Astronomy binocular comparisons

Last night was actually clear and sky transparency good! Yes, miracles can happen. Although I was tired and the hour was late, how could I resist? Out came several binoculars and I stepped out onto the lawn for a look. Remember, my sky is almost as light polluted as it gets, so don't expect me to casually report seeing 10th magnitude galaxies. As so many of us know, binocular astronomy in the big city involves more common fare, but it is binocular astronomy none-the-less. Besides, I have a lot of fun just getting out with the equipment on a beautiful night and any night under the stars is better than a night under a roof.

For comparison sake, I started off with a Nikon Premier LX 10x25 compact binocular. Okay, no one thinks of compacts when you think of astronomy binocular, but ANY binocular is better than NO binocular and even a compact will show you things invisible to the unaided eye. Also, for testing purposes, a compact provides a baseline for comparison.

So, I turned the little Nikon Premier LX compact on Jupiter and was rewarded with a tiny disc, though I struggled to see the dots that are Jupiter's four largest moons, Io, Europa, Ganymede, and Callisto. Just not enough image brightness with the 10x25's tiny little 2.5mm exit pupil or resolution with its small 25mm objective to get the job done from my location, but at least a beginner using a compact could say that the "bright star" in the southeast was not a star, but a planet. Next came M13, the Great Cluster in Hercules with a reputation as an object sure to please. Well, not with a compact from my location. Although I was just able to detect M13 with averted vision, thanks to my many years of experience with this famous globular, I doubt a beginner would have seen it at all with any small binocular. Clearly a case of not enough optical muscle.

On to a more conventional astronomy binocular. With a full size Swift 926 10x42 Ultra lite porro prism binocular, Jupiter looked a bit sharper and I could see Jupiter's moons well enough to count them and get a positive lock on their positions. (Never though I'd see the day when I felt this was a big accomplishment, but I never planned to live in a big city, either). Mind you, the view was not spectacular, but at least we were in business. As far as M13, well, it was barely visible as a cloudy smudge and I would have to say that with the Swift Ultra lite 10x42, as with any usable 8x42 or 10x42 binocular, a persistent and determined beginner could pick it up, though it would not be recognizable as a globular cluster. Just not enough optical muscle to resolve stars under my light polluted skies.

Now for the big gun, the Nikon 10x70 Astroluxe binocular. This is my baby. When I turned the Astroluxe on Jupiter, the planet's disc burned brightly and the moons just popped into view as a string of brilliant diamonds. Now that's more like it. As for M13, yes, I could resolve stars at the edge and say positively it was M13, the great globular cluster in Hercules, though it far from what I am used to seeing. Still, score one for the big guy.

Did I learn anything new last night? No, I test equipment like this all the time and I having been using binoculars for astronomy for more years than I care to say. Still it reaffirms the principle that, although bigger is not always better in a binocular, sometimes bigger can make all the difference. Last night, optical muscle showed its stuff.