I have a small photography school in Meltham, Holmfirth, West Yorkshire. I give private individual or small group photography lessons. See my website for details there's a link above this. The following is a brief explanation of Raw files.
Raw is the format for the enthusiast and professional photographer. Almost all cameras that shoot RAW have a different format so will need some software to deal with them on your computer. Your camera will probably be bundled with some software but it's usually either the camera manufacturer's own or a budget version.
Raw is exactly what it says unprocessed raw digital code, all of it that your camera captures. 'Lossy', formats such as Jpeg compress the image, losing information as they do so. Raw enables you to process data later with better software than your camera has. Your camera has a tiny brain compared to your computer and cannot compete when it comes to processing – the camera is for capturing information.
Your camera actually makes a jpeg preview every time it creates a raw file, this allows you to see roughly what you have captured, a raw file is simply a string of code, it cannot be viewed as an image. When you load your raw file into the software it will create its own, better preview jpeg. You can then work on that image without altering the raw file. You can also create virtual copies i.e. colour, black and white, sepia whatever.
The raw file cannot be altered. I liken it to playing a CD, you can alter the bass, treble etc as you go along but the data on the CD never changes. The changes you make to the image are stored in a catalogue which remembers where that image is on your computer and how you would like it to look as a jpeg. It is wise to make at least one copy of that catalogue on a separate hard drive.
You can also create a sidecar or XMP file which sits alongside your raw file and remembers all your work. A belt and braces approach yes but its worth doing.
These images are previews of the same raw file, the colour one is as shot and the others are virtual copies given treatment in Lightroom.
