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Red lights and dark adaptation for eyes


JOC

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I've read a lot recently about the need to have eyes adapted to dark viewing, the use of red lights and the speed with which a which a white light can destroy the eye's adaptation.  It all makes sound sense.  It also makes me feel that I could never visit a star party even thought they sound interesting and fun enterprises as I would inevitably mess things up and would be terrified of the reaction when I did so.  However, I wear spectacles regularly and it did make me wonder if the solution to this eye adaptation would be the use of red glasses or even red contact lenses.  I can't be the first person to think of this, so why are they not a practical solution?

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The purpose of white light filtration,  is to protect observers,  and especially Star Party guests who are using their equipment to capture precious data from the sky.   This can be photographing deep sky objects, comets,  or any other body that demands long exposures.  The ingress of white light can ruin an exposure runs.  So it is imperative that  everyone at such a gathering, obeys the ruling on white light. People use red torches to find their way around in the dark. The use of car lights are also severely frowned on.   Laptop screens can also be intrusive,  so red screening is advised.  Red spectacles can help in preserving your eye sensitivity,    but my message to get across the need to protect everyone on site as best we can by outlawing white light as best we can. It's no use having red specs,  if you are wandering around with a  white flashlight. :icon_biggrin:

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Ah, so the instruments themselves and electronic data gatherers are sensitive to white light - that would explain things.  Well that was just a 'I wonder why' question and they do say there is no such thing as a silly question..........

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Be a little careful when it comes to a red light. The idea gets across that if it is red then all is fine. And basically it is not. One of the most "painful" times I had was some idiot assuming that their red headlight shining in your face was OK and not a problem because it was red.

The "red" (according to one artical I read) needs to be of a certain wavelength or longer, so in effect one red is OK(ish) another may not be. Then comes the general brightness - consider why a red light would not activate the colour receptors of the eye but a blue or green one does. The answer is a red one does activate the colour receptors just as a blue or green one does.

There is a difference between you using a red light to find thngs you want to locate amongst your equipment and generally shining the light everywhere. Hence a torch is easier, you can stick it in a pocket if all else fails.

I think about a year back someone took an image of a star party. Heard of "light pollution" ? Well this star party had light pollution in the red bit of the spectrum, it was everywhere. It wasn't just a few bits at ground level, it was a classic dome of light pollution over the star party.

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Barkis - I'm sure that's very true.  Don't worry, if I don't think I am capable of behaving like a non-silly person I won't ever put myself in a situation where I could be accused of being one!!  In fact I'd be horrified to find out I'd wrecked someone else's evening because of something I'd over-looked due to inexperience.  I just loved the notion that I'd read about on here that groups of interested people, get together and spend quiet evenings sitting together in a dark field with these marvellous instruments watching the stars and that someone has seen fit to call the whole shebang a 'star party', which I think is a lovely name for them.  Then I started to read about the white light's issues and, as a regular camper myself, I began to think about the amount of preparation that everyone must make to ensure no light problems.  Then I started to reason that any gathering of astronomers must have similar issues.  I concluded that, much as it would be nice to chat to someone about what I was seeing, I don't think I'd have the courage to go to an astronomy event as there is clearly a whole lot more etiquette which applies to such gatherings than I would have ever imagined.  However, it will still be interesting to follow the threads on SGL the next time one occurs.

In fact I find the idea that the instruments that folks use to capture their data are white light sensitive as making a whole lot of sense.  I am an advanced analytical chemist by qualification and training and many analytical instruments gain their sensitivity by sampling wavelengths of light against a black background rather than a white one.  What I didn't expect was that people would be able to deploy such 'technology' with what I anticipate is a concurrent need for decent electricity supply on a camp site with just, I assume, batteries for power.  However, a red lens in spectacles might help my own situation when my parents wander out to view what I am looking at resplendent with their bright white torches.

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My setup requires a (roughly) 5 amp supply. This runs mount, cameras and dew control. I then also need a supply for the laptop :) most campsites supply 18amp to each pitch.

