This week I’d like to continue the discussion of the RAW file format which all Digital SLRs are capable of capturing in. One of the biggest critics of RAW in the photo industry is a gentlman by the name of Ken Rockwell from California (www.kenrockwell.com), whose work in camera and lens review articles I read and respect. However, when it comes to talking about absolute image quality with respect to properly optimizing the information within your image, there is no substiute for a RAW workflow. The in-camera processing engines for JPEG fall short of the look and feel that can be achieved with a properly processed RAW image. Ken advocates shooting JPEGs and not bother wasting time on RAW files. I admit it is a large drag on time, unless you have a program such as Adobe Lightroom which allows for batch processing of RAW files. There are many other aspects (pros & cons) to discuss here, however that is not the point of this article.
It comes down to simple math. As mentioned in last weeks article, a RAW file captures some 65,000 levels of information as opposed to the 256 levels of information retained within a JPG image. To be quite honest, this is fine for most people, and I recommend that most people for most situations continue to shoot JPG, as I don’t care to hear about how someone can’t open their camera files on the computer because they never installed a RAW file converter. Shooting RAW requires preparation and some time committment.
When talking about RAW files, one of the biggest advantages we gain is in the area of dynamic range. Dynamic range refers to the level of detailed information that is captured across the range from shadow to highlight information. When a device has a high dynamic range, it means it can capture a great deal of both shadow and highlight data. As newer cameras keep getting better and better, we have more dynamic range options available to us. The newest Nikon and Canons (when shooting a RAW file) seem to have a dynamic range of about 5 f/stops worth of data. This is remarkable as it is far superior to what the best color negative films were capable of. Also, digital has always been notorious for loosing information (we’ll call it clipping) at the highlight end of the image. RAW files give you the wonderful opportunity of saving that data, whereas JPG files often discard the data during processing.
Beyond that, a RAW file also captures far more detail within the shadow region of an image. We can use the ‘Fill Light’ command within a RAW conversion program to relieve shadow regions and show the detail that was underexposed. Individual color channels are also kept separate within a RAW file. Let’s say you only wanted to adjust saturation or luminance for your Reds. Well, you can isolate your reds, or any other color, and do just that. The RAW conversion process also allows you to make adjustments to image contrast, overall color vibrance, image capture sharpening, and also allows for correcting lens chromatic aberration. Some will argue (as Ken Rockwell would) that letting the camera do all of this processing is far superior than what a human could ever do, but also that if you know what you are doing and can get it right in camera then there is no need to shoot a RAW file. Ken Rockwell says that JPGs are for pros and RAW files are for amateurs “who like to piddle around with their images”. I don’t know of any Pros that shoot JPG. Do you?
Next week, in our wrap up of RAW Theory I will walkthrough some screen shots of RAW processing and some examples of where RAW excels over JPG. Maybe I’ll throw in a couple other surprises as well.