How to build a light meter program?
Given a live captured image (say, on an iPhone), how to开发者_如何学Go calculate the require exposure time value programmatically based on the apertures, ISOs? Thanks!
The amount of captured light is proportional to shutterspeed*ISO/aperture.
So if, for instance, your iPhone has choosen f2.8, 1/60s ISO 800, and your camera has the constraints of f4 and ISO 100, the needed shutter speed would be 1/60s*800/2.8*4/100 ≈ 1/5s.
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