- First things first: why do you want one?
- How digital cameras work
- Photo Terminology
- Camera features
- Image Compression
Movies and sound
Two additional features you may find on a higher-end camera are movie and audio. A movie feature will allow you to record a snippet of footage, which you can then play back on either the camera or on your PC. These are usually recorded as MJPEG, MPEG, QuickTime or AVI files.
Both MPEG and MJPEG files are the multimedia equivalent to JPEG and can be used for storing digital video and audio files. The difference between the two formats is that an MJPEG file saves each individual frame, rather than just saving the differences from one frame to another, like an MPEG file does. As a result, an MJPEG file will take up more memory space than an MPEG file, but has the advantage of being simpler to edit frame-by-frame than its counterpart.
AVI (Audio Visual Interleaved) is a sound and motion format developed by Microsoft for digital video in Windows. This means you will need a Windows operating system to be able to download and view these files on your PC.
QuickTime is another multimedia file type, developed by Apple. It can be used on any Mac or PC equipped with a QuickTime player, and combines images, graphics, audio and video into a single file.
As a whole, users can expect to get at least 15 to 120 seconds - and more if they have a big storage amount on their card -- of video footage on a digital camera (opting for a low resolution will increase the amount of footage recorded). A way of checking the quality of this feature across different digital cameras is to look at the frame rate: how many image frames are played back each second? A faster frame rate will reduce the time between each image frame, and make the transition between each frame much smoother. These days most modern cameras record at a resolution of 640 x 480 pixels at 30 frames per second, although there are a few models on the market now that shoot at a very high 1024 x 768.
An audio clip allows users to record a sound bite, which can then be played alongside an image or video clip. If you do buy a camera with this feature, you should get an average of 30 seconds of audio time. Audio files on digital cameras are usually saved as .WAV files - an uncompressed audio file type developed by Microsoft, which can be used both on PCs and Macs.
The hot shoe is a contact slot used for attaching an electronic external flash unit to a camera. While available on most conventional SLR cameras, this tends to be an extra feature on higher-end digital cameras and will probably only interest professional photographers.
There is a gamut of software programs now available which allow users to combine their single photos into a panoramic shot.
To help these software programs, some cameras offer a "stitching" feature which groups the photos you want to include in a panoramic shot when you actually take them. The function basically allows you to tag which image you want to include as panoramic, while the software actually joins up the images together.
Certain manufacturers are now even building such software into their cameras, allowing you to stitch together multiple shots while out and about. This is particularly useful if you aren't confident using third-party PC software