Originally posted by Shadus
Jed did gave me a good grounding on USM principles at a later stage. Hope he'll make some comments here 
What? You actually think I have the time to wallow around in a Canon forum?
Try asking the question again in the Nikon forum, I might answer then, after all, cannot have Canon users benefitting from my knowledge right :bsmilie:
Seriously, yes I've been down this road before. There is no standard USM setting. Quickly again off the top of my head, the following are all
big factors to play:
[1] Starting resolution. A 3000x2000 pixel file needs VASTLY different USM settings from a 300x200 pixel file. Try it with the same settings and you'll see what I mean. This alone makes it ridiculous for anyone to state a general setting they use all the time, unless they only have output at a single resolution. Since USM should always be the last process before output, this is highly unlikely.
[2] The subject matter of the picture. A file with intricate details needs different sharpening than a file with strong bold lines but no intricate details. And a full range between those two extremes.
[3] The cleanliness of the file. A noise-free file with take more effective USM-ing. You have to sharpen a noisy file differently.
[4] Target output. A file destined for inkjet printing, dyesub printing, screen viewing, etc, all require different amounts of USM.
Several other points raised in the thread that I want to raise issues about:
[1] I shoot at JPEG Normal all the time when working. When I shoot for myself, I'm 50% JPEG Normal, 40% JPEG Fine, and 10% RAW (and bear in mind my RAW actually gives me a gain in real pixels along the way as well). While I haven't done a scientific test, here's food for thought. I routinely use JPEG quality of 10 (out of 12) in Photoshop. The files it generates are actually
smaller than an equivalent file that comes out of these cameras in JPEG Normal, let alone Fine. For me anyway, the increased file sizes makes speed and storage a nuisance. Not just at the taking stage, but at the archiving and accessing later on. It adds up. I work with thousands of images a week, it makes a big difference.
[2] This not sharp thing. Ignoring the difference between cameras, you have to remember that looking at a several megapixel file in full resolution on screen is usually the equivalent of scrutinising a HUGE print. Depending on camera and monitor resolution, usually somewhere in the region of 20x30. A lot of stuff looks sharp at 8x10, which is why sloppy technique when shooting film can sometimes be got away with. But the same applies to dig in reverse; as in, sloppy handling with the dig, yielding not critically sharp pictures, while unuseable at 20x30, could possibly be quite useable at 8x10. But I must stress that I'm NOT advocating the encouragement of sloppy technique.
