Thread View: net.astro.expert
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Started by chris
Wed, 05 Jun 1985 23:17
Re: Eyepieces
Author: chris
Date: Wed, 05 Jun 1985 23:17
Date: Wed, 05 Jun 1985 23:17
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In article <2470@decwrl.UUCP>, liss@psyche.DEC (Frederick R. Liss 237-3649) writes: > today is the advertisements for telescope eyepieces. When I got my first > telescope there were only a few types of eyepieces. I'm not sure of the > spelling or the exact names, but I believe they were the Orthoscopic (?) > and Hyugens (?) eyepieces (correct me if I'm wrong) . Today I see adds > for Nagler, Wide Field, Plossl, and Kelner eyepieces. What you are seeing is a variation in the complexity of the construction of the lenses. The cheapest lenses (such as Huygens) are made with one or two simple lens. Orthoscopic, an expensive brand, is made of several lenses packed together. The newer lenses fill in the gap in between. The reasons for different lenses are several: 1. To offer the customer a variety of price ranges. 2. To offer different degrees of solution to the various problems associated with lenses. One problem is chromatism, or the tendency for the lense to act like a prism and break up the light of the image, particularly near the edges. Some types of lenses are limited in their focusing power. All the brands should come in a variety of magnifications and allow the option for a filter to be installed in the base of the eyepiece. Some lenses are better built (shock proof, etc.) but cost more. As far as lenses being matched to a particular type of telescope, I believe that eyepieces with wider fields are best used with shorter focal lengths. There is a maximum practical eyepiece magnification for a given telescope. The manual that comes with it should mention this. (E.g., a 60mm refractor shouldn't be used with anything smaller than a 12.5 mm eyepiece. ) An excellent source for information on telescopes is Edmund Scientific Co. in New Jersey. They sell everything associated with the hobby through a mail order catalog that they put out. - Christopher Salander Lockheed Space Systems Div. Silicon Valley
Re: Re: Eyepieces
Author: USENET Current Events
Date: Wed, 19 Jun 1985 16:24
Date: Wed, 19 Jun 1985 16:24
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*an interesting opinion!
Superresolution
Author: Charles Neveu
Date: Thu, 20 Jun 1985 15:29
Date: Thu, 20 Jun 1985 15:29
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Could someone send me some pointers to literature about a technique called superresolution? (sp?) I've been told that astronomers use it to determine the positions of stars to 1/100 pixel accuracies. Specifically, I'd like to know how it works, what kind of claims are made for it, and what other applications it has been used for. Thanks in Advance, Charles neveu@lll-crg
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