Sunday, July 19, 2015

 

A Binocular Summer


What better time for them? Binoculars are the perfect tool for astronomy on cloudy, hazy, humid, bug-infested summer nights when I’m reluctant to drag even the smallest telescope into the backyard. Why bother when all I’ll likely see is the undersides of clouds? I can get up the energy to grab my old faithful Burgess 15x70 binoculars for a quick scan of the summer stars between passing thunderstorms, though. Actually, binoculars are useful for astronomy at any time of year.

Not that I, like some people, recommend binoculars as a beginner’s first instrument. While binocs can be great for helping you learn the constellations, allowing you to pick out the missing stars in the constellation patterns under suburban skies, they are not usually enough to maintain a novice’s interest. Most newbies want to look at the stars, sure, but what they really want is the craters of the Moon, the rings of Saturn, and the Moons of Jupiter. Binoculars don’t do a good job with those things.

Even expensive interchangeable eyepiece binocs usually won’t deliver the Solar System goods as well as a cheap 6-inch Dobsonian can. Yes, steadily held 15x binoculars can show considerable lunar detail and the Galilean Moons of Jupiter, but not in the close-up fashion beginners crave. Heck, most newbies are disappointed in how small Jupiter looks at 100x in a scope, much less 10 or 15x in binoculars. Novices:  get a pair of binoculars to supplement, not replace your scope of choice.

That said, every astronomer old and new should have binoculars. Not only are they the ultimate grab and go solution, they are handy for doing things like spotting Polaris in the gloaming, picking out a horizon hugging comet, or getting your bearings in a seldom-visited constellation. But you probably don’t want to spend for Canons or Nikons or Fujinons just to do those sorts of things. You want the vaunted El Cheapo binoculars. Finding a pair of inexpensive ones that’s useful for astronomy is, thanks to the flood of Chinese optics, easier than ever. There are some incredible buys out there for binoculars in all sizes from the little fellows to the giants.

“Glasses” come in a bewildering array of apertures and magnifications: 8x35s (the first number is the magnification, the second the aperture, the size of the objective lenses), 7x50s, 10x50s, 15x70s, 11x80s, 25x100s and more. Where do you start if you want to add a pair to your arsenal? What is the best general purpose binocular for astronomy?

Do you want the short and sweet? The good, old 10x50 is best for most amateurs. It is the perfect balance of field size and magnification. Even those not specifically advertised as “wide field” binoculars have big fields of view that allow stunning views of the Milky Way, the Pleiades, M31, and other things too big for almost any telescope. 10x50s also offer enough magnification to show some lunar detail and to allow a glimpse of Jupiter’s Moons. Despite their fairly large aperture and a higher magnification than many smaller glasses, 10x50s are still small enough and light enough for most adults to easily hand-hold for considerable times while observing the sky (after a little practice anyway).

How about the lower powered 7x50s? They boast wider true fields of view, but… In binoculars, less power means “won’t go as deep” from most locations. Even from darker sites, you will see dimmer objects with the higher magnification of 10x50s. Higher power darkens the background sky in the binoculars, spreading out any light pollution present.  When you are viewing extended objects like nebulae or the Andromeda galaxy, their light is also spread out and they are dimmed too, but even so the darker sky background makes them appear to stand out better, makes the contrast between object and sky seem higher.

You will definitely see more stars with higher power binoculars; it won’t just be a pseudo contrast effect either. Stars are not dimmed by increased magnification, since they are point sources and cannot be spread out. The higher the magnification, the darker the sky, and with the stars remaining the same brightness, the higher the contrast.  You can see dimmer stars with increased magnification.

A little more power has one other benefit. The main impediment to doing the Messier with binoculars is that some of the objects are small enough to be hard to identify at lower power. I find 10x helps me pull out a few more of the little ones than I can at 7x. I can (barely) make out that M57 is not a star in 10x50s; I can’t do that in 7x50s. Stick to 10x50s.

Can you go smaller than 10x50s and still see anything? Sure you can. Magnification is really more important than aperture when choosing between 35mm and 50mm binoculars. Also, lighter binoculars are easier to hold steady, and you will see deeper if your glasses are held steady. Our 8x32 binoculars regularly show as much—and sometimes more—than our 7x50s. The catch? Cheap 35mm binoculars are often poor optically. Generally, the cheap brands are less good in that regard than 50mm glasses. Yes, our 32mms give our 50mms a run for the money, but our 32s are rather expensive Canon roof prism binoculars.

So, you want a pair of 10x50s. Where do you get them? You could trot down to Wal-Mart and buy a pair for 30 – 50 bucks. That is actually not a bad idea as long as you are willing to stand in the return line and keep exchanging binoculars until you get a good pair. What’s usually wrong with them?  Optically most Chinese binoculars, which are all you will find at WallyWorld, are fine. It’s their mechanical alignment that is off.

