Serious upgrades in the still and video department make this a serious entry-level contender.
Apparently, when Nikon decided to add video capture functionality to its D3000 follow-up, they weren't just kidding around. Not only have they made it the first Nikon DSLR to capture full 1080p (1920 x 1080) footage, but they also made it the "world's first" DSLR with full-time auto focus in Live View and D-Movie modes. It can even capture the 24p stuff that cinema-types crave.
Non-video shooters will also be glad to know that there are plenty of photographic enhancements as well. The maximum native ISO has been bumped from 1600 to 3200 (expandable to 12,800). They traded in the D3000's 10.1-megapixel CCD sensor for a 14.2-megapixel DX-format CMOS. And they have upgraded the image-processing engine to their new Expeed 2.
As a compliment, they have also kept around many of the features that worked well on the D3000. The D3100 has the same 11-point AF system, 3-inch LCD display and even the Guide Mode, which provides on-screen tips and tutorials for users still trying to master a range of photographic techniques. While it may not get much use from more experienced shooters, we're big fans of the system. Rather than pushing users into automated scene modes that hide the photographic process, they actually try to help shooters understand how to make great pictures.
When you take into consideration the beginner-friendly attitude with which Nikon has approached this camera, the video upgrades make total sense. Not only does it offer full-time AF (contrast-based) during video capture, but it can also lock focus on up to 35 human faces. Footage is captured in an H.264 codec (.mov) and can be edited in-camera. While many find in-camera editing of still images to be unnecessary (the D3100 does offer this), it proves to be advantageous in terms of video, as one is able to clip off extraneous footage before it makes its way to a computer or to an HDTV using the on-board HDMI-port.
Of course, as with any entry-level DSLR, the D3100 also offers a selection of traditional shooting modes, including the Scene Recognition System and the Auto Scene Selector found in many Coolpix cameras.
The D3100 is set to hit shelves beginning in mid-September for $699 when bundled with the 18-55mm f/3.5-5.6G VR. That's a full $200 cheaper than the kit version of Canon's Rebel T2i, which means the entry-level fight has just escalated even further.