Quick Question about red light

[tibbz2]

Hey guys,

I have a red star map torch (Carson) and was wondering, because it is rather bright, if that has any effect on your night vision? I'm guessing it doesn't, but I want to make sure.

Thanks

[Naemeth]

Hey guys,

I have a red star map torch (Carson) and was wondering, because it is rather bright, if that has any effect on your night vision? I'm guessing it doesn't, but I want to make sure.

Thanks

Does it look bright at night or during the day? We're most sensitive to red during the day, and green at night.

HTH

[Moonshane]

the way I look at light and observing is you should get a light which gives red light that is as dim as you can get away with. ever ridden behind a car with the fog light on when not needed or brake lights stuck on? the intensity is as important (almost) as the wavelength.

[tibbz2]

When I was using it last month it seemed rather bright as it is just a red LED... It's made for stargazing so I guess it can't be too bad?

[acey]

If a red light is too bright then it will damage your dark adaptation. Ideally a red light should be as dim as you can tolerate, and should only have wavelengths at the reddest end of the spectrum. Red nail varnish, paint, plastic etc often transmit shorter wavelengths that make the light look orange or purplish once you're dark adapted - these are to be avoided. Red LEDs are good if they're not too bright, but even they emit some light at less desirable shorter wavelengths. The best way is to use a white light with a filter that blocks everything except deepest red. A dim light makes map-reading difficult - use a magnifying glass rather than a brighter light.

The test is to look at a very faint DSO with well adapted eyesight, then do some note-taking with the light, then look at the DSO again. If all you can see is an after-image of the light, then it's too bright. Ideally you want the DSO to look the same as when you looked previously.

If you're LED is too bright then use partially depleted batteries.

[scarp15]

A torch with adjustable brightness such as the Skywatcher Duel LED, which comes with a neck cord (available from FLO) would be a good option. I also use a headtorch with one red LED (petzl elite) which is quite dim and as acey has commented, combine using this with a magnifying glass for reading charts.

I have some of the cheaper red torches and head light, which my daughter plus her friends will use if attending a star party. They can be quite annoying as they can glare, if pointed in your face and dazzle you somewhat, momentarily diminishing your night vision. As this is just occasional, it is worth it since they do get involved.