ISO explained: when to raise it and how much noise is acceptable
ISO brightens your image when aperture and shutter speed are maxed out. Learn how high you can safely go and how to keep noise under control.
ISO is the camera’s amplification of the light that reaches the sensor. Low ISO, like 100, gives the cleanest image. Higher ISO brightens the photo when you cannot open the aperture further or slow the shutter, but it also increases noise.
Why noise appears
The sensor records a weak signal in dim light. Raising ISO amplifies that signal and the random noise along with it. Noise shows most in dark, flat areas like skies at dusk and shadowed walls.
How high can you go?
Modern full-frame cameras like the Sony a7R V produce excellent files up to ISO 3200 and very usable ones at 6400 to 12800. APS-C cameras like the α6700 are about one stop noisier. A sharp photo with some grain is always better than a blurry clean one.
Expose correctly at high ISO
Underexposing and brightening later produces far more noise than exposing correctly in the camera. If the photo looks too dark on the screen, raise the ISO rather than fixing it in editing.
Use Auto ISO wisely
Auto ISO with a minimum shutter speed is one of the most useful settings for events and travel. Set the aperture you want, set a minimum shutter speed such as 1/125, and let the camera choose ISO. Cap the maximum ISO at a value you are comfortable with.
Reduce noise afterwards
Lightroom’s AI Denoise and similar tools can clean high-ISO files remarkably well. Shoot RAW so you have the most data to work with.
