Nikon D5300 Reference Manual - Page 200

Long Exposure NR G button ➜ C shooting menu If On is selected, photographs taken at shutter speeds slower than 1 s will be processed to reduce noise (bright spots, randomly-spaced bright pixels, or fog). The time required for processing roughly doubles; during processing, "l m" will flash in the viewfinder and pictures can not be taken (noise reduction will not be performed if the camera is turned off before processing is complete). High ISO NR G button ➜ C shooting menu Photographs taken at high ISO sensitivities can be processed to reduce "noise." Option High Normal Low Off Description Reduce noise (randomly-spaced bright pixels, lines, or fog), particularly in photographs taken at high ISO sensitivities. Choose the amount of noise reduction performed from High, Normal, and Low. Noise reduction is only performed as required. The amount of noise reduction is less than the amount performed when Low is selected for High ISO NR. ISO Sensitivity Settings Adjust ISO sensitivity (0 67). G button ➜ C shooting menu 180 C The Shooting Menu: Shooting Options