[Silverwolf]

I've heard a few second-hand cases that owl photographers often use a red light so that their camera can auto focus on their targets at night time, when auto focus (and even manual focus) is pretty much useless. The logic is apparently that red is good for exaggerating contrast in low-light which most cameras use to auto focus.

Any ideas if this is true? I would rather not have to point a super bright white beam at a nocturnal critter to get focus on it.

[Farnboro John]

It is sort of true.... If you use an off-camera flash such as a Canon Speedlite, it has an "AF-assist" light below the main flash, which lights up when you attempt to auto-focus. Frankly its not very powerful, but it is red. It projects either lines or cross-hatching in red which gives the camera a contrasting pattern on the target surface to aid focus. It's often ineffective (a) on moving things) (b) on heavily textured things such as deeply crevassed bark and (c) at any distance useful to a wildlife photographer! Within its powers it works.

The real advantage of red light to a wildlife photographer is that at reasonable (useful) intensity it shouldn't frighten most of the animals, many of which will see in monochrome. It's still a good idea to use the least power practicable, not least because at a lot less than max chat (e.g. second frame etc. if firing continuously) your flash may not overcome the redness.

Having said that some people swear by green rather than red light, but the same principles will apply in relation to the beasts themselves.

Hope this helps. There was some discussion of red lights etc under night vision recently in the Equipment section.

Cheers

John

PS: if you are on a night drive or similar and will have to react quickly, just use white light to aid your flash, its much the most effective not least for your own eyesight. LEDs give quite a decent quality of white light, whereas older torches/spotlights are often a bit yellowy.

[Zackiedawg]

A secondary logic and reason for using red light when photographing at night is not necessarily to do with the camera or autofocusing, but to not spoiling your own night vision adjustment to your eye. Using a dimmer red light to help see camera controls or settings in very dark conditions will prevent a bright white light from blowing your dark-adjusted eyes...for the sake of spotting a distant animal or bird at night, this would be very useful - the same reason many astro-photographers and telescope enthusiasts use red lights for reading maps, controls, etc in dark sky night environments.

[Holter38]

Originally Posted by Zackiedawg

A secondary logic and reason for using red light when photographing at night is not necessarily to do with the camera or autofocusing, but to not spoiling your own night vision adjustment to your eye. Using a dimmer red light to help see camera controls or settings in very dark conditions will prevent a bright white light from blowing your dark-adjusted eyes...for the sake of spotting a distant animal or bird at night, this would be very useful - the same reason many astro-photographers and telescope enthusiasts use red lights for reading maps, controls, etc in dark sky night environments.

That explains it further.