The Current Issue
Nikon Owner Issue 16
WHY SHOOT RAW? by Heather Angel
If you have recently taken the plunge and invested in a Nikon digital SLR, you may be shooting JPEG’s without considering the pros and cons of other format options. Heather Angel guides you through the technicalities.
If you have recently taken the plunge and invested in a Nikon digital SLR, you may be shooting JPEG’s without considering the pros and cons of other format options. Even if you are shooting purely for your own pleasure to produce prints for friends and family of your best shots, you should be aware that JPEG’s have the disadvantage of being compressed files. Therefore, every time you make any changes and resave, you lose some of the data; whereas TIFF files are lossless.
If you ever want to submit digital files to an image library, you will rue the day you stuck with JPEG’s, because they will require TIFF (not JPEG) files at least 45-50MB in size at 8-bit colour depth. Also, all marks from dust on the sensor have to be removed so that they are no longer visible at 100% zoom on the screen. It therefore pays to keep the sensor clean and preferably to work with two bodies in a dusty environment, so you don’t have to keep changing lenses.
How, I can hear you say, am I supposed to produce a 45-50MB file even when using a D2X camera, since when shooting a RAW file and converting it to a TIFF, it becomes a 35MB file at 8 bit colour depth? Many stock libraries will now accept digital files that have been increased in size using interpolation software such as Genuine Fractals.
All the top of the range Nikon SLRs have the option of shooting JPEG or RAW or TIFF or both RAW and JPEG files as well as various sized JPEG files. TIFF files have the advantage of recording uncompressed TIFF-RGB images with 24-bit colour (8-bits per channel), but then you have to weigh up the disadvantages. Firstly, it takes longer to process these files and secondly, they eat up memory space on your card (with a D2X and a Lexar 1GB flash card you would get only 26 large TIFF images).
RAW or NEF (which stands for Nikon Electronic Format – as Nikon RAW files are known) on the other hand, are smaller than uncompressed TIFF files (with a D2X and a Lexar 1GB flash card I can get 49 images). RAW files are ‘digital negatives’ that have to be processed for any use. You have the flexibility of converting a RAW file to either a TIFF or JPEG at a later date, whereas if you shoot a JPEG you are stuck with it. Also if you inadvertently forget to set the correct white balance (i.e. the fluorescent lighting setting is used when shooting in sunlight) this can be corrected after the image is captured, as indeed can the exposure and some other parameters.
If accurate colour is important, notably for identification of plants or animals, or reproduction of paintings or artwork, you would be well advised to expose one frame of a grey card or a Gretag Macbeth ColorChecker at the beginning of a shooting session, to use as reference for the neutrals. If you can get these right – without an erroneous colour cast – you should not need to do much to the other colours.
RAW files are captured as 12-bit data which provide more information than 8-bit data files, which makes the files larger. Essentially, a RAW file allows you greater flexibility in ways you can alter the image, either to ensure authentic colour or greater impact. The only snag is that you must use RAW converter software to convert your RAW files to TIFF or JPEG files.