Telescope Buyers' FAQ - Part Nine
How Do I Hold Binoculars?
This section was written by Jay Freeman.
If you don't have a tripod (and tripods are sometimes a little clumsy, and are often difficult to use when the binocular is pointing near the zenith), it is important to know how to hold a binocular correctly to achieve maximum steadiness.
The way most people tend to hold a binocular is with one hand on each side of the middle of the body - roughly where the prisms are in a conventional 7x50, say, so that the left hand is directly to the left of the centre of gravity of the instrument and the right hand is directly opposite it, to the right of the centre of gravity.
For most people, there is a better position. Imagine that you are holding the binocular to your eyes, with your hands positioned as just described. Now, slide your hands along the body of the instrument, toward your face, until only your small and ring fingers are curled around the back end of the binocular body. In this position, the binocular feels a little nose-heavy, because you are supporting it behind its centre of gravity.
Now curl each thumb up as if you were making a fist, and flex your hands so that the second bone in from the tip of your thumbs are pressed up against your cheekbones (counting the bone in the part of your thumb where the thumbnail is, as the first bone). This makes a quite solid structural connection between the body of the binocular, through your hands and thumbs, to your face, and markedly improves how steadily you can hold the instrument. Similarly, curl the first and middle fingers of each hand around the corresponding binocular eyepiece, to provide a little more structural connection (and perhaps also some protection from stray light). In this position, your hands are not far from where they would be if you brought them to your face to block out stray reflections while peering through a store window at night.
For most people, this position leads to markedly steadier viewing, but if the binocular is especially long and heavy (say, a 10x70 or an 11x80), the out-of-balance position can be quite tiring. In that case, move one hand out to the objective end of its side of the binocular, so that you are supporting the instrument on opposite sides of its centre of gravity, but with some structural connection between it and your face; namely, the other hand. When the hand way out there gets tired - just switch hands.
For each person, there is a limit to how heavy and / or how powerful a binocular can be, before there is no way for that person to hold it steady enough. I am an averaged-sized adult male in reasonable physical condition, and I find I can hold a 10x70 (Orion's) steadily enough to use indefinitely on astronomical objects. But I have an old Celestron 11x80 that doesn't look much bigger or heavier than the 10x70 that I can only use for a few minutes before my arms get tired. As a 12-year old I am sure I could have used a 7x50 indefinitely with no problem, but at a younger age I might have had difficulty using one continuously. Your experience may vary with your strength, size and condition. Try before you buy, if at all possible.
What Are Some Eye Relief Figures?
If you need to wear eyeglasses while looking through binoculars (presumably you have astigmatism, but if you require many diopters of correction you might need to as well) you need reasonably good eye relief. Dana Bunner contributes the following table:
|Model||Advertised ER||Measured ER|
|Bausch & Lomb 7x26 Custom||16||15|
|Celestron 10x50 Pro||15||10|
|Celestron 7x42 Ultima||23||19|
|Celestron 7x50 Ultima||20||16|
|Celestron 10x50 Ultima||19||17|
|Celestron 8x56 Ultima||21||11|
|Fujinon 8x40 BFL||19||17|
|Fujinon 7x50 FMT-SX||23||20|
|Fujinon 10x70 FMT-SX||19||17|
|Minolta 7x50 Standard||18||16|
|Minolta 10x50 Standard||?||9 (FYI)|
|Minolta 10x50 XL||18||16|
|Nikon 8x30E Criterion||13||13|
|Nikon 7x50 Windjammer||16||16|
|Optolyth 10x40 Touring||13||12|
|Pentax 8x24 UCF||13||8|
|Pentax 7x35 PCF||14||9|
|Pentax 7x50 PCF||20||10|
|Swift 8x25 Micron||13||11|
|Zeiss 7x42 B/GA T Dialyt||19||18|
|Zeiss 20x60S||?||14 (FYI)|
What Books and Star Charts Are Recommended?
If you don't know the constellations, you might want a book that will help you learn them. A "fun" book for those just learning the stars is The Stars, A New Way of Seeing Them by H. Rey, which presents a non-orthodox way of drawing the constellations so they are easier to visualize.
You will probably want a beginner's guide, such as the book by Sherrod mentioned above. Sky Publishing has some introductory materials that would probably be as useful, which you get for free when you subscribe to Sky and Telescope.
Petersen's Field Guide to the Stars and Planets comes highly recommended. It is very inexpensive ($13), small and handy to use at the telescope. It has a good discussion about stars, planets, nebulae, and galaxies and has a very complete albeit small-scale star chart, along with a the usual tables. It has long lists of deep-sky objects for each area of the sky.
You will need a bigger star chart than is included in Petersen's. Try Sky Atlas 2000.0, by Wil Tirion. The field edition, which has white stars on a black field, is probably more useful than the desk guide. It is also printed on heavier paper so is more resistant to dew and the rigors of the night. For beginners, buying Uranometria 2000.0 is probably a mistake. Yes, it is the "best" star chart, but the scale is impossibly small- when the Orion constellation takes up four separate pages it is really hard to use for beginners.
Burnham's Celestial Handbook ($36). This three volume set is billed as "An Observer's Guide to the Universe Beyond the Solar System" rather all-encompassing claim, which it manages to live up to. Information on every item of interest you can think of: galaxies, double stars (optical and binary),variable stars, nebulae, etc. More information than you could use in a lifetime. I consider this a necessity.
Sky and Telescope's 100 Best Deep Sky Objects. About $5, which is kind of expensive for a list, but it sure makes it easier to figure out what to look at when you are just beginning. The items are sorted by Right Ascension, which makes it real easy to figure out which ones are currently up.
What About Computer Programs?
There are too many types of computer programs that I can not review, as they do not run on my machine. I think there should be a FAQ just for all the computer programs.
About this FAQ
This FAQ is a copyright work. You have my permission to reproduce it however you like, as long as you don't make any money off it and you leave all the attributions and the copyright notices. This FAQ is Free, but if you find it useful a small donation would be welcome.
Slc.Dennis Bishop 470 20th West #23 Rosamond,Ca.93560 Wanted: Donations of old Telescope Parts
Author: Dennis Bishop