Why and what are RAW or JPG?
This will sound dumb, but you don’t have to shoot raw to have a raw workflow. All the major raw developing software also work with JPG files. So you can experiment without having to change much to start off.
A Raw file is…
• Not an image file per se (it will require software to view it, e.g. Picassa or Sony’s Image Data suite that came with your Alpha)
• Typically a proprietary format (with the exception of Adobe’s DNG format that isn’t widely used “yet” and as far as I know all Alphas .ARW raw file extension ).
• At least 8 bits per colour – red, green, and blue (12-bits per X,Y location), though most DSLR cameras record 12-bit colour (36-bits per location).
• Uncompressed (a 14 mega-pixel camera will produce a 14 MB Raw file).
• The complete (lossless) data from the camera’s sensor.
• Higher in dynamic range (ability to display highlights and shadows).
• Lower in contrast (flatter, washed out looking).
• Not as sharp.
• Not suitable for printing directly from the camera or without post processing.
• Read only (all changes are saved in an XMP “side-car” file or to a JPEG or other image format).
• Waiting to be processed by your computer.
A JPEG/JPG is…
• A standard format readable by any image program on the market or available open source.
• Exactly 8-bits per colour (12-bits per location).
• Compressed (by looking for redundancy in the data like a ZIP file or stripping out what human can’t perceive like a MP3).
• Small in file size in comparison to a raw file (a 14 mega-pixel camera will produce JPEG between 1 and 5 MB’s in size dependant on the situation and settings).
• Lower in dynamic range.
• Higher in contrast.
• Immediately suitable for printing, sharing, or posting on the Web.
• Able to be manipulated, though not without losing data each time an edit is made – even if it’s just to rotate the image (the opposite of lossless).
• Processed by your camera.
The Important differences …
Raw files are much larger than JPEG files. The “camera” has already decided how and what should be changed in the final image, and stripped and “unneeded” information away. That extra information is what makes raw data so “powerful” what it comes to developing your raw images. Every time you save a change to a JPG/JPEG file it will be compressed again and more information will be stripped away, therefore IMHO the JPG file is truly only usable as a final product. The quality of a JPEG taken with your Alpha DSLR will still be better than the same shot taken with a point and shoot camera that is the same age as your DSLR. When you shoot in burst mode (continuously for a few seconds or longer) you’ll actually be able to shoot more shots consecutively using JPEG than Raw, because the slowest part of the whole process is actually saving the file to your memory card and the raw files are much larger.