NR 1 vs. NR 2 and Noise in General Question
 

I own a XH A1 and have a couple of questions.

I realize NR 1 causes ghosting, but at what point does it become noticeable? Meaning, how much camera and subject movement must occur in order to ghosting to become a problem? (I realize this might not be the best question since there isn't a "camera/subject movement scale".)

Correct me if I'm wrong, but NR 2 reduces noise at the cost of fine detail. So how fine must the detail be in order for it to be lost? Or to put it another way, if 98% of my subjects are people, will turning NR 2 to Low result in a noticeably softer image?

And lastly, at what point do you recommend that I turn on some form of Noise Reduction? If my gain is set to +6? Or more?

First it will very much depend on the image content (including motion), the specific NR settings you are using, your exposure and other profile settings, and lastly, but perhaps most important, your (and your client's) standard for how much NR artifact is "too much."

The same applies as to when to use RN. Image noise become more apparent when gain is added, and to a somewhat lesser extent when slow shutter speeds are used.

Each user may have different requirements, and each project and client a different tolerance for image noise vs. NR artifacts. Thus it becomes an individual choice based on your circumstances. There is no hard/fast rule. Some folks might even want the NR artifacts as an artistic effect for some shots; e.g., use high setting of NR1 with lots of motion to show a dazed victims view of a scene evolving in front of them. And some wedding shots do call for a soft image to mask facial lines (there is a skin detail function for that) but this might help if the range of completions are too great for the skin detail function.

If you need a starting point benchmark: I believe that for many purposes and "average" (what ever that means) image content, NR is probably not needed at +6 dB or lower gain, a toss-up at +12 dB, and usually helpful at +18 dB. Use NR1 when the image contains slow or limited motion. Use NR2 when you have significant motion or when a somewhat softer image is acceptable. Use the least amount you can, and play with it, test different setting on practice shoots, to get a feel for how much works for you before you have to rely on it in a money shoot.

And perhaps most important, try to add light if you can before you add NR.

I never use greater than +3db for a controlled shoot (i.e. I'm lighting it), +6db if I'm desperate (e.g. at the long end of the lens and unable to quickly/easily lift light) for a shot or two, and the content is intended to be at least somewhat gritty. For event style work, I use +6db without a second thought-- NR1 off, NR2 low. Also for events, +12db I'll use if I have to, with NR1 low, NR2 low or medium. Never used +18db. The NR1 ghosting (at low) isn't particularly objectionable for low/medium motion, and if you're shooting events then it's within the realms of acceptability. You'll notice it but likely no one else will pay attention. For anything controlled, I consider NR1 entirely unacceptable, while NR2 is pretty subtle and can give a slight (even desirable) softening in some cases. Connect your cam via component to a HD TV and play with the settings-- remember to include Coring in your tests. note: NR1@low will look worse while swinging the camera around your room, than it typically will in the real world ;)