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Seeing double the natural way – looking up with both eyes and binoculars

The best way to look at the stars is to lie back in the grass on a hill side on a warm summer’s night in a region free of light pollution and look up. The only way to improve on this is to add binoculars. And when it comes to splitting doubles, this is doubly true!

Bring on the doubles! - 25X100 Zhummel binoculars.

Binoculars make a terrific double star instrument because you are doing what comes naturally – you are using both eyes and you are looking up. And there are loads of beautiful doubles that provide absolutely charming splits when viewed properly in binoculars. What’s more, binoculars give you a sense of context. Because they give a correct image and wide field of view, the transition from naked eye is not so abrupt or confusing. It’s a great way to learn your way about the night sky and to keep what you view in context.

I should add that once you get past the smaller binoculars it is neither simple, nor cheap –  it actually gets about as complicated, cumbersome, and expensive as using a telescope. Image stabilized binoculars maintain the size and portability we have come to associate with binoculars while making it easy to get a steady view, but they are expensive. However, most of the time I use larger binoculars and their mounts are  as heavy and awkward as any mount and as expensive. There’s no free lunch here – but for me the binocular astronomy experience is well worth the effort and price.

But I have a confession to make. Until very recently I didn’t consider this the case. I thought binoculars did a poor job with doubles – but I now think this was my special hurdle to leap and now that I’m over it I’m in bin ocular double star nirvana – so I decided to provide some basic guide lines for splitting doubles with binoculars, plus a short list of some especially useful binoculars doubles that range from easy to difficult and will give you a way to test yourself and your binoculars, should you care to.

My knowledge comes the hard way – I acquired it through numerous hours of observing and most of them were relatively futile. If you want to read the whole saga of my personal journey with binocular doubles, go here.  But I really think most people have a far, far easier time of it with these inexpensive and highly portable instruments. So let’s get started.

Short List of Binocular Doubles

First, here’s a list of some excellent spring and summer binocular doubles arranged in order of the easiest to the most difficult. The top of the list can be split by any binocular, the mid section takes a good astronomy binocular, such as a 10X50, and the last few call for big astronomy binoculars in the 20X80 or 25X100 range – which can now be acquired quite cheaply, incidentally, but mounting them is the rub.

  • Mizar and AlcorMany can split these two famous stars in the handle of the big Dipper with the naked eye, but for me it always takes binoculars – any binocular.  RA:  13h 24m   Dec:  +54° 56′ – Mag:   2.2, 4  – Sep:  11.8′ (708.5″)  – PA :   71°
  • Epsilon Lyra – Double Double – No, I don’t mean to actually split each star – I mean the initial split into Epsilon 1 and Epsilon 2 – that’s easy for any binocular and since these are in the same low-power binocular field as Vega, easy to find. I am able to split these with my  6.5X21 Pentax “Papilio” – the “butterfly” binoculars.  RA: 18h 44m   Dec: +39° 40′  Mag.: 5, 5.2 –  Sep. : 210″
  • Nu Draconis – The famous “Dragon’s eyes” are delightful because the split is clean with just about any binocular and the stars nearly identical. RA: 17h 32m Dec: +55°11′  Mag: 4.88, 4.86 Sep: 63.4″ PA: 311°
  • 16 & 17 Draconis – This pair is more widely separated and easier to split than Nu, but I listed it after Nu because it is a bit more difficult to find. RA: 16h 36m Dec: +52°55′  Mag: 5.4, 5.4 Sep: 90″ PA: 196°
  • Albireo – Beta Cygni – I think this has got to be one of the most popular double stars there is, and while it mark’s the Swan’s head, it is easier to find with the naked eye, than with binoculars. The reason is it’s in the heart of the Milky Way and it’s hard to know which is the star you seek because there are so many. RA: 19h 31m Dec: +27°58′ Mag: 3.4, 4.7  Sep: 34.7″ PA: 55°
  • Psi Draconis – I know I have the right star when I see the perfect little kite asterism  in my binoculars with Psi as the brightest member – RA: 17h 41.9m   Dec: +72° 09′  Mag.:   4.6, 5.6  Sep:   30.0″  PA:   16°
  • RegulusAlpha Leonis –  With a separation of nearly three minutes of arc you would think this one would be up with the other easy stars – it’s isn’t because the magnitude difference is so great – great enough for me to call ont he light grasp of an 80mm or 100 mm binocular. RA: 10:08:22.1 / Dec: +11:58:01 – Mag.: 1.35, 8.12  Sep.: 177.6  PA: 207°
  • Mizar – Yep, this is the brighter half of Mizar and Alcor and it does make a lovely split, but it takes more binocular muscle – more like 20X and easier with 25X.  RA:  13h 24m   Dec:  +54° 56′   –  Magnitudes   2.2, 3.9 – Separation  14.3″ – Position Angle    153°

Short check list of guidelines for getting the most from your binoculars

Garrett Optical 28X100 binoculars on Universal Astronomics Millenium Mount with rotating beach chair - to me the perfect chair to sit in while using binoculars since it both leans back and rotates, but hard to find and the most recent version of this chair I found was not that well made.

