StarWatch for the greater Lehigh Valley
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OCTOBER  2018

OCTOBER STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 10 p.m. EDT:   NORTH | EAST | SOUTH | WEST | ZENITH

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1155    OCTOBER 7, 2018:   Thinking about a Telescope this Christmas?
We are 11 weeks away from Christmas, and if you are considering buying a telescope for under the tree, now is the time to start thinking about that purchase. Unfortunately, most people wait to the last moment; and so as a result, they are rushed in their decision, pay too much money, and get frustration in return. If a manufacturer hypes the power that a telescope can attain as the chief reason for purchasing the scope, stay away from that item like itís poison ivy. Iím sorry to say that scopes sold at K-Mart, Walmart, or for that matter at any large retail outlet are a joke. For a while, QVC was hyping telescopes for about $100 per unit, and they were absolutely atrocious. Here is the bottom line. If you are unwilling to commit a minimum of about $500 to purchase a scope with a steady mounting (support) system, good optics, and at least two quality eyepieces, buy a decent pair of binoculars instead. Most smaller versions are light in weight, ergonomically designed, and they are immediately ready for use. In all cases you will see the image right-side up, over a wide field of view, and be able to use them during the day, as well as at night to look at awe-inspiring starscapes. My suggestion would be to purchase binoculars that produce a magnification of eight power with a 42mm light gathering objective, or an 8x42 pair. Seven by 50s (7x50) are generally considered best for viewing the night sky, but they are bigger, heavier to hold, and only achieve their full potential in dark, rural locales. Youíll probably spend about $150 for a nice pair, and if you donít drop them or allow them to fall into the swimming pool, youíll use them for the rest of your life. All telescopes are a compromise in one way or another, but all experts agree that telescopes are not built strictly for magnification. The most important aspect of a telescope is its ability to gather light and to bring that light to a comfortable, sharp focus. The eye, acting as the receptor of the light being gathered by the lens or mirror, is essentially enlarged to the diameter of the light-gathering mirror or lens of the telescope. Telescopes also need to produce crisp, vivid (high contrast) images of what the observer is trying to view. This requires optics that meet the criteria for generating astronomically acceptable images. When a manufacturer chooses quality over an avalanche of profit, superior images can be attained. The observer can easily see details on the moon, planets, and other objects in the sky. Telescopes also need to produce acceptable fields of view, so that the object under scrutiny can be seen in its entirety. Here is where a quality, wide-angle eyepiece can add your enjoyment. A telescope must also be attached to a sturdy mounting system to dampen unwanted vibrations when it is repositioned to find a new sky object or to hold it steady if the wind kicks up a little. When all of these criteria are met, then the topic of magnification can be discussed, but there are still limits. The best telescopes will not tolerate any more than 50 to 60-power per inch of light-gathering aperture. A quality, reflecting telescope with a 4-inch mirror should not be pushed beyond 200-power. Where can you find a quality telescope at a fair price? I would first suggest contacting Skies Unlimited serving the Greater Philadelphia, south Jersey, and Lehigh Valley areas (www.skiesunlimited.com) in Pottstown, PA, at 46 Glocker Way, 19465 (888-947-2673). They normally have used and new equipment on their showroom floor, real telescopes, and many at affordable prices. Skies Unlimited has been influential in helping Moravian College upgrade and repair many of the donated telescopes that it has acquired during the past four years. Talk to Bob, Ted, or Dave for a no pressure introduction to the telescope market and feel free to mention my name. They will listen to your needs without trying to coax you into a decision. I really think that is what makes Skies Unlimited extra special. Also, not to be forgotten is Orion Telescopes in California which produces economical instruments that meet astronomical criteria (www.telescopes.com). Examine their GoTo Dobsonians which are reasonably priced and will provide you with years of enjoyable views of the nighttime sky.
 

1156    OCTOBER 14, 2018:   Binoculars Under the Tree?
The more I thought about last weekís article which touted giving a telescope for Christmas, the more I wanted to hype a less spectacular gift, but one that has a greater practical value for the nature/astronomy enthusiast. How about binoculars under the tree? Unless you are a purist and consumed with having the best optical system, you donít have to spend thousands of dollars to own a pair. My price point would be between $100-$200 for a rugged unit that would satisfy both terrestrial and celestial pursuits. Most smaller binoculars are light in weight, ergonomically designed, waterproof or water resistant, adjustable for the peculiarities of each eye, and they are immediately ready for use right from the box. In all cases you will see the image right-side up, over a wide field of view, which will make it much easier to find your target. What potential buyers normally donít realize is that binoculars are an extremely personal item, not because of the way they look, but because of each individualís visual uniqueness. I would inform the intended recipient to come along so that she or he could make the choice to obtain the best fit possible. Stores like Danís Camera City, outdoor retailers like Cabelaís, Hawk Mountain Sanctuary, Skies Unlimited, and even Walmart will provide you with ample opportunities to try before you buy. When you start shopping, youíll see a number on the binoculars, like 8x42, 7x35, 7x50 or 10x80. The first number tells you the magnification which the binoculars will produce, while the second number tells you the diameter of the objective, the initial lens that will be gathering the light that will eventually bring the image into focus by the eyepiece. The magnification also infers something else. Every time you jiggle those binoculars as you try to hold them steady to view that deer or star cluster, vibrations will be amplified by the amount of the magnification. Trying to hold a pair of 15x80s steady is a formable challenge which will undoubtedly result in the extra expense of purchasing a tripod and binocular holder. I think eight power can act as a good limit for your first pair. The light-gathering objective tells you something else. The larger the objective, the bigger the internal components, and the bigger and heavier the binoculars will become; so not only will a 15x80 or a 10x80 pair markedly increase the annoyance of any hand-held vibrations, but they will become unbearably heavy after holding them for just a few minutes. Here are some other thoughts which I consider extremely important. Take the magnification and divide it into the diameter of the lens, and you will have the size of the eyepiecesí exit pupils in millimeters. This is the diameter of the light cone which is produced at the position of best focus. Your eyes must be properly centered on it to see the image. If you are a 20-year old and donít smoke, the iris of your eye should be able to open to about 7mm if properly dark-adapted in a rural locale, but if you are middle-aged, that number drops down to perhaps 5mm or 6mm, so there is no need to consider a 7x50 pair of binoculars that will give you a 7.1mm exit pupil. Your eye simply will not be able to gather all of the light which the binocular is bringing to focus. Eight by 42s or 7x35s would be a wiser purchase. In addition, most of us live in urban or suburban regions where light pollution wonít allow the eye to become fully dark-adapted, and therefore, reach its maximum opening, again negating the need to purchase binoculars which produce the optimal exit pupil for astronomical viewing. Finally, there is something called eye relief that must be considered. The eye relief represents the distance from the outermost lens of the eyepiece to the position of best focus. Viewing in front of or in back of this position will give you a restricted field of view. If you wear glasses and want to have them on while observing, I strongly recommend that you should buy binoculars with an eye relief of 18mm-20mm. That one factor will increase the cost of your purchase, but the binoculars that are bought will have better optics and the comfort of your view will make the higher price worthwhile. Magnification, size, weight, exit pupil, and eye relief are a lot to consider. Purchase wisely, and youíll have a lifelong friend to make the world and universe a more enjoyable place to observe.
 

1157    OCTOBER 21, 2018:   
 

1158    OCTOBER 28, 2018:   
 

[October Star Map]

[October Moon Phase Calendar]
 

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