Outdoor TelescopesFirst we have to understand as to what do we mean by outdoor telescopes. An outdoor telescope is one that has to be Portable so that an observer takes it outside either in hills or plains for research works. It has to fit comfortably into the luggage compartment of a car and still leave plenty of room for camping gear etc. Secondly, it has to be light and manageable by one person, thirdly it should not take long to set it up or to dismantle it. Fourthly, the internal lenses should be self-adjustable to exterior lights and there should be enough light baffling so that it does not require a shroud. Last but not the least, the lines of an out door telescope has to be smooth and simple, so as to ensure that any friction or vibrations from sound or movement etc does not affect its performance for delivering good, clear and accurate images. There are 3 basic types of outdoor telescopes: 1. Refractors are long, thin telescopes that collect light through multi-element lenses. Known for sharp, detailed, contrast images, they are best for viewing the moon and planets. 2. Reflectors (Newtonian) collect light with a curved, concave mirror. Their large apertures allow them to serve up fine, highly resolved images of planets and deep-sky objects alike. These scopes are unsuitable for terrestrial (earthly) viewing as they produce an upside-down image and are designed exclusively for astronomy. 3. Catadioptrics or compound telescopes use both mirrors and lenses to collect and focus the incoming light. They sport very compact tubes, and give you great all-around performance. All telescopes collect and focus light. The most important feature of any telescope is its light gathering capability, or aperture (the diameter of the main lens or mirror, usually expressed in inches or millimeters) that determines how much you will be able to see. The more light gathered, the more you'll see. Large apertures will yield sharper images only when that area has stable atmospheric conditions (primarily air turbulence) and promotes excellent "seeing". Most of the time in most of the world, seeing is moderate to poor. Magnification is not the most important consideration when choosing a telescope. Excessive magnification blurs the already blurry image, mostly by amplifying the effects of air turbulence. In practice, the brightest and sharpest images are obtained from much lower powers of a telescope. The telescope's power or magnification is adjusted by changing eyepieces. Basically, we should have ideally three no of eyepieces—one low, one medium and one high magnification. For a larger image, use an eyepiece with a larger number. For close-ups, use a smaller number. We can buy other eyepieces to increase the versatility of our telescope. Apart from the above we should also know about telescope mounts. Telescopes come on three basic mounts: Altazimuth, Dobsonian, or Equatorial. - Altazimuth is the simplest type of mount, providing up down, left-right motions and is recommended for casual stargazing and terrestrial viewing. - Dobsonian mount is a boxy altaz-type mount that sits close to the ground and was designed for easy maneuvering of large reflectors. - Equatorial mounts are a bit more complicated (and more expensive) than the altazimuth mounts and are designed solely for astronomical viewing. They are tilted, with one axis aligned on the celestial pole. These types of mounts allow the user to track or follow the motion of celestial objects through the sky with a single manual hand control, or automatically with a motor drive therefore giving great convenience. Most telescopes come with a sturdy mount and a tripod to bring the eyepiece up to eye level. Finally, the two most important questions are what do you want to see and where will you be observing it from? We should look at all the different types of telescopes, and in doing so; some of the above-mentioned information will help us influence our choice and decision for selecting suitable outdoor telescopes as per our requirements. |
Telescope-Information.com
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