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Re: First Successful Submarine- not

As a Navy Photographer, and sometime seaman while so engaged, I know a little about light, though not the blue light signal methods used during the WTBS. Red light is used at night on ships where vision is needed, but night vision must be protected. The retina can see red light better than other colors, without compromising night vision when going out on deck. By the same token, blackout curtains are used where the transition takes place, so the red light is not seen from other ships. This sensitivity to red light accounts for the ease of seeing a cigarette's glow at sea. If you've made a night landing aboard an airplane, you might have noticed the first approach lights to the runway are red, while blue lights are used as you get to the end of the runway. Color photographic film is typically balanced for tungsten filament film lights. When used outdoors, a salmon colored filter is placed over the lens, to remove some blue from sunlight. The same color filter material is placed over windows where daylight comes into an artificially lit set. Conversely, if silver halogen bulbs, which are balanced for daylight use, are used indoors, the filter is placed over the bulb, to balance the light to the film. I hope this is not too far afield from the subject. Stan

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sjgi1t76
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