At the D300's core is a 12.3-megapixel CMOS sensor. Although it's not quite a full frame chip, it's large enough -- and Nikon confident enough in its noise reduction systems -- to offer sensitivities ranging from ISO 200 to 3,200, with additional Low (down to ISO 100) and High (up to 6,400) settings if you want to push it. Like most new SLRs, it has a cleaning system to prevent dust sticking to the sensor. Set this to activate on shut-down to avoid it slowing any snapshots.
The EXPEED processing engine on board allows burst shooting up to around 6 frames per second. That's as good as any camera in the price range and, together with a top shutter speed of 1/8000-second, should be sufficient for any but the most frantic sports photographer.
Naturally, the D300 can shoot raw images as well as JPEGs. Nikon's NEF format raw files can be saved as either 12-bit or larger 14-bit files, which hold increased colour depth information. Be warned, though -- top quality uncompressed files can be as large as 32MB in size. You'll also sacrifice speed, with a maximum continuous shooting speed of just 2.5fps.
To enumerate every manual feature on board the D300 would take longer than downloading a multi-gigabyte card full of its raw files, but there are a few that are worth singling out. While you don't get the simple scene modes found on cheaper cameras, the D300 does have fully customisable Picture Controls to tinker with contrast, colour and sharpness. There's also Active D-Lighting, a system that analyses scenes when you shoot and almost instantly adjusts them to preserve details in both highlights and shadows.
Another impressive innovation is 3D tracking autofocus. Activate this and the D300 will lock on to subjects in the focus frame and keep them pin-sharp, however erratically they're moving. All you have to do is hold the subject within the generous 51-point autofocus zone and keep your finger on the shutter.
Of course, you can also adjust white balance, exposure, focus zones and much more besides, using themed areas within the shooting menu. That programmable Function button is worth using too, if only to save time delving into deep menus for settings you might adjust once or twice a day -- it's set for bracketing by default.
The D300 ships with Nikon Transfer software that's fairly basic apart from its ability to automatically save files in two locations; one as a back up. You also get Nikon ViewNX, a photo viewer that lets you apply simple exposure, white balance and Picture Control tweaks to your NEF raw files. If you want a more sophisticated raw file editor, Nikon's Capture NX (£85) is well worth the investment.
Despite its size, the D300 is one speedy camera. Power up is virtually instantaneous and there's no discernible shutter lag. Autofocusing is quick but not the absolute fastest we've seen on an SLR -- that honour probably rests with Olympus's compact E-3 camera, launched last year. Again, this is unlikely to be an issue unless you're really chasing micro-seconds.
The Nikon D300 ships body only, and it would be crazy not to marry it to some decent optics. We tested it with the AF-S 17-55mm f/2.8G lens, which has the DX mount designed to work with the D300's size of sensor.