Take your new Bushnell (or whatever) glasses out, and point ‘em at a bright star. Adjust the interpupillary spacing (how far apart the binocular halves are) until you see one big round field of view (not a figure 8 shaped field like in the movies). Focus as best you can and hold the binoculars as steady as you can—gripping them at the objective end is best. Do you see a single star or a double star? If you see two bright stars instead of one, check focus and fool with the spacing. If your eyes still have to work hard to merge the two images, take the binoculars back and exchange them for another pair. The ones you have will be a headache—literally.

How can you avoid mis-collimated binoculars? You could try purchasing from an astronomy binocular dealer like Orion. You might get better quality control, but not necessarily if you lowball it. In the 50-75 dollar class their binoculars come from the same Chinese makers as Wal-Mart’s, and if you have to return ‘em, you will have to do that by mail. In my opinion, stick to locals if you want “real cheap.”

Which brand should you choose? Bushnell? Meade? Celestron? Barska? Tasco? It really doesn’t matter. At this end of the price scale, brand names are meaningless. They all come out of the same few Chinese factories and all are more alike than different. Options? Aren’t many offered. See if you can get a pair with a case of some kind. How about a tripod socket, so you can mount the binoculars on a camera tripod (with the help of an L shaped tripod adapter you can get cheaply from most astronomy dealers)? That might make a difference to you; it doesn’t to me.

Frankly, I don’t like binocular mounts for non-giant binoculars. But not because they can’t help steady the binoculars and let me see deeper. They can; even a cheap camera tripod will help. It’s because they don’t fit in with the way I use binoculars, especially in the summertime: grab ‘em up, run out on the deck for 10-minutes of looking, run back inside. I don’t want to fool with tripods under those conditions.

What can you expect to see in inexpensive 10x50s? A lot. Many Messiers (most of those not visible are not visible because, as above, they are too small). I have had a terrific view of the elusive and difficult M101, the Phantom Galaxy, from a very dark site with a pair of Simmons (WallyWorld) 10x50s. Moon craters in proliferation. Beautiful awe-inspiring views of the summer Milky Way from dark locales. A better look at M31, the Andromeda Galaxy, than I’ve ever had in a telescope.

Downsides to the cheapies? Other than the above alignment problems, not many. Mostly just field edge sharpness in wide-field models and fogging up in the summertime when the binoculars are taken out of the air conditioned house. The former isn’t much of a problem; you’ll still have plenty of useable field. Fogging up? Makers of more expensive glasses prevent internal fogging in their binoculars by purging them with nitrogen (external lens surfaces will still fog). Solution? Put the glasses with their lens caps on outside half an hour before you use them on sultry nights.

Are there any 10x50s to stay away from? Basically two types: zoom binoculars (of any maker) and binoculars with ruby-tinted lenses. The problems with zoom binoculars are that they are not as sharp as single power binoculars at any setting and their fields of view at lower powers are constricted. Tinting the lenses of binoculars red was all the craze with the cheap sellers for a while. The only reason for doing that, really, would be to lessen the impact of chromatic aberration in the most poorly made glasses. It provided no other advantage and was a tip-off that the binoculars in question would be yucky. Luckily, I don’t see many of these horrors anymore.

10x50s are a good choice for astronomy, but they are hardly the only choice. There are others that have been perennially popular…

15x70s

These are, if you haven’t picked up on it, my favorite astro-binoculars. No, they are not as easy to hand-hold as 50mm glasses, but it is still possible to use them without a support with a little practice. More aperture and more magnification really are a good thing. Not only does pumping the power up take you a bit deeper from less than perfect skies, you’ve got the reach and resolution of bigger objectives, too. At 15x, the Moon looks good, real good, and the Galilean moons are easier because they are more separated from the planet—which is now obviously a little disk. Most astronomy oriented 70mm binoculars are of the wide field variety, so stuff like M31 and the Double Cluster still looks terrif.

Brand? Since we are talking bargain glasses, the same applies as with the 50s—it really doesn’t matter. All come from the same factory or two, and all are similar in quality. There are a fewer brands to choose from simply because fewer importers choose to market 70s. Some of the usual players are Celestron, Meade, Barska, and Orion. Amazing to me is how cheap they are:  between 60 and 100 bucks gets you a pair. Surprisingly, the low price doesn’t seem to reflect quality. Most I’ve tried have been reasonably well built and optically good. My own Burgess 15x70s set me back all of fifty bucks in 2003 and have been at my side ever since.

