When you build the follow-up to a hot camera, how do you turn up the heat? When Nikon shipped the D200 a couple of years ago, its combination of speed and photo quality blew away the limited competition, and provided a powerful, relatively inexpensive alternative to Nikon's then top-of-the-line D2X. The D300 faces a far more crowded field. Not only does it take on its venerable and now lower-priced predecessor, but also a cluster of far-from-shabby dSLRs just at or below its price: the Canon EOS 40D, the Sony Alpha DSLR-A700, the Olympus E-3, and the Pentax K20D.

Nikon's offering a body-only box of the D300 as well as two kits: one with a DX 18mm-135mm f/3.5-5.6G ED AF lens (27mm-202.5mm equivalent with the camera's 1.5x crop factor) and one with a DX 18-200mm f/3.5-5.6G ED VR lens (27mm-300mm equivalent). I tested the latter kit, and also used the camera with two non-DX lenses: a preproduction version of the 14-24mm 2.8G ED and the 24-70mm f/2.8G ED IF.

For the most part, Nikon sticks with the tried-and-true body design and interface of the D200, with its intelligently laid out controls. The dust- and weatherproof body weighs a hair over 2 pounds, and feels as solid as a little tank. The viewfinder is bigger and brighter, with 100 percent coverage. There are a few behaviors I'm not fond of, like the hard to manipulate metering dial (discussed in my more-detailed analysis of the design) and occasionally problematic AF-mode navigation (discussed below), but find the camera's operation comfortable and fluid. Nikon carries over the ultraflexible user-settings menus, which consists of two banks--shooting settings and custom settings--with four nameable slots each.

Though the DX-format (23.6x15.8 mm), 12-megapixel CMOS sensor is new, the D300 otherwise retains the raft of features that made the D200 so powerful, plus some high-profile enhancements. Most notably, the D300 increases to 51 AF points with 15 cross-type sensors, which contributes to the camera's new 3D-tracking 51-point Dynamic Area AF mode, and replaces the Group Dynamic AF of its predecessor. Essentially, the D300's 1,005-point 3D color matrix meter does double duty, feeding a low-resolution digitized version of the scene to the new Multi-Cam 3500DX AF module for tracking analysis. (You can see an interesting video simulation of it on YouTube.)

Based on the description (and the suggested use in the manual), the 3D tracking mode seems like an optimal solution for shooting well-defined subjects--those with strong color contrast relative to the background and which occupy a large percentage of the scene--that remain within the frame. And in shoots at a local dog run, it worked best for portrait-type situations, where it tracked the dogs' wildly moving heads while they themselves remained relatively stationary within the frame. However, for shots where the subject moves too quickly to keep in the viewfinder--as happens with most of the other dog-run shots--Nikon suggests using the 51-point dynamic AF without the 3D tracking. That works relatively well. (You can also choose 21-point or nine-point without 3D.) However, I miss the AF-group visual feedback provided by the D200. (Editor's note: The original version of this review had an erroneous complaint about not being able to assign these to custom buttons; in fact, you can assign swapping between the different multipoint AF modes to a custom button and dial combination.)

Like the 40D, the D300's Live View mode supports autofocus, but the D300 uses the typical too-many-mirror-flips implementation that makes it far less useful than it could be. There's actually a flow chart in the manual explaining the series of steps it takes to shoot in Live View--with a tripod it can use contrast AF, which doesn't require the constant mirror flippage. It is neither complicated, nor the shooting experience one should expect.

Like Canon, Nikon has a lot invested in lens-based optical-image stabilization technology, so the D300 lacks the in-body sensor-shift stabilization that Sony, Pentax, Olympus, and Panasonic offer. That's not a big deal if you already have an investment in Nikon's VR lenses or don't really use/care about stabilization. But if you do care about it and making your first dSLR purchase, or contemplating shifting from another brand, then don't discount its importance; the fact that the two kits require a choice between VR and non-VR lenses foreshadows future lens choices you'll have to make.