The thing that really sells the Nikon D5100 is its 921k-dot, 3-inch, vari-angle LCD screen. Because this is mounted on a side hinge, it's possible to turn it away from the camera and rotate it through any angle. This provision is particularly useful for video capture where a waist-level or high-up shooting position may be desired.
- Read our full Nikon D5100 review
It's worth noting that the D5100 was released before the more budget Nikon D3100. However, the latter release benefitted from live view improvements that translated into faster movie autofocusing. When the D5100 was released, these improvements hadn't been rolled out, so, as a benchmark, the D3100 is actually a more capable video shooting machine in terms of its autofocus ability.
The D5100 offers edge-to-edge focusing across the whole screen, and it's possible to move the AF-Area focus point anywhere, using the D-pad. In addition, there are Face-Priority AF and Subject Tracking AF modes that do a good job of selecting subjects and recognising their movements, yet can't always follow this up with the swift autofocus to maintain focus at all times.
Although the D5100 offers a 24 or 25fps frame rate choice at both 1080p and 720p, the resulting (1080p) MOV files equate to around 150MB per minute and have the same excess compression characteristics of the D3100's files.
There's just not the biting detail that you'd expect from a Full HD file because of this, plus exposure can 'jump' between brightness levels in certain circumstances.
Control-wise, the Programme mode takes care of all the settings and, despite the screen relaying aperture and shutter values these are only displayed as a carry-over from the stills shooting side, they're not values that apply to the movie capture - the camera takes care of all that.
The only exposure control that can be tweaked live during capture is exposure compensation adjustment.
As well as a built in mono microphone, the D5100 adds a 3.5mm microphone jack for use with external microphones. When using the in-built option it's easy to pick up lens focusing sounds, so the capacity to use an external mic is a significant and essential benefit.
Key video specifications
Approx price: £690 with 18-55mm kit lens
Sensor: APS-C sized sensor (1.5x magnification)
LCD screen: 3-inch, 921k-dot, vari-angle
Maximum resolution: 1080p capture (1920 x 1080px)
Frame rate: 24 or 25fps
Compression: H.264 video compression and Linear PCM audio
File format: MOV
Exposure mode: Programme shooting mode
Focus modes: Full time (AF-F), Single (AF-S) and Manual (MF) focus options
Connectivity: HDMI-C and mini-USB AV out ports