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lengthy exposures are a liability, because of the distortion so often caused by reflected beat-waves.
‘‘I think we were using the most powerful telephoto lens ever used in Los Angeles. The Griffith Observatory telescope is of the refracting (lens) type, with a focal length of 16 feet 8 inches. The lens works at a fixed maximum aperture of 12 inches, giving us an effective working speed of /:16. With this relatively small aperture, am film which will cut exposures to the minimum is a big help.
‘'By way of comparisons, I might mention that the huge 200-inch mirror telescope now being built at Cal-Tech for use in the Palomar Observatory will work at a speed of /: 3.3 while the Schmidt scouting telescope already in use there works at /: 2.
“Our first tests were made on Agfa Superpan, using a K-3 filter, which happened to he the only one available at the time large enough for our purpose. With this combination, photographing the Los Angeles City Hall, over 8 miles from the telescope, our exposure was 1 /10 second at the telescope’s one aperture, /: 16. Using Agfa Infra-Red negative and a 29-F filter, our exposure was 2 seconds, of course at the same aperture. I have since gained access to a private telescope of equal power, hut of the reflecting or mirror type. This works at an effective aperture of /: 8, which should cut our exposures down to % second. With it I am planning to make further telephoto panoramas of the city, including. if the weather favors me, a panorama of the Fleet at anchor in San Pedro, more than 20 miles away.
“What is my purpose in all this? Well, it is not solely that of exercis
ing my astronomical hobby, nor even of getting strikingly unusual pictures for the Herald-Express. What 1 am hoping to do is to begin to arouse a telephotographic consciousness in the minds of Southern California’s hundreds of amateur astronomers. There is a really incredible number of these private backyard observatories in this territory. Some of them house commercial telescopes; far more house instruments home-made — even to lenses and mirrors — hy these enthusiastic amateur astronomers.
“But very few of these amateurs have discovered the possibility of harnessing photography to their hobby. And once the thrill of looking at the heavens through a telescope you have made yourself has worn off, you are in a mood to welcome something new.
“As it is, while much good, constructive visual observation is being done hy these amateurs, it is by no means as systematic and scientifically profitable as it could he. Quite a few worthwhile astronomicial discoveries have been made hy amateur astronomers; but there is always a chance for error in something new observed only visually.
“If these amateurs would fit photographic attachments to their telescopes, they would not merely have proof of their observations. They would learn that the camera can reveal stars too faint to he observed visually. And when they made new' discoveries, they would have the evidence in tangible form which could he analyzed hy professional astronomers, and would in all probability add more importantly to the sum total of our astronomical knowledge.”
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