Although it lacks the staggering number of megapixels you'll find on the newer Nikon D3200 (*Est. $650 with kit lens), the D3100 takes photos that are pretty comparable in tests and it'll save you about $150. Aside from resolution and video features, these two cameras are otherwise virtually identical and image quality is much the same. So if you're on a tight budget, reviews suggest going with the D3100.
Helps beginners get the shot. Nikon's cheapest digital single-lens reflex (DSLR) camera is nearly indistinguishable from the step-up D3200 except for a few features. Testers find both cameras comfortable to grip and lightweight to carry, with easy-to-find buttons and easy-to-navigate menus. The D3100's LCD screen isn't as high-resolution as the D3200's, but reviewers don't complain. Both cameras offer Live View so you can frame your shot on the screen, but experts say autofocus works sluggishly this way, so it's better to look through the optical viewfinder.
Beginners can simply set the D3100 to Auto and let the camera do the work, or you can switch to Guide Mode and learn from the camera as you shoot. For example, if you select "Freeze motion (people)," the D3100 explains in text on the LCD screen that you should use a faster shutter speed. Alongside, a photo of a boy kicking a soccer ball shows how his leg and the ball get less blurry as you ramp up the shutter speed. In short, it "does a good job of helping novices get the shot, and learn how they did it," Imaging-Resource.com says.
The step-up D3200's guide mode is cut from the same cloth, but comes with more text explanations, illustration photos and lessons like "capture reds in sunsets."
Decently quick, with very good photo quality. The Nikon D3100 performs almost just like the pricier D3200, except for two things. It has fewer megapixels on its compact sensor -- 14.2 versus the D3200's sky-high 24.2 -- and it shoots a slower 3 frames per second (fps) compared to the D3200's 4 fps.
Theoretically, the D3200's faster shooting speed would make it better for photographing things like kids' sports, and critics say it's a pleasure to use in those situations. But nobody complains about the D3100's speed, either. "We suspect it will keep the vast majority of users perfectly happy," say testers at DPReview.com.
Also theoretically, the super-high resolution found on the D3200 would capture loads more detail than the D3100. When reviewers blow up the D3200's images and scrutinize them with a magnifying glass, they do notice finer details like thread patterns in fabrics that the D3100 can't capture in Imaging-Resource.com's test. But there are two downsides to more megapixels: grainier, "noisier" images in dim light and huge high-res photo files. The D3100 actually delivers better dim-light crispness and contrast in the same test, so it's really a wash, and its photos won't gobble so much space on your computer.
As for video, the D3100 lacks some movie features, but it does shoot full 1,080p HD video and can continuously autofocus while doing so. Its main rival at this price, the Canon EOS Rebel T3 (*Est. $495 with kit lens), tops out at 720p with no continuous autofocus. Keep in mind, however, that experts say no DSLR has proven to be a great tool for shooting video. Their continuous autofocus tends to be slow and loud -- so loud that you'll hear it on your movie -- and the Nikon D3100 is no exception.
Its battery is rated for 550 shots on a single charge, about the same as the D3200 but less than the 800-shot Canon EOS Rebel T3.
Plastic body feels solid. Body-wise, the Nikon D3100 and D3200 are much the same. They're the same small size and weigh just 1 pound, and are both made largely from plastic, but experts say they still feel solid.
"The body is composite and seems well built with materials, fit and finish appropriate for the price point," says Jim Keenan at DigitalCameraReview.com. The rubberized grip and thumb rest "promote a more secure feel," he says. Zoltan Arva-Toth at PhotographyBlog.com calls that rubber coating "surprisingly classy," and says it helps the D3100 exude "a degree of quality you might not expect at this price point."
"Surprisingly well-featured," but it does omit a few. For the Nikon D3100's rock-bottom price, you'll have to forgo some features. There's no external microphone jack for recording movies and the built-in mic isn't great, you won't get manual movie controls like aperture and mic level, and there's no wireless remote although you can add a wired remote. All of these things come on the step-up Nikon D3200.
Oddly, though, both Nikons lack standard exposure bracketing, where the camera takes three shots instead of one -- one normal, one at a slightly higher exposure and one slightly lower -- just in case the normal exposure wasn't quite right. The Canon EOS Rebel T3 has this feature. Even so, PhotographyBlog.com calls the D3100 "a surprisingly well-featured and complete package for an entry-level digital SLR camera."
Review Credibility: Very Good With HD video and Live View, the Nikon D3100 wins DPReview.com's Silver Award. Testers say it's "an excellent beginners camera" that newbies can grow with, but so are the new, cheaper, mirrorless cameras on the market.
Review: Nikon D3100 Review, Andy Westlake and Richard Butler, December 2010
Review Credibility: Very Good For point-and-shooters who want to upgrade to a more serious camera, the Nikon D3100 is a top pick at this reputable website. Experts here also thoroughly evaluate and recommend the newer D3200, but the cheaper D3100 remains on their list of best buys.
Review: Nikon D3100, Mike Tomkins, Shawn Barnett and Zig Weidelich, Dec. 13, 2010
Review Credibility: Very Good The Nikon D3100 gets a Highly Recommended tag here. The camera delivers outstanding images for its price, with higher resolution and better low-light performance than its predecessor, the D3000. However, Arva-Toth says the Live View and movie mode could use improvement. This website now prefers the newer Nikon D3200.
Review: Nikon D3100 Review, Zoltan Arva-Toth, Nov. 29, 2010
Review Credibility: Good With good still-image quality and a decent kit lens for the price, the Nikon D3100 scores 4 stars out of 5 here. Keenan finds some flaws, mostly with video mode.
Review: Nikon D3100 Review, Jim Keenan, Feb. 17, 2011
5. Ken Rockwell
Review Credibility: Good Photographer Rockwell bluntly advises shoppers to get the cheaper Nikon D3100 instead of the new D3200. "It's the same thing, and sells for less," he writes. "Resolution means nothing between these two cameras." Links lead to full reviews.
Review: Recommended Cameras, Ken Rockwell, October 2012
Review Credibility: Good The Nikon D3100 earns high ratings from more than 440 owners here. Although criticisms are posted, about 75 percent of users give the camera a perfect 5 stars.
Review: Nikon D3100 14.2MP Digital SLR Camera, Contributors to Amazon.com, As of November 2012