Nikon D90

Focus
Auto Focus (10.00)
When shooting with the optical viewfinder (versus Live View), the D90 employs an 11-point focus system (with one cross-type sensor). Three auto focus modes are available. Single-servo auto focus locks focus setting when the shutter is depressed halfway. Continuous-servo auto focus continues to adjust the focus setting as long as the shutter button is halfway depressed, making it suitable for following moving subjects. The default mode, Auto select,  lets the camera chooses between single-servo and continuous-servo modes automatically based on subject movement.

Four different focus point selection modes are provided. In the default auto-area mode, the camera detects the subject and chooses a focus point, with priority given to recognized human subjects. 3D tracking lets the user choose one of the 11 focus points, then follows the subject within the frame as long as the shutter button is depressed. In dynamic area mode the user chooses a focus point, but the camera factors in data from adjacent points if the subject moves. Single-point auto focus, predictably enough, maintains focus on a single user-selected point.

And if all that flexibility isn't enough, you can set the center focus point behavior, toggling between normal zone, which maintains a narrow central focus and works well with stationary subjects, and wide zone, better for handling moving subjects at the center of the viewfinder. An effective auto focus assist lamp, with a claimed range up to 9 feet 10 inches, is positioned between the shutter release and the viewfinder hump.

More important than the panoply of settings, of course, is actual performance. We found the camera’s auto focus performance was reasonably fast, but not as impressive as higher-end rigs. Of course, the lens is a major factor in determining auto focus performance, and our experimentation was limited to the 18-105mm VR model that’s being promoted as a match to the D90.

As discussed in the Live View section above, auto focus in this mode uses contrast detection technology, and was distinctly underwhelming when it came to focus speed – so much so that we consider it inappropriate for photography of moving subjects.

Manual Focus (8.50)
Depending on the lens being used, manual focus is enabled by flipping a switch on the lens barrel or the AF/M lever on the camera itself. In either case, the in-focus indicator in the viewfinder will stop blinking when sharp focus is achieved. When shooting in Live View mode, pressing the zoom-in button will magnify the on-screen image, making it easier to see whether or not the image is sharp.

ISO (8.50)
As with other Nikon SLRs, the D90 has a range of official ISO settings plus several if-you’re-feeling-lucky settings, not reliable enough for the engineers to fully endorse, but not bad enough to keep the marketing guys from embracing them. The official settings have ISO numbers, the others are indicated by Lo and Hi designations. For the D90, the numbered ISOs range from 200-3200 in 1/3 EV increments. If you’re dead set on hitting a lower ISO, the camera offers L 0.3 (roughly equivalent to ISO 160), L 0.7 (ISO 125) and L 1.0 (ISO 100). Pushing for higher sensitivity in dark environments, H 0.3 is roughly ISO 4000, H 0.7 is ISO 5000 and the top setting, H 1.0 is about ISO 6400. Of course, pushing into this extended ISO range territory will boost image noise.

One oddity about the ISO setting system involved Auto ISO, a handy capability that's limited here to the full Auto mode. There is a secondary auto ISO system that will change a setting the user has entered if it absolutely prevents an image from being taken, but that's hardly a substitute.

White Balance (8.50)
In addition to the default Auto white balance setting, the D90 offers a generous selection of white balance presets, including incandescent light, direct sunlight, flash, cloudy, shade and seven different flavors of fluorescents. Savvy photographers can also enter the color temperature indirectly in degrees Kelvin, or take a manual white balance reading by shooting a neutral gray or white surface. These direct measurement results can be stored in four memory slots, so they can be re-used if you return to the same shooting environment. It’s also possible to copy a white balance value from an existing photo stored on a memory card.

The D90 provides a generous number of
presets plus custom controls.

Exposure (10.50)
In addition to two full-auto exposure modes (with and without flash), the D90 offers program, shutter-priority, aperture-priority and full manual exposure modes. In Program mode, turning the main command dial enables "flexible program" mode, which adjusts the aperture to larger or smaller settings (larger numbers = greater depth in focus), with the shutter speed shifting in tandem so the overall exposure remains the unchanged.

Exposure compensation is available in a plus or minus 5 stop range, wider than we ordinarily encounter. The exposure compensation button, which must be held down while turning the main command dial to enter settings, is inconveniently positioned just behind the shutter release, requiring you take your index finger away from the trigger and contort your right hand uncomfortably to make the adjustment.

Exposure bracketing is also available, up to three frames, with increments from 0.3 EV to 2.0 EV.

Active D-Lighting is Nikon’s dynamic range manipulation system, which reads the image and boosts gain in the shadowed areas while suppressing blown-out highlight in excessively bright regions. The D90 offers the Auto setting for this feature, recently introduced in the D700, which lets the camera set the level of D-Lighting effect applied. If you prefer, you can set Active D-Lighting to one of four levels (Extra high, High, Normal, Low). The same fundamental technology is also available after the fact, in the D-Lighting feature on the Retouch menu, though the range of enhancement offered as a retouch effect is more limited.

Metering (8.75)
The D90 relies on a 420-segment RGB sensor for exposure metering. 3D color matrix II is the default for auto and scene modes, reading a wide area of the frame and setting exposure to achieve a pleasing overall balance. Center-weighted metering reads the same large area but favors the center area when coming up with an exposure setting. Finally, spot metering looks only at the middle 2.5% of the frame.

Shutter Speed (10.00)
Available shutter speeds range from a snappy 1/4000 second to 30 seconds, plus a Bulb setting (only in manual mode) for unlimited exposure time.

Aperture
Available aperture settings are, of course, dependent on the lens being used. The D90 does include a depth of field preview button, located at the bottom left of the lens mount, that stops down the lens to the shooting aperture for an accurate view of the areas that will be in focus in a photo taken at the current setting. This is a valuable feature frequently omitted from more bargain-priced SLRs, one good reasons for paying a little extra for a more full-featured camera, in our opinion.