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Wednesday, May 6, 2009

(HD) In A Nutshell

For the D-SLR shooter, there are many factors in shooting HD video

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solutionsFor the new HD shooter, high-def video is a complex medium with numerous file formats, degrees of resolution, forms of compression and frame rates. The one thing all HD video formats have in common is the widescreen aspect ratio of 16:9. The resolution currently available for D-SLRs with video capture capability is 720 or 1080, which is similar to most consumer and prosumer HD video camcorders. (In terms of resolution, the number 720 represents the number of vertical scan lines of resolution found in HDTV video with 1280 horizontal lines; 1080 contains 1920 horizontal lines.)

There are two ways that video can be displayed—either in progressive scan or interlaced. The letter “p” stands for progressive scan, which captures and displays all the lines of each frame in a moving image sequence as opposed to interlaced (“i”), which captures the odd lines and then the even lines of a frame alternately, which is now called a field. For the casual viewer, it’s often said that a progressive image has a more cinematic feel, while an interlaced image has a more immediate feel. In this regard, most narrative movies shot on video are captured in progressive mode (almost always 24 fps), while live sports and broadcast news are almost always shot in interlaced at 60i.

Regarding formats, Nikon, Canon and Panasonic all use the MPEG-4 (mp4), which is a compressed video format.
Canon uses the QuickTime MOV H.264 file format, Nikon captures in the AVI M-JPEG, and Panasonic uses the popular AVCHD (also H.264). Because of the popularity of HD consumer camcorders, almost all nonlinear editing systems (Avid, Final Cut Pro and iMovie, Premiere, etc.) now can work with the various mp4 formats.

In terms of frame rates, the D-SLRs also differ based on the model. Nikon’s range shoots in 720p at 24 fps, while Canon’s 5D Mark II shoots a higher-resolution 1080p at 30 fps. The entry-level Rebel T1i shoots 720p at 30 fps, but when shooting at 1080p, it captures only at 20 fps due to the camera’s internal processing power. At 20 fps, the image quality will be noticeably jerkier and rough compared to 30 fps when panning on a shot or when there’s a lot of movement within the frame.

Camera accessory companies, such as Zacuto and Redrock Micro, are building rigs that can accommodate “film-style” shooting (items like baseplates, matte boxes and follow-focus units), and in the near future, we’re likely to see XLR inputs for professional shotgun mics. Feature films are now in development to be shot with the Canon EOS 5D Mark II. Because of this revolution, the future is limitless in creating a new dimension with your D-SLR.


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