In article , Eric Stevens
wrote:

Uh, OK, looks good, but do people really go around shooting at ISO
3200? If so, why, outside of astrophotography?

Shooting high ISO is just another creative option, especially with
newer sensors. While it is optimal to shoot at native ISO there are
definitely times when higher ISO is desirable. Remember there are folks
who shoot genres other than astrophotography, or macro photography of
insects.

Today many cameras perform well in low light at ISO 3200, 6400, and to
12800 and beyond. You will find that a new trend is to use Auto-ISO
with a base ISO, a minimum shutter speed, and max ISO set. Canon,
Nikon, Olympus, Fujifilm and others all have this feature, and it works
well. I use it all depending on circumstances; fixed ISO, (native and
selected sub-native, medium, and high), and three different Auto-ISO
set-ups.

All OK, but high ISO cuts down the possible dynamic range.

better to have low dynamic range than nothing at all.

Keep it low
if you can.

*if* you can. it's not always possible, and also why auto-iso is a good
choice.