Compared to some dedicated movie cameras, digital SLRs -- even low-end pocket snappers, for that matter -- are considerably more accomplished when it comes to shooting quality video. After all, you only need 2 megapixels at your disposal to capture Full HD (1,920x1,080 pixels), while regular high definition (1,280x720 pixels) needs less than half that number.
Imagine what you could do with an 18 megapixel-plus professional stills camera? No wonder we're starting to see a sizeable minority of broadcast and online producers using dSLRs in preference to regular video cameras.
Whether you've got a few hundred quid to spend or have three grand burning a sizeable hole in your trousers, check out my top choices below, view the test videos and click through to read full reviews of these excellent, versatile snappers.
Resolution aside, the other important consideration is the camera's scanning method -- progressive or interlaced. A progressive scan refreshes every horizontal line in the picture each time it captures a new frame. Interlaced scans refresh the odd-numbered lines on the first frame and the even ones on the next, before returning to the odd lines for the third frame, and so on.
Of the two, a progressive scan should be your preferred option as it often handles movement across the frame better than interlaced scanning.
The speed at which it performs this scan -- the frame rate -- is the third key factor affecting the digital data stream. In the US, TVs refresh the picture 60 times per second (60Hz). European sets run at 50Hz. In the best of all worlds, a camera would produce 1,920x1,080-pixel frames, refreshing every horizontal line in each one 60 times per second -- all without compressing the result so heavily that the captured footage lacks suitably crisp definition.
From a practical standpoint though, use as your benchmark the Digital Video Broadcasting (DVB) standards for high-definition video, which specify vertical resolutions of 1,080 or 720 lines, at rates of 24, 25 or 30 frames per second.
With all this in mind, let's turn our attention to the best dSLRs for capturing video.
Broadcast quality dSLR
The latest iteration of Canon's professional-grade dSLR, the Canon EOS 5D Mark III, builds on the success of its predecessor -- unsurprisingly named the Mark II. The earlier model had already found a place in many videographers' regular kit line-ups.
The £3,000 Mark III has manual control over audio recording, allowing you to set it to one of 64 levels, and an input for external microphones. This shouldn't be necessary though, as the internal mic's sensitive enough to pick up even the smallest noise if you carefully balance the input.
There's a 'silent' controller around the back that lets you tap the compass points of the regular thumbwheel while recording, rather than clicking or rotating, so you can make adjustments without affecting the soundtrack.
Maximum resolutions are 1,920x1,080 pixels at 30 frames per second or 1,280x720 pixels at 60fps.
The footage I captured in my tests was crisp and full of detail. Although the zoom is manual -- as is the case with all dSLRs -- there was no evidence of its workings on the soundtrack. Furthermore, the lens' built-in image stabilisation was more than capable when it came to levelling off motion in footage shot while walking.
The 5D Mark III's closest competitor is the Nikon D800, which is a touch cheaper at £2,600. Like the Canon, it has no trouble with Full HD resolution at 30fps progressive or 1,280x720 at 60fps progressive.
Video quality was excellent in my tests, with sharply rendered footage full of realistic colours that reflected the original scenery.
You have full manual control over the sound recording level. Again, there's an option for an external microphone, although in my tests the internal mic did a great job of recording a clean and sensitive soundtrack.
If your budget doesn't stretch to the 5D Mark III or D800, consider instead the Nikon D3200, which is altogether more affordable at £550 including a kit lens.
It hits the same resolution and frame rate specs as the D800 and it offers full control over soundtrack volume, movie quality and frame rate. The results in my tests were very impressive, with the captured footage free of skips, full of detail and demonstrating fast, smooth reactions to changing light levels.
Likewise, the £620 Sony Alpha SLT-A57, which although not technically a dSLR works and feels like one, produced a great batch of footage in my tests. Colours were punch and movement was crisp. The only slight dampener was the wind noise that remained audible on the soundtrack, despite wind noise reduction being active during my tests. Also audible were the mechanics of the auto-focus system as it maintained a fix on moving subjects.
The biggest downside in switching to a consumer device is the smaller sensor, as used in the D3200 and A57, which would reduce the effectiveness of a wide-angle lens. If you wanted to capture your presenters or characters in front of a broad vista, you'd have to spend considerably more on an even wider-angle lens to achieve what the 5D and D800 would do with a more mainstream -- and cheaper -- glass.
If you still aren't convinced that a dSLR is the best video camera for you, consider the primary benefit -- when you're not shooting movies you can also use it to take high-resolution stills.
True, many video cameras do that too, but often only at high-end smart phone resolutions and without the level of control or versatility offered by a dSLR.