tedster - 12:28 am on Mar 25, 2001 (gmt 0)

What I do is select the channel to blur, but then click the eyeball icon on "L-a-b", the composite view, so I can preview the final effect. I just push the slider until the image degrades visibly and then back off. Blurs in the 3-4 pixel range are common.

No, this technique doesn't give huge savings, but on a big enlargement, it's helpful.

BTW, a lot of times with digital photography there is some digital noise, but it's almost always isolated to one color channel in L-a-b, making it the best place to handle such issues. Also great for fixing bad color-casts.