Today's digital cameras can shoot video as well as stills, making conventional camcorders redundant for many people. And nearly all high-end cameras can now shoot HD video, which means a massive leap forward in picture quality.
There are currently two HD formats in use:
• Full HD (1920 x 1080 pixels)
Both formats use the 16:9 'widescreen' ratio used by the latest TVs. Full HD offers the best picture quality, but standard HD shot by a good camera is still more than adequate for most casual users and even professional movie makers.
This diagram shows the relative sizes of full HD, standard HD and the 640 x 480 pixel resolution of the movie modes on older compact digital cameras (roughly equivalent to standard TV definition).
Full HD may not always offer the advantage in definition which the numbers suggest, though. This is because some full HD devices use 'interlacing' to achieve this definition. Here, two 'fields' of 540 pixels resolution are interwoven to give the impression of greater resolution.
Interlaced video is indicated by an 'i' suffix. It's common to see HDTV or camcorders described as offering '1080i' resolution, for example.
The alternative is 'progressive' video, where each frame is drawn in its entirety. This gives better results, but is not always possible at the higher resolution. Generally, standard definition devices produce progressive video, which is therefore described as '720p'.
As the hardware and technology improves, there is a move towards progressive video even with full HD, and this would be described as 1080p.
HD cameras shoot video in one of two main formats:
Motion JPEG/AVI/QuickTime
These files can be copied across from the camera's memory card and double-clicked for playback on a computer, uploaded to YouTube or imported into video editing software. It's as simple as that, and much more straightforward than the old days, where the camera had to be connected to the computer so that video could be 'captured' (recorded) in real time. The main disadvantage is file size. You need a big memory card and/or plenty of spare hard disk space on your computer.
AVCHD
This is a file format developed by Panasonic and Sony. It uses a more sophisticated compression system than the Motion JPEG format to produce movie files which take up half the storage space with little or no loss in quality. The disadvantage is that they use a complicated directory/folder structure on the memory card and can't simply be dragged across and double-clicked like Motion JPEG files. You need AVCHD-compatible software to transfer, import and edit these files, though the latest video-editing programs do provide this.
