civilized ku # 890 ~ vision / craft / on seeing continued
Saturday, March 12, 2011 at 01:07PM 
Reflection ~ Au Sable Forks - in the Adirondack PARK • click to embiggenlast Thursday's entry, decay # 42, raised a few points that require a bit of clarification, so ...
ISO bracketing is an in-camera capability - I don't have any idea which cameras have it and which don't - that creates 3 bracketed image files from 1 click of the shutter. I use this bracketing capability because, while making a picture, it does not require a tripod to insure precise registration between the bracketed image files - each bracketed image file is derived / created from the same "original" image file. And, in the case of subject motion, it is the only way to bracket without registration issues.
In some ways, in-camera ISO bracketing is similar to triple-processing a single RAW file - 1 stop under, normal, and 1 stop over, a technique that I use on occasion. However, it is not the same. Under and over processing runs the risk of increased noise and processing artifacts (shadow areas) and color problems (in "recovered" highlights), both of which can be avoided with ISO bracketing.
Color accuracy issues can not be solved by using a "pro level" camera. Every camera sensor together with its color engine (and all of the associated limitations thereof) produces its own idea of "pleasing" color in a fashion that is not completely dissimilar to that of different color film stocks, none of which are color accurate. Add to that fact the realization that every RAW converter produces image files with differing results (from identical files), the idea of color accuracy is a thorny one indeed.
Recommending Curve learning resources is not area in which I have any experience. That's simply because I never read a single book, attended a how-to seminar, or the like. However, I used the google and came up with 2 possibilities, one rather simple and easy to digest, and one a bit more expansive.
Reading either link will not make you an adept PS Curves user - that can only come from spending 100s of hours (or more) screwing around with the tool. That does not mean that everything you do or try to do with Curves will be crap until the day you are an "expert". It just means that the more you work it the more you'll come to understand the tool's possibilities and limits.
IMO, the best way to log those hours is to start with an image file that has room for improvement and process the living life out of it a hundred different ways to Sunday. A manifest beauty of the digital darkroom is the fact that you "destroy" / over-process a file and, assuming you do it on a copy, throw it away and start all over again. And, even in the midst of a processing frenzy, there is the magic of the history palate and the undo command - make as many "mistakes" as you like. In fact, make deliberate mistakes because, unlike real life, you can go back and do it over again, and again, and again, and again ... and you never have to say you're sorry.
When starting out with Curves, it is a good idea to make a copy layer of the image and process it (leaving the original layer untouched). This allows you to toggle the copy layer on and off in order to get a quick look at what you've done relative to the un-Curved layer. It's a great way to get instant feedback, every step of the way, on what you've done.
Sven W mentioned a book that "You could spend a year studying ...". IMO, that's exactly what's wrong with so many Photoshop tutorial books - they are more of an authorial ain't-I-smart tour de farce than they are a practical guide to getting things done. That's why I have avoided them like the plague.
However, way back in the early days (1991 / Mac IIci / Photoshop 2.0) when I first turned on computer, I did use one of Peachpit's Photoshop Visual Quickstart Guides. These guides are task based tutorials - no theory or long-winded overviews / bullshit, just simple easy to understand explanations, with lots of illustrations, about how to get specific PS tasks done.
Reader Comments (4)
Thanks for the clarifications Mark about the ISO in-camera bracketing and the Curve tool issue. You share good food for thought and like you write: practice, practice, practice is the way to go to improve our skills!
I have to agree with your reply to Swen re Photoshop books. You can spend a year studing a book and get only one view, while in a half day with Google you can sample a dozen different views of the matter to find the one (or the combination) that fits what you are trying to do.
No matter how much a person studies, though, photography is like sports or music. The only way to really learn it is to do it. Do it over and over and over until you can't see any way to do it better.
@Mark, Gato : I wasn't implying you should study the one book to the exclusion of all else. A more expanded version of what I am saying is that the [Ctein] book gives a lot of insight and practical application into the various editing tools (e.g Curves). You walk away with the clear message that they are *tools* that need to be driven by you and they are not a) random b) mysterious c) a silver bullet. But they are essential and not some peripheral consideration.
Also FWIW, some people's preferred learning method might be to experiment endlessly. My approach is to get some concepts and tips upfront, from someone who knows that they are doing (i.e I like their work).
Further, unless you have a natural talent then practising without some upfront knowledge can easily lead you down the wrong path.
Just sayin'.
ISO bracketing: this concept is new to me and unfortunately my camera only supports "shutter speed" bracketing. The nearest thing I can do is shoot a single RAW and in the RAW converter generate three "exposures" then exposure blend.
I took some previously processed images and put them thru this new workflow: RAW --> faux ISO bracket 0, +1, -1 --> 16 bit TIFF x 3 --> HDR --> 16 bit TIFF --> usual edits --> JPG.
The 16 bit TIFF from the HDR stage yielded a nice surprise: the colour was a little cleaner. Don't ask me how, but normally the TIFF from the RAW converter had a slight (very slight) smudgey reddish tinge. Now it's pretty well gone!