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Video

Probably the most headline-grabbing feature of the D90 is its ability to capture video (the first DSLR to offer such a feature). And rather than faffing around with the VGA (640 x 480) output that has been a staple of compact cameras for many years, Nikon gone straight for 720p HD (1280 x 720) that is just starting to appear on small-sensor cameras. The movies are recorded at a distinctly cinematic 24fps - its a common film movie camera frame rate (perhaps it's felt that the digital camera industry needs more legacy standards that don't necessarily work at their best with contemporary digital technologies - LCD and Plasma screens in this instance).

Sizes • 1280 x 720 (24 fps)
640 x 424 (24 fps)
320 x 216 (24 fps)
Audio 16-bit Mono, 11 kHz (Internal Mic only)
Format AVI (Motion JPEG)
File size ~1.7 MB/sec (HD)
Running time 5 min in HD, 20 min all other modes

The results are impressive when compared to the output from compact cameras - though wouldn't stand up to the kinds of scrutiny we apply to still images. However, because the sensor (and its readout method), probably wasn't designed specifically with movies in mind, there are some interesting effects that can be induced. The readout of the sensor means movies are created with a rolling shutter (horizontal lines of the image are scanned, one after another, rather than the whole scene being grabbed in one go). The upshot is that verticals can be skewed if the camera (or the subject) moves too fast - the top of the image has been recorded earlier than the bottom, so moving vertical lines can be rendered as a diagonals.

However, it's hard to escape the impression that this is a first-generation implementation. Aperture (and hence depth-of-field) must be selected before entering Live view mode, so the video adjusts its exposure using variable gain, rather than by adjusting shutter speed or aperture. The automatic exposure can result in rather 'stepped' exposure changes - the aperture is locked so the problem seems to stem from amplifier stepping. Color rendition is not as convincing as in stills recording, with the red channel appearing to clip in our bus sample. Autofocus is also only available prior to recording, using the less-than-spritely contrast-detect mode, so once the 'rec' dot appears, you'll be left having to focus manually.

The resultant movies are good by 'stills camera' standards, caturing a lot of detail and playing smoothly. The large sensor means the performance in low light is very good, though we do see some slight banding in very dark situations.

The sound recording has a fairly low sampling rate (11 kHz, Mono, compared to the 48 kHz, Stereo sound recorded by most dedicated video cameras), collected through and internal microphone (with no option for an external one), that tends mainly to record the sound of the camera operator.

On this basis, the D90 probably isn't a camera you'd buy for its video capability (it's almost as if the camera has been primarily designed for a different purpose), but it's an interesting extra feature to have and it's been included in a way that is both accessible and unobtrusive so can only be seen as a bonus. And one that we're sure we'll see some incredible results from, once placed in tenacious, creative hands.

Sample video

1280 x 720, 24 fps. AVI (motion JPEG) file. 5 sec. 14.4 MB

Sample video (with moderately fast motion)

1280 x 720, 24 fps. AVI (motion JPEG) file. 2 sec. 5.7 MB

Sample video showing shallow depth-of-field

1280 x 720, 24 fps. AVI (motion JPEG) file. 5 sec. 8.8 MB

Sample video emphasizing rolling-shutter skew

1280 x 720, 24 fps. AVI (motion JPEG) file. 2 sec. 5.6 MB
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