2 You can take a frame as soon as there is space in the cameras internal buffer (writing continues "in the background").

A slower than expected performance for a camera aimed at the prosumer market. The buffer is also smaller than I would have expected, considering the slow frame rate the camera should really be able to buffer far more than it does. Disappointing.

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
2592 x 1944 TIFF 24.9 0.5 14,873 KB 8
2592 x 1944 JPEG 5.0 0.5 2,600 KB 36
2592 x 1944 JPEG 3.3 0.5 1,200 KB 71
2048 x 1536 JPEG 2.7 0.5 800 KB 109
1600 x 1200 JPEG 2.3 0.5 480 KB 170
1024 x 768 JPEG 1.8 0.5 220 KB 384

*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.

Three star quality full resolution images weigh in at a surprising 2.5 MB, the camera estimates just 36 images on a 128 MB SD card. The best compromise between quality and storage must be two star full resolution images at around 1.1 MB each. Playback is quick, if you hold down the left or right arrows on the 4-way controller images are displayed at about two 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 (37.5 mm) F2.8 1.5 EV (7.1 Lux, 0.66 foot-candle)
Telephoto (187.5 mm) F4.6 2.8 EV (17.4 Lux, 1.62 foot-candle)

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

The Optio 550 produced an average auto focus performance at wide angle and a below average performance at full telephoto. That big zoom lens clearly isn't making life easy for the AF system.

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:

Prosumer / SLR-Like
Battery Power Battery life Number of shots
Minolta DiMAGE 7 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 1 hr 14 mins 125
Minolta DiMAGE 5 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 1 hr 56 mins 195
Nikon Coolpix 5700 EN-EL1 4.8 Wh 2 hr 08 mins 215
Canon PowerShot S40 NB-2L 3.9 Wh 2 hr 13 mins 225
Minolta DiMAGE S304 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 18 mins 235
Canon PowerShot S45 NB-2L 3.9 Wh 2 hr 28 mins 240
Nikon Coolpix 4500 EN-EL1 4.8 Wh 2 hr 27 mins 250
Fujifilm FinePix 6900Z NP-80 4.1 Wh 2 hr 29 mins 250
Nikon Coolpix 990 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 30 mins 255
Nikon Coolpix 995 EN-EL1 4.8 Wh 2 hr 30 mins 255
Nikon Coolpix 5000 EN-EL1 4.8 Wh 2 hr 32 mins 260
Minolta DiMAGE 7Hi 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 33 mins 260
Canon PowerShot Pro1 BP-511A 10.2 Wh 2 hr 36 mins 265
Canon PowerShot S50 NB-2L 3.9 Wh 2 hr 39 mins 270
Minolta DiMAGE S404 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 39 mins 270
Sony DSC-V1 NP-FC11 2.8 Wh 2 hr 39 mins 270
Olympus C-7000 Zoom LI-12B 4.5 Wh 2 hr 44 mins 280
Nikon Coolpix 8700 EN-EL1 5.0 Wh 2 hr 45 mins 280
Minolta DiMAGE 7i 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 46 mins 270
Olympus E-20 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 2 hr 48 mins 285
Canon PowerShot G1 BP-511 8.1 Wh 3 hr 00 mins 300
Nikon Coolpix 5400 EN-EL1 4.8 Wh 3 hr 06 mins 315
HP Photosmart 850 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 3 hr 12 mins 325
Sony DSC-S75 NP-FM50 8.6 Wh 3 hr 15 mins 330
Nikon Coolpix 8800 EN-EL7 8.1 Wh 3 hr 27 mins 350
Fujifilm FinePix S602Z 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 3 hr 29 mins 350
Canon PowerShot G2 BP-511 8.1 Wh 3 hr 32 mins 355
Casio QV-4000 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 3 hr 38 mins 365
Olympus C-5050 Zoom 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 3 hr 48 mins 380
Casio EXILIM EX-P700 NP-40 4.5 Wh 3 hr 48 mins 385
Sony DSC-S85 NP-FM50 8.6 Wh 3 hr 50 mins 400
Sony DSC-F717 NP-FM50 8.6 Wh 4 hr 02 mins 405
Pentax Optio 750Z D-LI7 6.6 Wh 4 hr 03 mins 415
Sony DSC-V3 NP-FR1 4.4 Wh 4 hr 05 mins 415
Nikon Coolpix 8400 EN-EL7 8.1 Wh 4 hr 09 mins 420
Sony DSC-F707 NP-FM50 8.6 Wh 4 hr 20 mins 440
Fujifilm S7000 Zoom 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 4 hr 23 mins 445
Konica Minolta DiMAGE A2 NP-400 11.1 Wh 4 hr 26 mins 450
Canon PowerShot G3 BP-511 8.1 Wh 4 hr 32 mins 455
Canon PowerShot G5 BP-511 8.1 Wh 4 hr 33 mins 460
Pentax Optio 550 D-LI7 6.6 Wh 4 hr 36 mins 465
Minolta DiMAGE A1 NP-400 11.1 Wh 5 hr 02 mins 515
Leica Digilux 2 BP-DC1-E 10.1 Wh 5 hr 05 mins 515
Sony DSC-F828 NP-FM50 8.6 Wh 5 hr 28 mins 540
Fujifilm FinePix S5000 4 x AA NiMH 1600 mAh (GP) 7.7 Wh 5 hr 31 mins 555
Canon PowerShot G6 BP-511A 10.3 Wh 5 hr 38 mins 570
Olympus C-8080 WZ BLM-1 10.8 Wh 5 hr 52 mins 595
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

Pentax should be very pleased with the results above, the Optio 550 lasted far longer than we expected considering the 6.6 Wh capacity of its battery. The camera lasted just slightly longer than Canon's PowerShot G3 and so takes the crown as the longest lasting prosumer digital camera we have tested. Four and a half hours on a single charge, very impressive.