Dont worry about star party etiquette to much, it isn't that bad. 

It boils down to...

No white light at all, and as little red light as possible.

Be courteous at night and in the morning to those that may be asleep. 

Dont touch other people's stuff without asking - you don't know what they may be doing.

Bring Jaffa Cakes

Be nice 

Star parties are great, the amount of stuff you learn just by sitting around and talking is amazing. The rules are easy to follow and are no more than you'd do to protect your own night vision in your garden (neighbors think your nuts wearing the eye patch).

Ant

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I'm not worried, and why have you got the notion I think you are silly?  You've put that notion into your own head.
I merely tried to inform you about the displaying of light at a meeting of astronomers intent on either observing, or imaging the night sky 
residents, and by that I mean the very distant and faint Galaxies and Nebulae that modern Instruments and CCD cameras are very capable of recording in great detail.
Somebody either accidentally, or deliberately flooding the site with white light, being the lights of a vehicle, a computer screen, or a an unfiltered torch,
could impinge on the  sensor of  a CCD camera, and ruin an exposure that may have been active for 15 minutes. That is not going to please the guy taking the exposures.
My response to you post, was to try and enlighten you, not try to embarrass you, that would put my job here in jeopardy. 
SGL holds Star Parties at a venue that is not a million miles from where you live, which I believe is Essex, so if you want to experience that kind of event, 
you will have an opportunity to book a residence on the site, either using your own tent, or Motor Home, or Caravan, or whatever you have.
I think to some extent, we have been at cross purposes on this topic, I'm sure it will be a lot clearer to you by the end of it
 


 

 

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Barkis - no problems here.  I had already read the threads on red light etiquette with great interest and had read further on the physiology of the eyes to try and work out what was worth doing to improve my own experience.  However, what I didn't gain from them was that the red light not only protected the human eyes, but also the instrument 'eyes', hence there must be a reason why red lenses for human viewers weren't the answer, but I hadn't found it in my reading - hence the question in the OP.  In fact I think that there is more reason to be careful if people use light sensitive equipment than if we are just talking human eyes. 

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Have you ever wondered what astronomers did before electric lights were invented? A candle or lantern could hamper dark adaptation as much as an LED. William Herschel got round it by dictating observations to his sister who sat inside a lit hut. A later astronomer (whose name escapes me) used the smouldering end of a cigar as his red light.

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acey, that's an interesting point.  I wonder how long it was before astronomers had linked red lights to being less problematical than white ones.  I wonder if the early astronomers ever used red glasses in oil lamps?  My gran worked on the railways and they used to have railway oil lamps that had sheets of red and green glass that they slid in place to change the colour of their lamps for signalling purposes

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Your question is a great one :)

The real answer is, if you can get by without ANY lights, then you will see more. And so will everybody else.

However in reality we need to check star charts, use hand controllers, view laptop screens etc etc. There does tend to be quite a lot of flashing LEDs, controllers, laptop screens and torches at star parties.

Last Kelling autumn party somebody came around with what can only be described as a red floodlight. They were casting sharp shadows with the darned thing, ruining everyone's dark adaptation in the process. Red LED headlights also work well for the person using them, but are a royal pain in the posterior for everybody else as the light is directly in your eyes.

A lot can be done on a personal level to make your experience better, and by extension for everybody else. Things like;

1. Cover LEDs on mounts, dew controllers, cameras etc with a couple of layers of red insulation tape to mute them, especially green/yellow/white/blue LEDs. Phones, ipads etc all need considering.

2. Adjust if possible the brightness of your hand controller to its lowest setting.

3. Turn laptop screens down to their lowest brightness settings and use a proper cover for them, like this one - https://www.firstlightoptics.com/misc/starsharp-red-filter-for-laptop-screens.html (really excellent!)

4. Prepare in daylight. Even if it is cloudy, in case it clears. Put things in easily accessible places, where you can find and use them without needing to light them up. Familiarisation with things like eyepieces, filters, barlows etc in the daytime really helps when using them by feel at night.

