Samsung NV7 OPS Review
The NV7 can capture movies at up to 640x480 pixels (VGA) at 30 fps. Movies are saved as AVI MPEG-4 files using the DiVX codec. This means they're small, but you do need to install the decoder on your PC to view them. This is supplied for Windows but Mac users need to find and download it themselves.
The DiVX movies are very small (it's a very efficient compression), and quality is okay, though nothing special (they're a bit soft and show strong compression artefacts). You can zoom whilst shooting, though this tends to cause the focus to fail briefly - and appears to be at the root of the sound drop-outs we experienced in many clips (such as the one at the bottom of this page). You can also, unusually, pause recording. There are some rudimentary in-camera movie editing controls.
|Whilst shooting movies the screen shows elapsed time and a pause button. There are options for movie size / frame rate and sound on/off. You can also use the AE compensation (+/-), white balance, focus and metering options in movie mode. Finally as mentioned above you can use the zoom when filming, but our experience was that this caused distracting focus hunting.|
|In playback mode you'll find controls for playing the movie clip, and options for saving single frames as JPEGs, plus very basic editing controls..|
|... these simply allow you to trim sections from the start and end of recorded clips.|
Sample movie clip
640x480 pixels @ 30fps
Shot using zoom (tele to wide)
Click on the thumbnail to view the movie (caution: large file!)
Optical image stabilization
The NV7 OPS (optical picture stabilization) is the first Samsung compact to feature a mechanical image stabilization system (using a CCD-shift system) - pretty much essential with such a long zoom on such a small body.
There are two modes: mode 1 is activated at the moment the shutter is released, whereas mode 2 is activated at the half-press point (which in theory means you get a stabilized preview, though we could hardly see the difference). There's no indication in any of Samsung's documentation what the benefits - if any - of one mode over the other are, or if there are particular situations either is better suited to. Our extensive testing would seem to indicate that mode 1 has a the edge, more often producing a significant stabilization than mode 2, which seems very hit an miss. You can actually hear the CCD moving in mode 2 (when the shutter is half-pressed), so we'd presume excessive use of this mode will also reduce even further the woeful battery life. In fact if the battery is low the OPS won't activate at all (nor will it come on if the sensor is too warm).
Although we've no definitive test for IS systems in real-world use, I feel confident in stating that the CCD-shift system used by the NV7 OPS is no match for the moving-lens stabilization offered by the likes of Canon and (especially) Panasonic - it is also far less effective at stabilizing the preview image, and can't be used in movie mode. This backs up our belief that CCD-shift simply can't compete with lens shift at the long end of the zoom. At the wide end the difference is less stark, and we found it perfectly possible to hand-hold shots as low as 1/10th sec fairly successfully (helped by the stabilizing effect of a relatively heavy camera to start with).
Whereas some of the lens-shift IS systems we've tried offer a reliable 3 stop advantage over shooting un stabilized (some producing acceptable results half the time at 4-5 stops), the NV7's system is only totally reliable at one or two stops, once you get to three or four (1/30th or 1/25th at full tele) the hit rate is very low indeed for mode 2, though mode 1 produces an acceptable result maybe 4 out of 10 times.
If you are working within reasonable expectations - down to say 1/60th sec at full zoom - the system is fairly reliable, just don't push it; as the examples below show neither mode can fully stabilize at 1/20th sec at full zoom - 270mm equiv. - (the Panasonic FZ7, for example, can do this).
|1/10th second, hand-held, 270 (equiv.)|
|IS off||IS on (mode 1)||IS on (mode 2)|
|1/20th second, hand-held, 270mm (equiv.)|
|IS off||IS on (mode 1)||IS on (mode 2)|
ASR (Advanced Shake Reduction)
The NV7 OPS - like most of its stable mates - features Samsung's unique ASR function, a DSP based anti-blur system that offers something slightly different to the usual massive ISO boost.
Although details are somewhat sketchy (Samsung's own documentation only gives the merest hint of what's going on) our experiences with ASR over the last couple of years, combined with what little information there is (including conversations with Samsung representatives) indicate that at the heart of ASR is a double exposure. The first, which uses a high shutter speed, captures what will become the 'detail' of the shot (luminance information), the second - taken at a longer shutter speed - is used to capture the color (chroma) then the two are combined with a little signal processing magic.
What's not clear is how much of an ISO boost is used for the first shot - for there most surely is one, though it seems that the second, color shot is always at ISO 200 (the exif data is only given for this second, longer shot, and it always appears to be ISO 200, and whatever shutter speed the light levels dictated).
The net result is often surprisingly successful - it's certainly a noticeably better system than cranking the ISO up to the max, but it is by no means perfect. For one thing the results are quite noisy (shooting at ISO 200 in non ASR mode is noisy enough, this is a little worse). It also produces unpredictable results in very low light (when the second, color exposure is so long the DSP can't work out quite which colors go where). And it doesn't deal well with subject movement (the first, fast exposure is fine, but the subject will blur during the second one). For the same reason you have to hold the camera very still during the brief period after you've taken the picture, when the screen says 'processing'. This can be quite a long time in low light - if you forget you'll not get very impressive results.
All in all Samsung must be applauded for at least looking into how to avoid the problems of camera shake, and for the typical 'point and shoot' consumer producing small prints ASR has some use, and will increase the 'hit rate' for shots taken in circumstances where the mechanical stabilization isn't up to the job. The quality's not great, but it's not that much worse than the camera's normal output (and you get better colors too).
|ASR off, ISO 200, 1/6 sec||ASR on, ISO 200, 1/6 sec|
|High Altitude Rocky Mountain Railroad by cjf2|
from On the Rails...
|Evening at the lake. by Murat ÜNSAL|