The major emission lines of artifical light pollution: The most important lines are from ionized Hydrogen (H-alpha and H-beta) and The most important emission lines from nebulas are shown in green.Which are used in nearly all streetlights. The artifical light pollution is dominated by see mercury (Hg) and sodium (Na), The most important artifical emission lines are shown in orange.Photographic filters: The grey line in the background shows the sensitivity of a typical CCD sensor.You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at The maximum is at ~510nm and drops to longerĪnd shorter wavelengths. Visual filters: The grey line in the background shows the relative sensitivity of the human eye at night.The red line shows the transmission of the filter.The transmission in % is plotted on the vertical axis.The famous "H-Alpha" emission line of hydrogen. 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. The horizontal axis is the Wavelength in Nanometers (nm).More information about the visual Astronomik filters With EOS Clip Filter even in extreme light polluted areas photography with DSLR cameras becomes possible.Without a filter the eye is hardly able to discover the low contrasts of H-alpha regions. On the other hand h-beta filters often decide about seeing or not seeing an object. In the whole sky, there are few objects that benefit from the use of this filter in visual observation.Due to the high optical quality of the Astronomik H-beta filter substrate you will see the same needle-sharp stars as you would from your regular telescope. Smaller instruments do not gather enough light for meaningful and satisfying astronomical work. This filter should be used on telescopes with a diameter of 8 " (20cm) or larger. The Astronomik H-beta filter will allow you to view large objects, in the whole field of view of the eyepiece, even when using wide-angle eyepieces - not only in the center of the eyepiece. Transmission losses and chromatic distortions, which arise with other filters, are only apparent with the Astronomik filters when extremely fast aperture ratios of 1:3 and higher are used. The range of application extends from 1:3.5 to 1:15. The optimal aperture ratio for the use of the filter is 1:4,5 to 1:6. By the use of the Astronomik H-beta filter, the contrast is increased so strongly, that even the observation of the Horse Head Nebulae with telescopes of 10" - 12" reaches the realm of the possible. It lets the light of the H-beta emission line pass nearly unhindered and blocks the remaining spectral range to the extent that the eye is dark adapted. Later ones only have a batch sample tested.Astronomik H-beta Filter Transmission CurveĬlick the image for full resolution The Astronomik H-beta is a filter for visual observation, in particular with instruments of larger aperture. The first 3 were all individually tested. I haven't seen that same deterioration in the later ones. The Livermore CA ones are all failing due to oxidation by now. In tests, the 2005-2012 filters had the narrowest bandwidths and the 2018+ filters have the highest transmissions. The 5th generation (actually more than the 5th generation-maybe the 9th-but called "Generation 3") come in a translucent plastic box with rounded corners (Rancho Cordova, CA 2016-now for the UHC and 2018-now for the O-III) The 4th generation, for a very brief period, were Chinese-made and came in squarish boxes. The 3rd generation came in the same clear/black boxes and looked the same but you could see the coatings didn't extend quite to the edge of the filter. 2001-2012 (there were more than one version in this time) Some were unlabeled, some were labeled, but all had a slightly knurled lip. The 2nd generation came in the blue boxes, and a clear version of the same box with a snap-shut and a black bottom. 1979-2001 They sold the seconds as "standard" and the decent ones as "premium". The first Lumicon filters had no labels on the filter, had rounded edges on the filter housing, and came in small square transparent blue boxes. How can you tell which Gen Lumicon filter you own ?Īre there visual distinguishing marks for each generation ?
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