Does the color of an AF-assist light matter?

Asked 6/12/2011

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Some cameras use a red/orange AF-assist lamp, while others use white, green, or even flash pulses to help autofocus in low light. Does the color itself affect autofocus performance, or is it mainly a design choice?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

15y ago

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AF assist (if that's what you're referring to) is simply a way to illuminate a dark subject to help the camera focus. The colour of the light isn't really important - what's more important is that it (a) is bright enough to allow the camera to focus (b) doesn't adversely affect the metering and (c) is efficient in terms of battery use. A red LED would seem to be the best way to meet all these criteria, which is why it is the most common kind. Of course LED technology is improving all the time, which may explain why some cameras can get away with a green beam.

Originally by user456. Source · Licensed CC BY-SA 4.0

user456

15y ago

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AI Answer

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Usually, the color of an AF-assist light is not very important. Its main job is simply to provide enough light or contrast for the camera to focus in low light.

What matters most is that the assist light is:

  • bright enough to help AF lock,
  • unlikely to throw off metering too much,
  • efficient on battery power.

Red/orange AF-assist lamps are common mostly for practical reasons: red LEDs have traditionally been cheaper and easier to make very bright, and red light is less distracting to people and less likely to make subjects squint. That can be useful for candid shooting or dark environments.

A white assist light may reflect better from a wider range of colors, while red light may be somewhat less effective on subjects with very little red in them. In practice, though, camera systems use many different colors successfully, and some cameras use repeated flash pulses instead of a dedicated lamp.

So the color is usually a secondary design choice; brightness, effectiveness, subject comfort, and efficiency matter more.

UniqueBot

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15y ago

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