Trends Camera Nikon D3100

The 14.2-megapixel Nikon D3100 is a great entry-level digital SLR, and at $699.95 (list, with 18-55mm lens) it's the least-expensive D-SLR to capture 1080p video. It also includes a feature no other D-SLR has, continuous autofocus during video recording, which makes the D3100 feel like a camcorder while it's shooting. The camera can detect faces, lock on, and adjust the focus automatically to make video capture even easier. The only problem is that the lens isn't silent, so every time it refocuses you'll hear it. The Sony Alpha55 SLT-A55VL has faster autofocus, and the Sony NEX-3 and the Panasonic Lumix GH1 can focus silently, but if you want continuous autofocus in a true D-SLR, plus a true optical viewfinder, the Nikon D3100 is your only choice-but it's a good one.

Specifications
Type
D-SLR
Megapixels
14.2 MP
Media Format
Secure Digital High Capacity, Secure Digital Extended Capacity
35-mm Equivalent (Wide)
18
35-mm Equivalent (Telephoto)
55
Optical Zoom
3 x
LCD size
3 inches
Wireless Connectivity
No
HD Video Capture
Yes

Design and User Interface
At 3.75 by 4.75 by 2.5 inches (HWD), and 1.09 pounds (1.69 pounds with its included 18-55mm lens), the body of the Nikon D3100 is small and light for a D-SLR, but it still dwarfs a pocket point-and-shoot or compact-interchangeable-lens camera like the Sony NEX-3. Controls are standard—all the usual suspects are there (Mode Dial, Scroll Wheel, Directional Pad), and little else.

The 3-inch LCD the back of the D3100 offers a nice big view of your image, and large text so menus are easy to navigate. It's not very a sharp screen, however, like the one you get on the higher-end Nikon D300s whose LCD packs in 920K dots compared with the D3100's 230K. 230,000 dots is typical for an entry-level camera, but the D3100's screen actually makes images appear softer than they actually are-I'd like to see a sharper LCD on a D-SLR. The D3100 does have an optical viewfinder, however, so you're not limited to the LCD for framing shots.

Nikon's user interface is simple and straightforward across all models, and it makes the D3100 easy to use. Since the D3100 is aimed at novice photographers, Nikon also includes a Guide mode, which offers up shooting tips and instructions. It's useful if you're looking to learn, it can teach you, for example, how to capture moving subjects, soften backgrounds, or take night portraits. The Guide mode is easily accessible via the top shooting dial, and is just as easily ignored by an advanced shooter.

Still-Image Performance
When using the optical viewfinder for shooting, the D3100 is lightning fast. It starts up and shoots in an average of 1.35 seconds, and then delivers 3 frames per second in continuous shooting mode. Autofocus speed in Live View mode (when you use the LCD to frame your shots), and during video recording are also impressive. The Canon EOS 7D, which costs twice as much, can autofocus in Live View in an average of 3.67 seconds, while the D3100 takes just 2.41 seconds. But both get crushed by the Sony NEX-3, which can autofocus and snap in just .9 seconds. The Sony Alpha55 is even faster than that—thanks to its translucent mirror technology, it can autofocus and shoot in Live View mode as fast as a true D-SLR can with its optical viewfinder.

In the PC Labs we use the Imatest suite to measure objective image quality factors. Many of the Nikon D-SLRs I've tested don't produce the sharpest images, but they're still crisp, and the cameras typically do a fantastic job in low light. The D3100 is no exception—after analyzing 50 spots through a frame captured at ISO 100, the D3100 averaged a center-weighted 1,623 lines per picture height-1,781 in the center regions, 1,512 part way to the corners, and 1,320 in the corner regions (more lines means a sharper image). By comparison, the Nikon D5000 averaged 1,778 lines, and the Editors' Choice Canon EOS Rebel T2i averaged a razor-sharp 2,102 lines. In terms of image noise, the Nikon D3100 can go past ISO 3200 to ISO 6400 and keep noise under the 1.5-percent threshold for useable images. This means the D3100 is well-suited for shooting in low light environments without flash.

Video Performance
Like with most D-SLRs, video quality from the D3100 is better than what you'd get from a consumer-grade or pocket HD camcorder—like the Cisco Flip Ultra HD 8GB. This is because D-SLRs have much larger sensors. With the D3100, HD video can be captured in 720p at 24 or 30 frames per second or 1080p at 24 frames per second. (The D3100 is the least expensive D-SLR to offer that 1080p capture.) You can adjust the shutter speed and aperture to control the depth of field in video footage as you would with still shots.

The D3100 is the first D-SLR to offer continuous autofocus while recording video, that means it can keep moving subjects in focus while shooting, much like a dedicated camcorder. The feature works well, but there are some shortcomings. The D3100 can focus a little more quickly than most other cameras, but it's not the blazing-fast speed you'd get from the Sony Alpha55, which can autofocus in a fraction of a second.

And the lens is not silent. Any time you refocus you'll hear a loud grinding noise. This issue is common to D-SLRs, but you can usually get around it by attaching an external microphone, but not with the D3100, there's no microphone input. Mirrorless competitors like the Sony NEX-3, the Panasonic Lumix GH1, and its upcoming successor the Panasonic Lumix GH2 use lenses that offer silent refocusing.

Connecting the D3100 to a computer is simple, since the camera is armed with a standard mini-USB port. The mini-HDMI port lets you play back your video and still images on your HDTV. The D3100 is powered by a rechargeable lithium-ion battery and writes to SDHC/SDXC cards.

At $700 with lens, the Nikon D3100 is easy to recommend, it offers great image quality, a helpful Guide Mode for newbies, and continuous autofocus for those who want a true D-SLR with simple video recording. Despite not being able to offer continuous autofocus, the Canon EOS Rebel T2i remains our Editor's Choice budget D-SLR since it offers top-notch image quality, a much better LCD, and a wider choice of video resolutions and frame rates. If you're looking for a camera that offers something closer to a true camcorder experience, the Sony Alpha55, the mirror-less Sony NEX-3, and the Panasonic Lumix GH1 are worth checking out.