Timings & File Sizes

The Coolpix 3100's slowest function is power up, which was a surprise because the lens takes around 1.5 seconds to extend, the remaining time appears to be taken by the camera's CPU. This caused the camera's Off to Shot Taken time to suffer. Auto focus was fast in good light (at both wide angle and telephoto) but quite slow with a tendency to 'hunt' in low light, remember the 3100 doesn't have an AF assist lamp. Shot to shot time was good but the camera's buffer is just too small as it stopped us from taking more than two 3mp High JPEG shots in a row. Playback and play zoom were both fast. Camera menu operation felt speedy enough.

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 2048 x 1536 High JPEG image (approx. 900 KB per image). The media used for these tests was a 256 MB SanDisk Ultra CF card.

Action Details Time, seconds
Power: Off to Record Lens extension 3.5
Power: Record to Off Lens extended 2.5
Mode: Record to Play *1 Image displayed 0.8
Mode: Play to Record   1.3
Play: Magnify To 6x magnification 2.5
Play: Thumbnail view 2x2 index, 4 images 0.5

Action Details Time, seconds
Zoom from Wide to Tele Full zoom from 38 mm to 115 mm (3 x) 1.5
Auto Focus LAG Wide angle 0.7 - 1.6
Auto Focus LAG Telephoto 0.8 - 2.2
Shutter Release LAG Using Viewfinder <0.1
Shutter Release LAG Using LCD Monitor 0.1
Total LAG Wide angle 0.8
Total LAG Telephoto 1.3
Off to Shot Taken Wide angle 4.3
Shot to Shot Wide angle 1.7

*1 This is a 'rough image' displayed from a thumbnail stored in the image file header, this is replaced by a more detailed image approximately 1.4 seconds later (once the camera has loaded the full image data from the CF card).

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 mode

The Coolpix 3100 has only one continuous shooting drive mode as well as a '16 on a frame' mode seen on previous Coolpix digital cameras. In continuous drives mode the camera will shoot continuously while the shutter release button is held or until the internal buffer is full.

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 256 MB SanDisk Ultra CF card.

Image Type Frames per sec Max no. of frames *1

Wait before
next shot

2048 x 1536 High JPEG 1.07 fps 3 3.4 secs
2048 x 1536 Normal JPEG 1.83 fps 5 4.2 secs
1600 x 1200 Normal JPEG 1.45 fps 7 3.2 secs
1024 x 768 Normal JPEG 1.55 fps 17 2.7 secs

*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").

Shooting continuously with the Coolpix 3100 you can hear the camera shooting rate increase after the second frame and slow slightly before the last. This explains the inconsistent frames per second measurement, in 3mp High mode because there are only three frames the overall speed is dragged down by the slow first to second frame time. In 3mp Normal mode the camera gets into its stride nicely and then stops suddenly, the rest are a closer measurement of the true rate. To be honest these results aren't great, most other cameras at this price point shoot at a similar rate but are able to buffer more images.

File Write / Display and Sizes

Timings shown below are the time taken for the camera to process and "flush" the image out to the CF card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator 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 256 MB SanDisk Ultra CF card.

Image Type Time to write

Time to display
File size *2
Images on a *3
256 MB CF
2048 x 1536 High JPEG 2.8 1.3 900 KB 161
2048 x 1536 Normal JPEG 2.5 1.1 600 KB 316
1600 x 1200 Normal JPEG 2.4 0.9 380 KB 504
1024 x 768 Normal JPEG 2.2 0.8 170 KB >999

*1 The 3100 displays a "rough image" almost immediately after moving to another image in play mode, the time here is the time for the camera to load the full resolution image which it then applies over the rough image. You can't magnify an image until the full resolution image has been loaded.
*2 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.
*3 Camera estimation.

Average performance for a camera at this level, the time to write doesn't affect taking the next shot unless the buffer is full (two or three 3mp images). Playback is virtually instant, there is only a slightly delay for the camera to load the full resolution image.

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 (38 mm equiv.) F2.8 1.0 EV (5.0 Lux, 0.46 foot-candle)
Telephoto (115 mm equiv.) F4.9 2.5 EV (14.1 Lux, 1.31 foot-candle)

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

For a camera without an AF assist lamp the Coolpix 3100 does well at wide angle and slightly less so at telephoto. All things considered this performance is slightly better than we would expect at this price level (and without an AF assist lamp).

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 Coolpix 3100 lasted for approximately one hour and forty five minutes, which was a match for Minolta's DiMAGE F100 and the Olympus C-40Z both which were also powered by two AA NiMH batteries. I personally would like to have seen the 3100 lasting at least as long as HP's 812 (two hours twenty minutes). This performance means that you would almost definitely have to carry a spare set of batteries (although not much of a hardship as it only takes two).