Your RAW image is at its most pure, but there is no guarantee that your cameras RAW image will be recognized by available software applications sometime in the future. You may have the most up to date software to read your Nikon RAW images today, but long-term archival of your RAW files do present some concerns. Perhaps 10 years later when you want to access your archived photographs, of your family are looking for that special photo of "Aunty Jan" as a kid, or another photo that might have some historical significance that your photographs many not be accessible. This was a great concern to Photographers at the beginning of the Digital photography explosion, and even the reason why many today still shoot with film despite the advancements in digital photograph quality.
DNG file format is the answer to this concern.
DNG files also have the added security advantage of saving all of the photo information supplied with the RAW files, i.e. keywords, copyright notices and descriptions. Basically you can have your RAW file completely intact after converting to DNG.
DNG files have the ability to store full sized files or JPEG previews making it possible to preview your photographs in your selected photo viewer.
Using RoboImport (http://www.roboimport.com) as your selected digital photo management program gives photographers the ability to convert your RAW files to DNG files by including the specially developed Adobe DNG converter and enabling the option.
Most impressive is RoboImports ability to embed the original RAW file into the DNG file. Certainly this does produce a much larger DNG file, but it does allow for those occasions when you want access to your pure RAW image file. This really is having the best of both worlds.
With so much to be said of the benefits of RAW and DNG files many new digital photographers might be wondering why in the world all the other image formats may be necessary. Below is quick explanation of some other image formats. This short list is not intended as a comprehensive compilation, but just a presentation of a few of the most common.
JPEG- A common image file format that supports 8-bit color, and produces smaller files with less available information. JPEG is a compressed image format and images to suffer some degradation on conversion.
TIFF- Tagged image format is a flexible format that supports 16 bit color, or less. The flexibility of the TIFF has unfortunately created its own problems with many different variations both lossy, and lossless, some photo viewers are unable to recognize the variations. TIFF although is still supported by many printers as standard for its ability to handle device-specific color spaces such as CMYK.
GIF- Graphic interchange format is limited to a small 8-bit color palette. Gif files are very small making them ideal for internet webpages and animations.