djon said:
Francesco....why is saving RAW better than saving TIFF, since both are loss-less? You can see my level of digicam ignorance...
Raw (there's no reason to capitalize it, since it isn't an acronym for anything; it's just a word, "raw," as in unprocessed) is better than TIFF (Tag Image File Format) even though both use lossless compression, for a couple of reasons:
-- Raw files record the actual data read off the sensor without any post-processing. This gives you the chance to apply more-powerful post-processing software than can be built into a digital camera. Usually you have a choice of post-processing software options (camera manufacturer, Adobe Camera Raw, Phase 1, etc.) and can choose the one that gives the look you like and has the features you want to apply. This is an overworked analogy, but it's a bit like the b&w film world, where some people prefer Diafine, some prefer Rodinal, some prefer D-76, etc.
-- TIFF images (as well as JPEG and other file formats) require post-processing of the raw sensor data to yield a file in a standardized computer format. There's more to this than just putting a different header on the same data; the brightness and color values of each pixel have to be derived mathematically by combining information from the imager's "pits" in various combinations, and with various correction factors applied for sharpening, removal of false colors, etc. If you're generating these files in-camera, you're limited to the amount of processing power that the manufacturer can build into the camera, and you can't take advantage of more sophisticated postprocessing algorithms as they become available (other than what the manufacturer can pack into a firmware update.)
-- A small but important advantage of raw vs. TIFF is that since the raw image is unprocessed, it contains more data but occupies less file size than the equivalent TIFF image. This smaller size translates into more images on your memory card and less file-writing time between shots.
When I first got started in digital photography, I used to think the raw-vs.-processed issue was just a big con job; I shot everything in max-quality JPEG and got files that looked good to me, so what was the big deal? (To some extent I was justified in thinking that way, since there were very few options for raw-file conversion back then.)
Once I got more experience, though (and once raw-processing software became more diversified) I realized that it's not just about "quality" (whatever that means), it's about
choice. Shooting in raw gives you more choices in how you'll get from the original scene to your final photograph.
Again, I feel digital-to-darkroom analogies are generally overworked, but can you imagine how frustrated the serious b&w enthusiast would be if you told him that the ONLY film he could use was, say, Ilford Delta 400, the ONLY developer in which he could process it was Ilford DDX, and the ONLY paper on which he could print it was Ilford Multigrade IV? These are all fine products, and you certainly can get good results with them, but serious photographers want more choices so they can exert more control.
It's the same thing with raw. It's not necessary for a snapshot or casual digital camera, but I can't imagine spending serious money on a digital camera that did
not offer that capability.
