ISO is quickly explained — yet it is one of the most common mistakes when filming yourself. You turn the slider up, the image gets brighter, and you think the problem is solved. But it isn't.

What ISO actually means

ISO comes from analog photography — back then, it was the light sensitivity of the film. Today, it is the sensitivity of the digital sensor. A low value (100–400) means: the sensor reacts little to light, and the image is clean. A high value (3200, 6400 and higher) means: the sensor amplifies the signal — but it amplifies everything, including the noise.

Noise is the enemy

Image noise looks like sand over the picture. It starts appearing earlier in dark areas and holds back longer in bright ones. With a modern full-frame sensor, you can go up to ISO 1600, sometimes 3200, without it being distracting in the final video. With a small sensor — as in many budget cameras — you're often at your limit at 800.

The trick: do not turn up the ISO first when it gets dark. First, open the aperture. Then adjust the shutter speed. ISO is the last option, not the first.

The Exposure Triangle

ISO, aperture, shutter speed — the three influence each other. If you change one, you must compensate elsewhere. Understanding this is the difference between full auto and conscious filming.

Best regards,
Sascha Manke