Nikon today introduced two digital SLRs: The D3000, which is aimed at mainstream and novice users, and the D300s, aimed squarely at professional and enthusiast shooters.

The US$600 D3000 continues Nikon's new model nomenclature, begun with the recent D5000. The D3000 replaces Nikon's D40x which has had an impressive run and remains a leading budget SLR choice. The camera kit ships with the AF-S Nikkor 18-55mm f/3.5-5.6G VR lens with image stabilization.

The D3000 marks a major refresh. This model is about the same size as the D40, but it bumps the megapixel count from 6 megapixels to 10MP. It has a wider range of ISO settings, now 100 to 1600; a larger LCD screen (3-inches, to the D40-generations 2.5-inches); an 11-point autofocus system (same as in the D90 and D5000); and a 3-frames-per-second burst mode (up from 2.5-frames-per-second).

The redesigned menu makes it easy to maneuver through the menu options, and to understand settings and get assistance as you go along. And the camera boasts a slew of scene modes and in-camera editing features, including scene recognition, Active D-Lighting, face detection, and a retouch menu (with funky effect modes like miniature and outline modes).

The midrange, $1800 (body only) D300s succeeds Nikon's D300, a versatile and flexible model introduced two years ago. The D300s shares many of the characteristics of its predecessor: Both have a 12.3-megapixel CMOS sensor and 51-point autofocus system. The shape and size are similar, too.

However, the D300s boasts a number of useful upgrades that its intended audience should appreciate. The camera has a faster Expeed processor than the D300 used; this new processor enables faster burst-mode (7 frames per second in continuous shooting mode) and the cameras HD movie feature. The first pro-level DSLR from Nikon to include video recording, the D300s can capture 720p high-definition video at 24fps, offers autofocus in movie mode (using the camera's contrast-detection autofocus system), and includes a stereo input to add an external microphone.

The D300s now has 11 additional custom settings, and three additional retouch functions. A nifty addition: Active D-Lighting, which provides real-time image adjustments, supports five-frame bracketing, so you can easily capture different exposures and see how they will look, automatically.

Another welcome new feature: The addition of dual memory card slots. In an interesting twist, Nikon provides both CompactFlash and SD Card slots (previously, the D300 only had a CompactFlash Card slot), and the slots are designed with similar features as on the D3 (for example, the ability to transfer images from one to another). Even niftier: You can set the camera to save still images to one card, and movies to another--a huge convenience for sorting and organizing content as you capture it.

Both cameras will ship in late August 2009.