A year ago, if you had asked me what format was best to shoot in, I would have said--without hesitation--to use JPEG. It's not that I love JPEG's tendency to compress your files, and therefore compromise image quality. It was that JPEG was the best way to quickly and efficiently capture and edit digital photos.
That's still mostly true. But while RAW was once an arcane and difficult format to work with, these days RAW support is built into all the major image editing suites. So if your camera has a RAW capture mode, and you've been interested in trying it out, now is a good time.
What's RAW? And Why Use It?
Believe it or not, RAW is not really a single file format at all.
Every camera manufacturer has its own native file format; collectively, all these formats are referred to as RAW. Canon RAW files use the .crw and .cr2 extensions, for instance, while Nikon cameras create .nef files. They are all unique and proprietary; the files in these various formats are incompatible.
But no matter what flavor of RAW you use, the idea is the same. RAW files are uncompressed, pristine representations of what the camera's image sensor captures when you press the shutter release. RAW images are totally unprocessed. With JPEG photos the camera performs a host of tasks such as white balance adjustment, color correction, and image sharpening. Perhaps most importantly, RAW files preserve all of the colors originally captured by the camera--usually 12 bits per pixel. When a picture is saved as a JPEG, the camera reduces the total number of colors to just 8 bits per pixel. RAW's higher color fidelity adds up to better photos, especially if you edit your images.
So how do the two formats compare in real life?
Here's a detail from a photo I took with a Nikon D100 camera in JPEG set to the highest quality. The same subject, captured in RAW, looks slightly less noisy due to the lack of JPEG color fringing; but otherwise, it's pretty much the same. As a point of comparison, I ran the JPEG version through Noise Ninja ($35), a noise reduction filter. The result is better than the RAW image.
Of course, this is just one example, and it fails to illustrate the benefits of editing with higher color fidelity. I just wanted to demonstrate that there's nothing magical about shooting in RAW.
The Downsides to RAW
There are some disadvantages to working in RAW.
First and foremost is the time it takes to save each image on your camera. Most modern cameras can save even large JPEG images more or less as fast as you can shoot them. But RAW images are another story. On my 6-megapixel Nikon, for instance, each RAW image takes about 40 seconds to get saved to the memory card. That adds up to 2.5 minutes to empty my camera's four-picture buffer, which is the equivalent of 14 eternities in picture-taking time.
File size is another consideration. My top-quality JPEG images clock in around 2.5MB each, but their RAW counterparts are a somewhat heftier 4.5MB. That's not as big a deal as it used to be, since you can now buy a 1GB memory card for less than $100. But if you have a smaller memory card, it's worth considering.
In a couple of weeks, we'll continue this discussion of the RAW format with a look at how RAW works once you get the pictures from your camera to your computer.