Why do cameras still need ND filters?

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Obviously it was a thing for film cameras, but now that everything is digital, something like “just make the picture darker” seems extremely easy to do with software

quick edit, I know what ND filters are for and how to use them, no need to explain. it just seems to me that it could be engineered in a way that doesn’t require them, which is what I’m asking about

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26 Answers

Anonymous 0 Comments

There are three main settings in a camera, ISO, Shutter speed, and aperture.

ISO is how sensitive the digital sensor is. Higher numbers artificially boost the amount of light, but degrades image quality

Shutter speed is how long the camera lets light in for. Slower speed means more light, but more blurring from motion

Aperture is how large the shutter is overall. Wider aperture means more light, but effects how in focus near and distant objects are.

For video work, you want a certain amount of motion blur, or the video will look “off”. So a specific shutter speed is desired in many cases. You might also want everything behind the object to be “blurred” out, so you use a wide aperture. The problem is now you have too much light and the whole scene will be white, you can’t digitally darken a pure white scene, because it’s just one color and nothing else. You can’t lower ISO below a certain amount either, so instead, you put a darkened piece of glass over the lens to lower the light level.

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