The first video-capable DSLRs were aimed at photojournalists, but were quickly adopted by wedding photographers and even serious filmmakers. The large sensors (relative to those found in pro camcorders) allow for cinematic limited depth of field and thus effective selective-focus shots. HDSLRs are much smaller and far less costly than the pro digital camcorders, and the lens selection is extensive. Plus, you also got an outstanding, high-tech still photo machine. But there's more to shooting videos with your HDSLR than just pressing the "movie" button. The artistic aspects of filmmaking are beyond the scope of this article, but here are some things you should know about using HDSLRs to shoot videos.
There are a number of video resolutions, and most of today's DSLRs can shoot several. HD (high-definition) video is 1280x720, meaning each image consists of 720 horizontal lines, each 1280 pixels wide. Full HD is 1920x1080, or 1080 horizontal lines, each 1920 pixels wide. (Note that 1920x1080 is just 2.07 megapixels per frame.) Some DSLRs (and many older compact digital cameras) also can shoot VGA video (640x480, not useful for professional purposes). SD (standard-definition) digital video is 720x480; no HDSLR shoots that.
Full HD 1920x1080 is great, but there are even higher-resolution formats, most notably 4K, with images about 4000 pixels wide. The 4K Ultra HDTV standard is 3840x2160—four times the spatial resolution of 1920x1080 full HD. Canon's EOS-1D C does 4K at 4096x2160. RED offers still + motion cameras that can do 4K at 3840x2160 (1.78:1 aspect ratio) and 4096x2304 (1.9:1 aspect ratio). RED also offers cameras that can shoot 5K video—5120x2700 (1.9:1 aspect ratio) and 5K WS 5120x2134 (2.4:1 wide-screen aspect ratio). Ultra HD 8K is 7680x4320—16X full HD's 1920x1080. Announced at NAB in April, RED's newest camera model, the RED EPIC DRAGON, offers 9X the resolution of HD files with a 6K sensor capable of 6144x3160 resolution with up to 6K and 5K acquisition formats; 2:1, 2.4:1 and anamorphic 2:1 aspect ratios are available, as well as 16:9 when capturing in 4K, 3K or 2K/1080p/720p.
The aforementioned figures are in-camera recording figures, of course. The resulting videos can be played back on a variety of media, from digital cinema (movie theaters) and home HDTVs to computer monitors, iPads and even mobile phones. Today's digital theaters generally use 2K (2048x1080) at 24 or 48 fps, or 4K (4096x2160) at 24 fps. Standard digital television is 640x480 (4:3 aspect ratio) or 720x480 (16:9 aspect ratio). Apple's top MacBook Pro has a 15.4-inch Retina Display that uses 2880x1800 (220 pixels per inch). The top iPad has a 9.7-inch Retina Display using 2048x1536 (264 ppi). The iPhone 5 has a 4-inch Retina Display using 1136x640 (326 ppi).
The 4K, 5K and 8K formats are the wave of the future, and if budget allows, it's not a bad idea to shoot 4K to provide some future-proofing. However, today many pro projects are done quite satisfactorily in 1080p. And keep in mind that the higher the resolution, the larger the image files, and the more powerful the processors needed to deliver usable frame rates in-camera (and afterward, to edit the resulting footage in your computer). Four minutes of compressed 1080 full HD results in a file size of around one gigabyte; 4K files are 4X that size.
Most DSLRs shoot 1080 full HD at 24 or 30 fps (some offer both, and a few even 60 fps). Common 720 HD frame rates also include 24, 30 and 60 fps. VGA usually goes at 30 fps. These are NTSC frame rates, used in the U.S. and some other areas. Much of the rest of the world uses PAL, which has standard rates of 25 fps and 50 fps, something to beware of if you're thinking about buying a gray-market HDSLR.