Grain is recoverable and camera shake is not
The trade
Higher ISO adds grain and allows a faster shutter. Grain is a texture; blur is lost detail, and only one of them can be improved later.
The shutter rule
Hand-held, keep the shutter faster than one over the focal length. At fifty millimetres that is a fiftieth of a second, and slower than that needs support.
Support
A wall, a bag on a railing, or elbows on a table. Any of them buys about three stops, which is more than any ISO change.
