My post above was aimed at what was right for a new photographer since that was sort of the thrust of this thread. And to that end, I was talking mainly of the advantages of shooting RAW to make things easier. Which it certainly does by removing the burden of making your processing adjustments before or during shooting.
BUT, there are other benefits to RAW that extend beyond just making things easier, and these give reasons for even the "perfect" photographer to shoot RAW too.
John was alluding to those differences in his post.
I look at RAW as being similar to shooting print film, and I look at in-camera-JPG as being akin to shooting slide film.
With slide film or in-camera JPGs, you must expose to get a final product that looks exactly how you want it to look. In other words, if you're shooting a dark, dim scene, and want the final image to look dark and dim, you MUST expose low so that the final product is dark and dim. This is true with slides or JPG because you get no second chance to adjust things (properly - more on that later).
With print film or RAW, you can expose every scene "to the right" to maximize the dynamic range and minimize the noise in the capture. This is true because there is always one more step in the process where you can adjust the "brightness" of the image down to achieve a final output that is dark and gloomy if that's what you're after.
With print film, you make that adjustment when you expose your print. We never want to have a "thin" negative, even for what will be a dark print. We want a "perfect" negative and we just expose the print paper longer if we want a dark print.
With a digital RAW, you make that adjustment when you process the RAW file. We never want an underexposed capture, even for a dark final image. We want a "perfect" digital capture, and that means always having the brightest highlights of interest end up just shy of clipping. This maximizes the DR and minimizes the noise in the capture. If we want a darker final image, we simply adjust the "brightness" downwards when we make our RAW conversion. That pushes noise down. And we've maintained detail in the dark areas because they're not exposed so low that they're buried in noise or represented by too few quantizing "steps".
So RAW is better than even a linear bitmap like TIFF would be. And the JPG compression makes it even worse.
Since our only non-RAW choice in the camera is a JPG compressed version of the converted RAW, we lose even more when we do not use RAW. JPG compounds the problems of throwing away the RAW data.
JPG compression was designed to be used on FINISHED bitmaps to reduce file size. It works very well and the results look great... UNTIL we try to make adjustments to brightness, contrast, curves, saturation, etc. JPG was never intended for this. It was meant to be the FINAL version. And if you use it as such, then it's pretty good. (Again, think slide film here).
JPG compression involves using a non-linear compression of the dynamic range so that the full DR of the shot can be represented in an 8 bit format. When you make adjustments, you reveal the limitations of that compression. The result can be posterization and other bizarre color-shifts and distortions. Not good.
Also, JPG compression plays clever tricks to eliminate subtle shading details that it thinks won't be visible anyhow. Again, this works well until you start making adjustments at which point, you can reveal the limitations of the JPG compression.
And finally JPG throws away fine details that it, again, thinks won't be too visible, or will be masked. This means that for many images, the JPG version will simply lose a lot of very fine detail.
To me, if I want the best possible large prints or high quality work, I never consider using JPG compression until the very last step. Often, not even then for large prints. I stick with 16 bit TIFF format to the bitter end.
So even if you do own a crystal ball, and can predict, without fail, exactly what processing parameters you'll want for every shot before you even take the shot, you are still losing a lot of benefits by shooting in JPG-Only mode. I would never consider it unless there was some overriding benefit to it. And that means, I'd have to be very low on CF space OR be shooting a burst that actually required more than 17 shots!!!
--
Jim H.
