Making the chart table light red

[firstascent2002]

The chart table flexi light has lost its red cover on "the hustler". Does anyone know what the red stuff that people secure over stage lights to give a red glow is called? It's a sort of crinkly acrilic. Hard to find a supplier when you don't know what its called!

thanks
J

 

[l'escargot]

Try somewhere that sells disco equipment, they are usually just called coloured filters. This place does them here

 

[[2574]]

i must admit to using SWMBO's red nail varnish on the light glass cover - works a treat!

 

[Clyde_Wanderer]

Why not try Jessops for a red camera filter, or thr ones used in photographic printing enlargers.

 

[shmoo]

this is the real stuff http://www.stagebeat.co.uk/P/2733/COLOUR+FILTERS+GEL+SHEETS
but local craft shop may sell cheaper stuff for makeing "stained glass" windows.

 

[tangofour]

Just replace the bulb with a red LED

 

[billcowan]

I read somewhere that scientific tests show that the redness of the light has nothing to do with preservation of your night vision, and that its just the dimness that counts.

Not to mention that a red light can make detail on paper charts just disappear

So just fit a dimmer bulb.

 

[shmoo]

[ QUOTE ]


Not to mention that a red light can make detail on paper charts just disappear


[/ QUOTE ]

but note
[ QUOTE ]

...on the night of the accident, as was his normal practice, he had removed the red screen and allowed the unfiltered white light to illuminate the chart table. This would have adversely affected both sic his night vision...

Report on the investigation of the loss of the sailing yacht Ouzo MAIB


[/ QUOTE ]
We run with red lights everywhere below at night and it really helps. The only detail on admiralty charts that disapears is the red sector of mutlisectored lights. I can live without that.

(edited for typo)

 

[shmoo]

Its worth rereading the whole of the section on night vision and dark apaption and white light in the Ouzo report http://www.maib.gov.uk/publications/investigation_reports/2007/ouzo.cfm

MAIB had the Institute of Ophthalmology contribute a statement on the issue.
Round about page 23/24

 

[john_morris_uk]

[ QUOTE ]
Quote:
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...on the night of the accident, as was his normal practice, he had removed the red screen and allowed the unfiltered white light to illuminate the chart table. This would have adversely affected both sic his night vision...

Report on the investigation of the loss of the sailing yacht Ouzo MAIB



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[/ QUOTE ] Even professionals can preserve myths...

 

[shmoo]

[ QUOTE ]

Even professionals can preserve myths...


[/ QUOTE ]

Do you include Institute of Ophthalmology? For it was they who contributed the relavant statement in the report.

 

[LadyInBed]

You can buy decorative paint for glass in Art shops that work on bulbs.

 

[mel80]

[ QUOTE ]

Do you include Institute of Ophthalmology? For it was they who contributed the relavant statement in the report.

[/ QUOTE ]

Ah, but the institue of Ophthalmology statement says nothing about the wavelength of the light, and the report itself refers to the fact that he removed a filter, not that he was using white light. As far as I know, light intensity is the single most important factor affecting how quickly rhodopsin is broken down; an unfiltered light will be a lot brighter than a filtered one. Whilst it is true that rhodopsin is affected less by red light than other wavelengths, our vision over all is also a lot less sensitive to red light . In other words, we could see just as well with a low intensity white light than a brighter red one.

If I was installing a chart table light, I would have a white light with a dimmer switch.

 

[shmoo]

[ QUOTE ]

...and the report itself refers to the fact that he removed a filter, not that he was using white light.


[/ QUOTE ]
I am afraid it quite explicitly does:

Further investigation on this subject has also revealed that, to all intents and purposes, as soon as a person’s eyes are subjected to white light, their dark adaptation time starts again from zero. Therefore, the second officer’s and the lookout’s dark adaptation periods started from when they left the chartroom.
page 25

and

Advice on the fact that exposure to white light effectively sets the adaptation to night vision clock back to zero page 49

and as for not refering to wavelength (or colour as we simple folk call it)

he had removed the red screen and allowed the unfiltered white light to illuminate the chart table. page 25

It was a red filter he removed.

 

[AndrewF]

My navigating officer just colours the light bulb with a red marker pen. Works well and is cheaper easier than trying to remember to get bulbs of different colours.

 

[thalassa]

Indeed. If you remove the red filter on a lamp, the light level increases between 8 and 20 times. Ask anyone like me, who has spend a few thousand hours in a B&W darkroom...
A single white LED is more appropriate on the chart table.

 

[pampas]

Personally I have found that orange is the best light for me. Gives almost perfect conditions for chart work and none of the fittings are visible from the cockpit,so if anybody is down below all you get is a warm ,dull glow.

 

[whipper_snapper]

But I suspect that throughout they are confusing colour with intensity. It was a red filter that was removed but its effect was to make the light much brighter.

I don't know of any evidence that red light per se is better for preserving night vision, but would be very interested to learn more. At present I use a very dim white light for chart-work at night.

 

[Ruffles]

A while ago Brendan posted this link. Contains enough references to keep you busy for hours. At the end of the day I think it's personal preference. I have one of this bendy chart table lights with a twistable filter that makes a dim orange light. I'm happy I can see the chart anyway. And I've not knowingly missed anything on deck!

 

[Bejasus]

[ QUOTE ]
I have one of this bendy chart table lights with a twistable filter that makes a dim orange light.

[/ QUOTE ]

We have something similar but which can switch between a low wattage white and a pale blue light, which seems to reproduce detail pretty well.