Re: suggestions for red light

brucegooglegroups <brucegooglegroups@xxxxxxxxxxx> wrote in
news:6e07bcdf-2341-441d-99f7-588e7436c2b4@xxxxxxxxxxxxxxxxxxxxxxxxxxxx:

I have an Orion Dual beam flash light, but it doesn't give off a lot
of light for reading maps.
Suggestions for a stronger red light?
Bruce

There are two problems here: How do you read a chart under light
polluted skies where you are not fully light adapted? How do you read a
chart under those rural mag 6 dark skies that you ocassionally drive to?
How to you get the right light for both conditions out of one
flashlight.

Dealing with the second question - reading a chart under mag 6.0 skies
when you are fully light adapted and to re-enforce other comments in the
thread - dimmer - not brighter - is the way to go. The dimness of the
light is more important than its color.

Having recently lost and replaced my 2004 Rigel Systems I dual light
flashlight with the more compact 2007 Rigel Systems II mini-dual (that
Orion also sells), I had to go through this again.

http://www.company7.com/rigel/products/skylitemini.html

(I recommend the square dual mini shown in the picture, not the round
Model I, also shown in the picture. The square model II mini is much
better than the old model I. The square model is the same as Orion
sells. They buy from Rigel.)

The Rigel Systems II dual mini-flashlight has an alternate red and a
white LED. Looking at the red LED through some diffraction film, the
newer LED in the Model II mini has very little non-red light in it. I
decided that using the Rosculux gels screens to trim any non-red light
coming out of the LED was not necessary.

But I decided to add the gel filters over the red LED anyway, as
described below.

You can get enough Roscolux gel to adapt an RS Model II dual mini from
any theatrical supply house. Look in the phone book under "theatrical
supplies." Just buy or get them to give you a Roscolux sampler - which
can also be had from Amazon.

http://www.amazon.com/Roscolux-Swatch-Sampler-Almost-
Filter/dp/B0002ER2YG

In prior discussions in this newsgroups on the right cut-off filters to
use, the recommended cut-off filters were Roscolux 120 red and 83 blue.
The 120 red cut-offs of the red side of the specturm, the 83 blue cuts
off the blue side of the spectrum, leaving a very dim monochromatic red
light.

The RS II mini dual's brightness range over the red LED - in particular
at its minimum setting - was just too bright for use under a very good
mag 6.0 dark sky. I decided to use the Roscolux cut-off gels to make
full range the mini-dual more dark vision friendly.

The RS II mini dual easily comes apart. You can cut two simple small
rectangles from blue and red Roscolux sampler filters that can be proped
loose in an arch over the top of the red LED. The rectangles of red and
blue gel will stay in place when your slide the RS II mini dual assembly
back into its housing. There is no need to glue or affix them in the
housing.

Adding the filters over the red LED yields a good brightness response
range for reading charts in very dim light while maintaining dark
adapated eyesight under excellent mag 6.0 dark skies.

Turning to the first question - reading a chart under light-polluted
skies where you are _not_ dark adapted - I also find the red LED in the
RS Model II to be a little too dim.

I left the white LED in the RS II mini dual unobstructed and only use
the white light for emergency light and dropped-object ground checks.

But, you can also put just one layer of the red Roscolux gel ***
rectangle over the white light LED and get a passable "brighter" red
light for reading charts under light polluted skies.

The Rigel Systems dual mini II also had another minor drawback for which
I did a minor after-market alteration. The LED-battery assembly rattles
around inside the flashlight housing. It's a minor nuisance but of more
of a concern when you drop and kick the flashlight across the ground -
like I seem to still do once every other observing session. I decided
the probability of the of-the-shelf RS dual mini II surviving a full
season wasn't very good.

I bought a 3 x 2 inch square of dual velcro. A small rectangle of the
smooth side of the velcro was put inside the housing. This takes up the
free space inside the housing and the battery assembly no longer rattles
around inside the housing. When dropped, the whole assembly seems more
"solid".

The final end-user modification that I made to the RS II dual-mini was
to take a square of the fuzzy part of the sticky velcro patch and put it
on the outside of the housing - essentially covering the Rigel label.

The purpose of that modification was so the dual-mini can be quickly
attached to either a headband or to an exercise wrist strap and used as
either a headlamp or a Star-Trek NG type palm beacon.

Almost all of the time, you just hang the dual mini flashlight around
your neck on the provided neck-strap. But there times, when having a
"hands-free" light beaming right on your work area is a big help, i.e.
when you are adjusting your Meade mount alignment with a wrench, are
trying to screw in a dropped screw out of an camera adapter with a mini-
screwdriver, or are adding a camera assembly to your scope while holding
on to the assembly with both hands.

Hope that helps.

- Canopus56

P.S. - I still have my "bright red flashlight" - an original basic
flashlight covered with roscolux gel for use as a brighter light for
chart reading. With the RS II dual-mini modifications described above,
it pretty much lives in the truck. I don't pull it out anymore.



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