Interactive

How exposure and focus work

Brightness is only half of it. The same settings also decide what is sharp, how the background falls away, and how out-of-focus highlights turn into bokeh. Drag the controls and watch one scene react. These basics are the same for every camera, infrared included.

The short version

• Aperture (f-number): lower lets in more light and makes focus shallow, so things fall out of focus fast; higher is dimmer but keeps more of the scene sharp.
• Focus: only one distance is truly sharp. Everything nearer or farther softens, and aperture sets how quickly.
• Bokeh: the soft glowing discs that out-of-focus highlights turn into. Wider apertures make them bigger and rounder.
• Shutter speed: slower lets in more light but blurs movement; faster freezes movement but is darker.
• ISO: higher brightens the image but adds grain; lower is cleaner but needs more light.
• Zoom / focal length: longer frames tighter and throws the background further out of focus.
• Aperture, shutter, and ISO trade off against each other for brightness. Open the aperture and you can use a faster shutter or lower ISO for the same exposure.