BinocularsBlog – Advice on Digital, Waterproof, & Compact Binoculars for Bird Watching, Sports, Astronomy, Night Vision, & more!

Customers frequently ask the light transmission percentage on various models of binoculars, since this is a spec rarely specified by the manufacturers. I suspect there are several reasons for light transmission percentages not often being posted as a spec for a binoculars. One, there is no standardized way of measuring light transmission, so even if posted, it means relatively little unless it is the result of a test where there was a direct comparison with other models. However, the percentage means little outside of this test since no one has devised a test that is universally used by all manufacturers. Another reason, I suspect, is that numbers can be misleading and often suggest a significance they do not have. For instance, I read somewhere that the human eye cannot detect differences in light smaller than 3%. That suggests that a difference between a binocular with a 94% light transmission and one with a 96% transmission means very little, if anything. Lastly, no one test can duplicate the actual conditions where a binocular will be used. May not be very scientific, but I have seen wide variations in image brightness performance for a specific model of binocular under the lights of a store, out in the field at dusk and, finally, under conditions of full darkness. Awfully hard to predict this aspect of binocular performance until you get the binocular out and test it for a specific situation and, again, the only real test is a side by side comparison. Specs like exit pupil, lens coatings and even light transmission, when posted, can only take you so far.

A common astronomy question I get this time of year from beginner's is, "What can I see?". To answer, I patiently explain that it's not so much a matter of "What" as it is "How much". This is true in binocular astronomy as well as telescope astronomy. For instance, you don't even need a binocular to see Saturn or Jupiter or Mars. You can see those without any optical instrument at all. All a binocular or telescope does is show you more detail. In fact, if you are observing from a truly dark sky site, you can see the Andromeda galaxy, many star clusters and some nebulae with your naked eye. No optics needed. All a binocular (or telescope) does is show you MORE of these objects and MORE detail in these objects. The extent of each is a matter of the binocular or telescope used.

Definitely starting to see some birds moving through the area. Last week, for instance, on Thanksgiving day, impressive numbers of Sandhill Cranes moved over the Chicago area suburbs, moving south. As usual, I heard them long before I saw them, but I did stop pedaling my bike long enough to admire them through my Zeiss Victory 8x20 binocular. Sandhill Cranes are special to me, since I spent so many years in central Nebraska, where they are a spring phenomenon. There, in March and April, you can see them by the many thousands, standing in fields along highways and roads. No need for a binocular or spotting scope to enjoy them, either, though a good binocular adds to the fun. Believe me, it is well worth a trip to central Nebraska in the spring to see these birds. This trip should be on every birder's list.

Being citybound under light polluted skies has forced me to take what is given to me as an astronomer and one of those opportunities has been the moon. The last time I got serious about observing the moon was when I began astronomy some nearly … oops! Let's just say a long time, ago. Friday night, though, I cheated a bit, though. I could see the full moon through my walk out window and since it was cold and windy, well, I just got a pillow, laid out on the floor, grabbed my Nikon Prostar 7x50 binocular and my moon map and oberved through the glass. Not as pure an observering approach as I usually practice with my binoculars, but, then, I am getting old. Right? Either that, or those astronomy binoculars are gaining weight like the rest of this holiday season.

It's been awhile since I have had clear skies, but the clouds finally parted last night and I was able to check on Comet17P/Holmes. In the week since I have seen it last, the comet has expanded, yet again, and as its light continues to expand over a wider area, the comet becomes harder to see. With the full moon last night, I could just see it in my Nikon 7x50 Prostar binocular. Thinking I'd get a better look with my 10x binocular, I then tried my Nikon 10x70 Prostar. Still visible, but the even that little bit of extra magnification made the comet stand out a bit less against the sky background. A spotting scope at 20x was even worse. Sometimes, less really is more.

What does a binocular astronomer do when the skies refuse to clear? She plays with her collection of star maps, not only because she loves star maps, but also to be ready with a menu of objects to be seen when the skies clear. For appetizers, my binocular astronomy list typically begins with some lunar work (touring marias and some of the larger craters), checking on the observable planets, splitting some of the season's best double stars, and admiring the colors of some of the season's brighter stars. (Yes, Virginia, stars do have color and, in a quality binocular or telescope, they are lovely, indeed.) The entrée for my binoculars, though, is deep-sky objects and, of these, open clusters are my favorite. All I want for Christmas is to see the Pleiades in my Nikon 10x70 on a clear, cold winter night. That is a gift beyond price.

