Pat and I are taking a course on viewing the Night Sky. A 12 lecture series that will cover recognizing the stars and constellations in the night sky.
We have been issued a device which many would refer to as a sky chart, but is properly called a Planisphere. It has a dial that allows you to set the time and date and if you aim it correctly you can pick out every major constellation. You have to go out on a clear dark night to appreciate the views.
If you look at the picture of the Planisphere it says you must use a red filtered light to read the chart while checking the star.
Now why a red filtered light? Apparently when you are in the dark if you see any light your pupils in the eyes dilate. Except for red light.
If you watch movies about submarines they all switch to red light in the control room so the captain can look into the scope and see the enemy. If you are out at night looking at the sky and want to check the chart and you use a normal flashlight you blind yourself for several minutes.
With this off-hand reference in the course that we needed a red lens flashlight it took me on a must buy adventure.
Seems trivial but even on E Bay I was looking at $30 for a proper flashlight. I went to the ultimate of source in the valley, Canadian Tire, and while they did have a red lens flashlight for night vision, it was $40.
So I am thinking how hard can this be. I must have a dozen flashlights at home all I need is a red lens. Where can I find red clear plastic with optical qualities? In the automotive section I find replacement red lenses for trailer tailights that have been broken. 4 inch lens but only $2
I bring it home and grind it down to the right diameter to fit one of my flashlights and lo and behold I have a red lens flashlight.
As they say “If women don’t find you handsome they better find you handy” It is great to be both.
December 8, 2012
rbellis11
Views From Paradise 
4 responses to “Red Lens Flashlight”
Lois Hawkins
December 8th, 2012 at 10:35
so now you have to plot the space station too when it is in your night time sky; it was so impressive to follow it when it was being constructed and to see it grow; haven’t followed it since i’ve been in Edmonton!
Janine
December 9th, 2012 at 11:20
Now this is a course I would like to borrow. Recently in the southern hemisphere on clear nights and had no clue where the southern cross was… or what it looked like in relation to size and number of stars. Need to fix that!
James Ellis
December 17th, 2012 at 09:15
I think you are overthinking the red lens thing. When I was doing astral observations in university all we did was to take a sheet of red translucent film or paper and cover over the usual white lens. Voila – red light. (There’s also the other trick that Robbie Jr. taught me about keeping one eye closed while using a light source like this so as to not disturb the dark adaption in that eye.)
rbellis11
December 17th, 2012 at 19:11
That only works IF you have some red translucent film. That actually was my first idea but no where in our house did we have red translucent film. Apparently no all homes keep a supply of this. So when I was out looking for a solution I did look for this in either packaging or waste material but to no avail. The trailer taillight lens replacement was an inspired idea and fortunately I have the tools to work it. Band saw to cut the rough shape and vertical belt sander to do the final shaping. For $2 I have a professional looking red flashlight as versus spending $10 for a sheet of red plastic film and using an elastic band to hold it on.
My solution was neater.