The Nikon Electronic Format RAW file format is exclusive to Nikon digital devices and provides a number of benefits over the other file formats such as JPEG and TIFF. NEF files saved in Nikon digital cameras are referred to as NEF RAW files. Files can be saved in either an uncompressed or compressed form, although some models such as the D70s and D50 only offer the latter option, where using what Nikon describe as a 'lossless' compression scheme file size is reduced to approximately 50-60% of the original.
There are two principal advantages in using the NEF RAW file format.
The first relates to the fact that NEF RAW image files contain 12-bit data and therefore have a far greater tonal range compared with 8-bit files such as those saved in the JPEG and TIFF format, which allows much finer control of colour and helps reveal more detail in shadow areas.
The second concerns the lack of processing applied in camera to the image file data, which provides far greater flexibility in the use of the image file at subsequent stages. For example values for the White Balance, Tone, Hue, Sharpening, and Size/Resolution are not applied to the original image file data but retained in the file as a separate set of instructions. Likewise NEF RAW files are not processed by the camera to RGB data as happens with JPEG and TIFF files but colour values are stored with in the file as another set of instructions. The instruction sets can be altered at any time after the exposure has been made using both Nikon and third party software. Provided the original data is maintained in the NEF RAW file format any number of derivative files can be made from it; the processing instructions are only applied to the image data when it is saved in an alternative format such as JPEG or TIFF. This ensures that the maximum amount of data is available during the image editing process, which helps to maintain image quality.
Furthermore, when a NEF RAW file is edited using Nikon software the editing instructions are saved as a distinct and separate set to the original instruction set saved at the time of image capture in the camera. Thus editing a NEF RAW file does not affect the original instruction set, so the original data is always available allowing any manipulation of the image file to be undone. If you produce a new variation of a NEF RAW file by editing the only additional data that has to be saved in the image file is a new processing instruction set that requires a few kilobytes of information, compared with the megabytes of data that an entirely new image file would require if saved in an alternative format.
Shooting in the NEF RAW file format allows you to extract the maximum image quality from your camera, whilst permitting the original image to be processed in a number of different ways depending on how you want to use the picture. It is for this reason that many photographers consider a NEF RAW file to be analogous to a film negative.
The following Nikon software applications can be used to open NEF files:
PictureProject, Nikon View (versions 5 & 6), Nikon Capture (versions 3 & 4). It is also possible to open NEF files in Adobe Photoshop 5.0 or later (excluding Photoshop LE) and versions of Photoshop Elements using the Nikon NEF plug-in supplied with PictureProject and Nikon View 5 (versions 5 & 6).
To open NEF RAW files directly in Adobe Photoshop you can use the Adobe Camera RAW (ACR) converter (see adobe.com/downloads for details). Currently, Adobe Photoshop 6, 7, CS, CS2, and Photoshop Elements 3 support this function.