ISO 80 produces clean, sharp images...
...as does ISO 100.
But by ISO 200 a hint of softening begins to creep in.
This softening is more accentuated by ISO 400
By ISO 800 there's a noticeable loss of detail especially in shadow areas.
ISO 1600 is pretty noisy with a big loss of detail.
The top setting of ISO 3200 is best avoided if possible.