I agree with Kim here, either green or red works the key is brightness. Using the Grim I don't ever get truly dark adapted, seems if you can read the computer screen it is probably to bright. There does seem to be faster recovery of dark adaption when red light is used. I used the grim with sun reading glasses once, because I brought the wrong ones, it did seem to help with computer screen brightness. SPOC is not a great place for dark adaption, but it is great location for public star parties.
Reading star charts seems to also require a certain brightness that may not help dark adaption. Goto systems help with this. I imagine the Navy nowadays relies on radar and any lookout either uses night vision equipment or is not exposed to much ambient light while using binoculars. I use a flashlight with a red photo filter taped over the lens; the filter
is covered with tape except for a silt, so that it's pretty dim. It works fine for me. Unfortunately, my computer screen tends to reduce my night vision, even when I have it dimmed with a red tint that's available with a couple of astronomy programs. But I feel sure red light is the best way to preserve night vision. -- Joe
--- On Sun, 8/29/10, Jay Eads <jayleads@gmail.com> wrote:
From: Jay Eads <jayleads@gmail.com> Subject: [Utah-astronomy] Red Light Myth To: utah-astronomy@mailman.xmission.com Date: Sunday, August 29, 2010, 3:46 PM
While listening to some 365 days of Astronomy PodCasts while grading today, I listened to one on Red Light and Night Vision. The author has the podcast as an article on her website located at http://www.alicesastroinfo.com/. She sites a US Navy study from the 1980's to lead off the article:
"Red light has been used because it is well established that subsequent dark adaptation is faster than with any other color. However, the magnitude of this advantage depends on the intensity of the adapting light. ⦠The measure that has typically been used to show this phenomenon is the time required to detect pinpoints of light at absolute scotopic thresholdâthat is, the individualâs maximum sensitivity. Although this is undoubtedly of great importance at times, it is probably true that in most practical situations the observer is required to operate at something less than maximum sensitivity and to detect targets quite different from spots of light."
Alice further quotes a website located here on the myth of the Red light: http://stlplaces.com/night_vision_red_myth/
"Experimentation shows a L.E.D. with a peek around 700nm seems to work best (perceived as a deep red). Note that red may be fatiguing to the eyes."
Alice also states that based on the US Navy's stud, one must be fully dark adapted for a red light to benefit and that using a red light source helps "but only if youâre going stargazing in an extremely dark place. If youâre stargazing from within a city, you will likely never be somewhere that dark."
I invite anyone to look at the sites, they are interesting I think. So what color light do you use when you observe in your backyard? Is it red, is it white or something else? What light do you use in the field if you need one? Does using a red light really help at a site like SPOC or a backyard where there is so much white light coming into the field from the surrounding neighborhood? Can such sites truly allow for full dark adaptation? I have my opinion but would like to see what others both do and what their opinions are._______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
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