From my experience I’ve developed some basic guidelines for splitting doubles with binoculars.   Many of them you probably already do. If so, treat this as a reminder.

  1. Wear your glasses if you have astigmatism – otherwise do without.  And if you need glasses, seek binoculars with long eye relief and flexible eye cups that roll back.  You only need to see the center of the field to split a double, but the whole field is useful for finding the double.
  2. Sit down – or better, lie back in a lawn chair – you must be comfortable. Get in a position where you are looking at your target area without strain, then bring the binoculars to your eyes. This is important. Even with a nice Parallelogram mount I frequently see people raising their head and straining their necks to look through binoculars. Take the time to make the mount do the work for you.
  3. Hold the binoculars steady – even 7X50s will benefit from being on a tripod, or parallelogram mount unless, of course, they are the image stabilized types. Most people think they can hold binoculars steady. Wrong! And this is doubly wrong if you’re trying to split close doubles. An ordinary photo tripod can hold small and medium binoculars, but will likely result in a pain in the neck. I can’t use one for anything except objects that are so low the atmosphere becomes a problem. However, I know excellent observers who use such amount for all their  binocular observing. I much prefer the kind of parallelogram mount that puts the binoculars to one side of the tripod or pier so you can observe comfortably while seated in a lounge chair. This isn’t laziness – it’s practical considerations related to seeing well.
  4. Focus carefully – very carefully – with center focus types remember to focus first the left eye with the right closed, then do the diopter adjustment for the right eye while keeping the left eye closed. I know everyone should know this already, but it’s surprising how many people have used binoculars casually for years without being aware of it.  Acceptable focus for land views just isn’t the same as the critical focus needed to split close doubles. Once you have the diopter set, you can leave it alone and just use center focus.
  5. Get the interpupilary distance right!  That is, make sure the binoculars are the same distance apart as your eye. This is another one of those things that might evoke a duh! But the truth is, your brain wants to see a single image and might be working overtime to give you one because the binoculars aren’t adjusted properly for your eye. (This is also true if your binoculars are out of collimation – but evaluating and correcting collimation is a topic beyond the scope of this post.)
  6. Spend time on target – Look for at least one solid minute – don’t expect instant success. Don’t fiddle with the focus forever – give your eyes time to adjust. This is one of the key instructions in Crossan and Tiron’s “Binocular Astronomy.” They write:”the most important thing in observing is to really look – a mere glance at an object or a field is simply not enough. You must keep your eyes at the oculars for a full minute at a time.” I can’t stress this enough. over and over again I see people taking mere glances and thinking they have seen all that can be seen. As Holmes told Watson: “You see, but you do not observe.”
  7. Relax your eyes – let them focus at a distance and get used to it. I wish I could explain this better. I feel it’s important, but I’m not sure exactly how to describe it. If I’m in doubt I take down the binoculars and just try to let my eyes focus on the stars. Then I come back to the binocular view.
  8. And if all this fails to deliver sharp star images, maybe you have a problem similar to mine – back off from the eyepieces an inch or two, move your head about some – find the correct head position – the one that works and yields sharp stars.

This last has driven me crazy and continues to puzzle because believe me.  Points one through seven didn’t make a difference for me until I could settle the issue of point 8 and right now I’m not sure how many others have a similar problem, but I think it’s relatively few.

I’ve been to both the eye doctor and my massage therapist and right now the one whose advice makes the most sense relative to this situation is my massage therapist. She noticed me holding my head a bit funny and she knew I had flexibility problems with my shoulder and neck. These apparently don’t come into play when I am leaning over the eyepiece in the diagonal of  a refractor or catadioptic telescope – or for that matter, looking directly into the eyepiece of a reflector. But when I look up to look through binoculars, all bets are off. What feels natural to me simply isn’t the position that yields sharp star images. For years I have blamed this on the quality of the binoculars. Then for a while I blamed it on what I perceived as my astigmatism. But tests show that astigmatism is slight and what I am finding is critical is getting my head into a position that works – even if it feels unnatural to do so.

I discovered this by backing away from the eyepieces as much as two or three inches and moving my head around, tilting it in various angles.

My advice to you? Don’t worry about this unless you’ve tried everything else and are still having problems getting sharp star images.

Meanwhile, check out some of the doubles on the short list. Warm up by trying the easiest first – and get your focus right on them. Most are conveniently grouped with other bright stars and easy to track down – and each is distinctive. Even if you have seen them all in telescopes, the binocular view is different and special. Give it a try and see if you don’t agree.

More binocular astronomy resources:

Binocular  Highlights” by Gary Seronik – this is a great book to begin with. It mentions several double stars, but a lot of other good objects to look for with your binoculars. Also, scroll down his web site for some excellent binocular reviews and related suggestions on mounts.

Review of Binocular Mounts – Go here to learn of  some of the possibilities of commercial binocular mounts. If you’re handy with tools, there are plans here for making a parallelogram mount.

Binocular Astronomy, Crossen and TironAgain, a good guide. I have the first edition – have not seen the newer one advertised here, but I assume it is at least as good.  This is a general guide with lots of solid observing advice and several specific doubles.

Binocular Double Star  Club – Here’s a good list to whet your appetite – and if you’re into “awards,” go for it.