5. Consider a separate enclosed tent/shed to keep eyepieces or imaging laptop in. This can be lit with a dull red light where the bulb is overhead and unlikely to shine in your face. Most experienced observers have somewhere like this they can go to check charts/swap EP's, control their equipment from.

6. When determining what objects to view, save planets and bright stars to the end of the session, they will spoil night vision too!

It is entirely  possible to perform quite complex actions in the pitch black. Years ago I used to hand load film canisters with off the roll film, and this had to be done in complete darkness, being familiar with the equipment is the key.

I would imagine that every one of us who has been to a star party has been guilty of inadvertently or accidentally ruining somebody else's dark adaptation, I know I have, lots of times. Nobody has killed me, yet! To be frank, I have learnt through the frowns and grumbles of others what is acceptable and what is annoying :p

I suppose it boils down to preparation in the end. Experienced observers and imagers will have everything set up, ready and waiting to go, and when the skies clear they can quietly and efficiently get on with the business of astronomy.  It can be frustrating to go to a dark site, get all set up like that, only to find yourself next to somebody who didn't take the time to get ready and then stumbles around flashing lights everywhere looking for bits and bobs :p

Another consideration at star parties is for laptop users still to cover their screens with red filter even if they are inside the tent. A tent glowing blue or green stands out like a beacon in the dark.

Again, the less local light there is, the more of the universe you will see.

Hope that helps a bit :)

Tim

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Actually it seems that JOC's original question is not so far off the mark.

Dark adapter googles have apparently been used by astronomers and meteorologists and were invented in 1916 by a German doctor, Wilhelm Trendelenburg. See: https://en.wikipedia.org/wiki/Dark_adaptor_goggles  If I can find a suitable pair of red goggles, I might just give it a try! This said, I don't know anyone who admits to using red goggles - perhaps it's something best done in private?

Red goggles also used to be used by doctors to help prepare for night vision or Scotopic vision necessary for fluoroscopic examinations: https://www.orau.org/ptp/collection/Radiology/goggles.htm  shows a pair of goggles from the 1940s.

http://www.usscasimirpulaski.com/virtualmuseum.htm  shows red goggles used by certain key personnel on a US submarine during the Cold War era to preserve night vision under normal lighting conditions.

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Putaendo Patrick, that's really interesting and certainly provides the sort of answer I had hoped to find.  Yes, I completely 'get' the points that folks have made about needing to accommodate and protect instruments which can be affected, but for the lone person in their back garden who doesn't have this type of kit, but who does have white light pollution from other sources (my own situation) that they can't control, then maybe red lenses (even red contacts if you don't have kids to scare) might help?  

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And here they are, folks! The genuine Orion Astrogoggles, now on sale at half-price only $5.00. Several satisfied customers.

http://www.telescope.com/Orion-AstroGoggles/p/99998.uts?keyword=astrogoggles

Red goggles were also found to reduce violence in chickens. Millions of pairs were sold each year in the US, I'm not joking!

320px-Eye_Glasses_For_Chickens.png

180412013_vintage-chicken-rooster-red-ey

see: http://unusual.info/2013/11/12/spectacles-for-chicken-safety/

 

 

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Putaendo Patrick, so..... Orion star goggles eh?  There were also 20 reviews from satisfied people too.  So it seems that a set of red lenses may be of use, so much so that someone even made a product around the idea,  I love it!  Brilliant detective work 'Sherlock'. 

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No one has mentioned cars?
Do they need all their bulbs covered?  with most modern cars,   4-ways are linked to the remote! how on earth do you stop the flashers when locking the car ( or do you have to trust everyone and leave the cars  open - there is some very expensive gear laying about otherwise ? )

When I observe from my Dob-Tent! I see nothing inside the tent, pitch black, all done by feel, but away from the house on a perfect night, there is so much Starlight, who needs a torch!
 

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