K10D noise reduction at slow speeds

Hi All
Has anyone any experience with using the camera's N/R at 1600 ISO? Do you know at what speed the N/R kicks in? Has anyone made any systematic tests to determine the optimum exposure level gives the best results?
My impression is that a fully exposed image may be relatively noise free even at 1600 ISO.
I feel that we may be overly pessimistic as to the usefulness of this setting.
Do you agree?
Ron McDermott

Personally, I never use it, preferring to do image enhancement on computer, where there is more power and more sophisticated software available.

G

AFAIK, the in-camera noise reduction just does dark frame subtraction which takes a second "shot" with the shutter closed and subtracts the noise from the original image.

This helps to lower the noise and hot pixels, but as George rightly says you can do a much better job on the PC. The only small thing worth noting is that the noise will vary with ambient temperature and the temperature of the CCD sensor and the in-camera noise reduction can help to some degree... unless you take your own dark frame for later subtraction

Matt

Noise reduction won't activate unless you have st it in the Custom menu. There are some images with it on/off here http://www.ephotozine.com/article/Pentax-K10D-1

I'm not sure at what shutter speed it kicks in, I think it is some significant fraction of a second.,

Thanks friends for prompt and clear replies.
Ron McDermott