Body & Design
At first glance the D3100 looks a lot like its predecessor, but the changes are more significant than the small numerical change would suggest. The higher resolution sensor brings with it several other enhancements such as live view and video capability. These additions, of course, require subtle changes to the camera body to accommodate them. On the back there's a sprung lever to enter live view, which surrounds a small red-dotted button that initiates movie recording; the previously-combined '+' and 'i' functions also now each get their own button (as both functions need to be available in live view). On the top plate, the new drive mode switch makes for a very welcome addition.
In addition to these buttons and switches the D3100 has also gained a proper rubber grip, rather than the rubberized coating that featured on the D3000 - a small change but a big improvement to handling. Small grilles on the front and back conceal the microphone that's used during movie recording and the speaker that provides sound during playback respectively. Finally the D3100 gains two connectors under the enlarged rubber door on its left side, namely HDMI for movie playback and a combined GPS / remote release socket, but loses the D3000's IR remote receiver in exchange.
Side by side
The D3100 is a similar size to its obvious competitors, the Canon EOS 1000D and Sony A290. Being the newest camera in this group it's no surprise that it offers the highest specification, and its Full HD movie recording (albeit at 24 fps) and 14.2MP sensor makes it look pretty impressive. Like the other two cameras here, the Nikon offers a decent degree of external control and, as a result, requires very little menu diving.
In your hand
Thanks to its lineage the D3100 remains one of the most pleasant to hold cameras in its class. It may be small but it's very comfortable to use. It's almost impossible to pick up without your hand falling into a sensible position with the key controls at your fingertips. The layout and positioning of the buttons is some of the best we've come across and their function has on the whole been carefully thought-out too. Our one quibble would be the positioning of the Fn button (which many users, we suspect, will use to control ISO) on the side of the camera, while the the far-less-useful 'info' button occupies prime real estate beside the shutter release.
Viewfinder specs and view
The D3100 has a very typical viewfinder specification for its class of camera. It offers 0.8x magnification and a 95% field of view, which is pretty standard.
One figure hidden away in every SLR's spec is the size of the viewfinder (often in a format that makes comparison between competing models impossible). The size of the viewfinder is a key factor in the usability of an SLR - the bigger it is, the easier it is to frame and focus your shots, and the more enjoyable and involving process it is.
Because of the way viewfinders are measured (using a fixed lens, rather than a lens of equivalent magnification), you also need to take the sensor size into account, so the numbers in the diagram below are the manufacturer's specified magnifications divided by the respective 'crop factors'.
|The D3100's viewfinder is almost precisely the same size as those offered by its immediate peers. It loses a bit of ground to the A290 but is a fraction larger than that of the EOS 1000D.|
Most cameras at this level crop the frame slightly when you look through the viewfinder - in other words you get slightly more in the final picture than you see through the viewfinder. In common with most of its competitors the D3100 only shows 95% (vertically and horizontally) of the frame.
|Nikon D3100: 95% viewfinder.|