Nikon Coolpix P510 Indoor Crops

Below are sample crops from an indoor photograph taken at each of the Nikon Coolpix P510's ISO settings. A crop from the Fuji X-S1
Fuji X-S1 at the same ISO setting is shown next to each one of the P510. Images below are all unmodified 100% crops from their respective cameras taken at the highest quality setting. ISO was set on camera, everything else was left on automatic.

These crops help determine which ISO settings can be acceptably used. As noise increases, most cameras compensate with noise reduction which introduces softness. The result is that, while you can partly reduce noise at the expense of details, the maximum acceptable print size gets smaller as ISO is increased. The point at which a print become unacceptably noisy is a matter of personal taste.

Nikon Coolpix P510	Fuji Finepix X-S1
ISO 100	ISO 100
ISO 200	ISO 200
ISO 400	ISO 400
ISO 800	ISO 800
ISO 1600	ISO 1600
ISO 3200	ISO 3200
ISO 6400	ISO 6400