20x80s

If 70mms are cheap, 80s are crazy cheap compared to what they used to be, with 100 – 125 bucks getting you a pair of really big binoculars from Celestron, Barska, Orion, and the other usual suspects Sounds great…but. Bigger isn’t always better, boys and girls, at least not in astronomy. Problem one is that none of the low-ballers sell 11x80s in this price range. They are all 20x. Do you think it will be easy to hold 20x binoculars of any size steady?

Adding to that is Problem Two:  cheap binoculars are generally heavier than expensive ones, and 80mms are naturally heavy whether cheap or expensive. To get much use out of 20x80s you will need a tripod or, way, way better, a mount designed specifically for binoculars. If that is your bag, fine. It ain’t mine. Again, I usually don’t want to be tied down with a mount when it comes to binoculars.

Big boys

Big binoculars, 100mm and larger aperture binoculars, are an entirely different kettle of fish. They are more a telescope replacement than a supplement. They are most assuredly not grab ‘n go friendly in any shape or form or fashion. I use them for tasks that a telescope can’t do as well as they can—showing pseudo 3-D views of wide fields—not because I want something lighter or more convenient. That’s the only way to approach large binoculars. If you accept those things, big dogs, like my 25x100 Zhumell Tachyons, can amaze.

I have quite frankly never had as stunning a view of the Sagitarius-Scorpius Milky Way with any instrument as I had with the Tachyons at the Chiefland Astronomy Village. M31? You can’t get a 3-D view of something all those light years away, but that’s not what your brain thinks. You are using both eyes, so you must be seeing in three dimensions. M32 was in the foreground and the whole thing looked just terrific.  In some ways the real giants are also more versatile than smaller binoculars. You still get a very wide field, but you get resolution of the brighter open and even globular star clusters. M57 is a tiny perfect ring. Saturn’s ring can be seen (barely). The Moon looks as good, at least as good as in my StarBlast.

Despite all that goodness, I use my Tachyons once or twice a year at most. Why? The mount. Large binoculars require mountings. While the Pete Peterson EZ Binocular Mount I built for them is lighter than some similar mounts and works better than most, it’s a fair hassle to set up and balance. That means I reserve the Tachyons for times when binoculars will really shine:  a good, large comet, a visit to a dark site when I want to go more casual than setting up a telescope and doing an observing project.

Like other binoculars, the Chinese optical revolution has made 25x100s much more affordable than I’d ever have dreamed. You can buy from sources that include Celestron and Orion at prices that range from 250 – 350 dollars. But think long and hard before you do that. You’ll need to budget at least another 150 – 200 dollars for a mount kit (like the Peterson EZ), and several times that amount for a store-bought rig—which likely won’t work as well as the kit. One other caution:  if, like mine, your eyes have a hard time merging images in even well collimated binoculars, you may not like 25x power binoculars. The higher the power, the harder it is to merge images.

Part of me says that if you want to go big, you should really go all the way, and invest in something like the Oberwerk 100s. These binoculars feature interchangeable eyepieces, an integral fork mount that’s far more convenient than any binocular mount, and eyepieces with a 45-degree viewing angle to make the binoculars more comfortable to use when pointed at higher altitudes. I’ll tell you, if my eyes had an easier time merging images at high power, I would sell several telescopes, get a pair of these pups, and never look back.


Despite the few caveats above, binocular astronomy can be a joy. If you’ve never done the deep sky with glasses, it can give you a whole new perspective. I’d always used binoculars for astronomy, but usually only when it wasn’t convenient or comfortable to use a telescope—like this summer. I have, however, gone beyond that a time or two, and observing with binoculars seriously is like opening a new window. I did the Messier, kept going, and was surprised at how far I could go into the night. It was like seeing everything for the first time again, which is a very good thing.

Comments:
Great read today for me Rod. Our club has gone thru binos like s**t thru a goose. Bigger is certainly not better. Our 25X100's get little use because of the big fork mount they need, might as well get a scope out. We just finished trying out the Canon IS line and settled on the 12X36. They outperformed the bigger 15X50's because of weight. I agree that binos are best used as a grab and look item and those that work best for that are the ones that get used. My personal favourite bino is a pair of Pentax roof prism 9X63's. ....Dwight
 
I have Eagle Optics ($350 or so) 10 x 50's for birding and they are also great for astronomy and guaranteed for life if you can produce the body. I use them without fear:)

In the fall I keep my 20 x 80 Celestrons ($100 Amazon and easy to align)on a tall tripod with a large fluid head. Walk out the door and looking.

As I get older its the 20 x 80 on a tripod that gets the most use. IS would be nice but I'm not spending $1000 on a 50mm binocular:)

Good read Rod.
 
I have bought spotting scope in
here, i think use spotting scope bester than binocular
 
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