What do you considering the upper limit for ISO?

RichA wrote:
Can you produce a shot worthy of keeping at 6400 ISO?

Been there, done that. 20D, ISO 1600, push 2 stops in post.
Standard diet.
Of course, that's 5 years old technology, todays' cameras
will do better.

I shoot a D300. IMO, beyond 800 ISO I have trouble accepting the
images as really good.

If you print it at 1m x 1.5m and touch it with your nose, you'll
always see noise or artifacts. Just like film grain. Learn to
live with it.

I'm talking about non-noise reduced raw
images. Sometimes, it's possible to use NR and not make the picture
look like crap, but the leeway is narrow.

And here I thought there was some huge difference between "crap"
and "really good" ...

.... and that the subject depicted had something to do with it.
Say, if you go into a museum, do you call all the paintings crap
because you can see where the brush put the oil on the canvas,
if you look closely?

-Wolfgang