The current trend in astronomy binoculars is more magnification. Today, for instance, the best seller in an astronomy binocular is the 20x80 and for many types of binocular astronomy, this is a great choice. Let's not forget, though, that with magnification there are trade-offs. Yes, sometimes less is more. For large open clusters and extended nebulae, my favorite is still the venerable old 7x50. With the super wide field of view of a 7x50 astronomy binocular, it is much easier to delineate the outline of large Collinder, Stock and Melotte open clusters. In fact, it is nearly impossible to separate these loose scattered star clusters from background star fields with the tiny fields of a 20x and 30x. It's a classic matter of not seeing the forest for the trees, so to speak. So, Happy Holidays, everyone! I have now given you an excuse to add another astronomy binocular to your list.

The rain, drizzle and clouds are stubbornly staying with us, here in the Chicago area. Didn't stop me from doing 80 miles on the bike, this weekend, but it did prevent me from checking up on the comet. Last time I Comet 17P/Holms, last week, through my astronomy binocular, it had expanded, considerably and, as such, appeared a bit less brilliant. This is, of course, a matter of its light being spread out over a larger area - I could still just see it as a nebulous puff of fog, even in my light polluted sky. What will the comet do next? My Nikon Astroluxe 10x70 binocular, my newly acquired Nikon Prostar 7x50 binocular and I stand ready. (What can I say? A girl can't have too many astronomy binoculars.) Stay tuned.

As "no brainer" advice goes, "use the strap" on your binocular is near the top of my list. It is something I preach and practice, religiously. The number one reason binoculars get damaged is not from wear and tear, but from being dropped or banged against a hard object. This is especially true when using astronomy binoculars. Look at it this way. You are in the dark, fumbling around with a star map, flashlight or, perhaps, also dealing with a telescope. Believe me, it's easy to lose your grip on a binocular under these circumstances. This is especially true on giant astronomy binoculars and doubly so in cold weather when wearing gloves. Joanie says, "use that strap or get the binocular on a tripod".

A lot of parents want to buy a binocular for their kids for the holidays, but are reluctant to spend the money it takes to get a decent binocular. Let's face it, a quality binocular can be expensive. The good news, though, is that OpticsPlanet picked up a special run of the Bushnell Hemisphere 8x32 binoculars from Bushnell with less expensive lens coatings than the standard Bushnell 8x32 Hemisphere. The result? You can now buy one of these mid sized binoculars - small enough for a youngster to hold - at a great binocular price. In fact, at this low sale price, you can buy a Bushnell Hemisphere 8x32 binocular for each youngster on your shopping list.

For those of you who were planning to get up at 5AM and do a bit of astronomy before breakfast, but "accidentally" forgot, never fear, Joanie is here! I ventured out onto the frosty lawn in my bare feet and nightgown, binocular around my neck, just to bring you my early morning binocular astronomy report. Here's what you missed.

Venus is an area of faint stars and, as such, shines all the more like the brilliant beacon it is. It is absolutely gorgeous and well worth getting up early to see. Mars is next and is currently surrounded by lovely stars in Gemini, but still outshines them all. In my Nikon 10x70 Astroluxe, it appeared as a small, but intensely orange disc. Saturn is back to the east a bit and is doing its thing in Leo. In my binocular at 10x, I couldn't see the rings, but I could detect an ever so slight bulge to the tiny disc. My last stop was in the neighborhood of Auriga for some open star clusters. M35 on the border of Gemini, then M37 and M36 in Auriga were quite easy, even with all the light pollution. M38, though, escaped as usual. That one usually requires a trip to the park for a darker sky and … well, I just wasn't dressed for it. Besides, the aroma of my coffee beckoned. Stay tuned, though, for more reports from the binocular lady.

The clouds moved in this weekend, but I was able to give my astronomy binocular a workout on Friday evening, just before the sky became overcast. I am happy to report that Comet 17P/Holmes is alive and well and seems to have added some girth since I saw it last week. I even had some of my fellow apartment residents express an interest in what I was doing.

That reminds me of a problem unique to binocular astronomers. It's something that rarely happens to astronomers with telescopes, at any rate. You see, more than once, as I've observed under the stars with my binoculars, I have been questioned by authorities as a possible "peeping Tom" suspect. Apparently, peeping Toms don't use telescopes, just binoculars. My recommendation to all my fellow binocular astronomers is to always have a star chart at your side as evidence of what you are doing.

Customers sometimes ask how long I have been using binoculars. The answer is simple - for a very long time. Believe it or not, I remember the days when many of the common binocular features found on inexpensive binoculars, today, didn't even exist and when these features did first appear, they were available on only the most expensive binoculars. How old are you?

"You know you are an old binocular user" if you can remember when there was no such thing as multi-coating - only single layer lens coatings existed on binoculars. Yes, there was even a time when having all the lenses in a binocular coated with a single layer of magnesium fluoride was a big deal. "You know you are an old binocular user" if you can remember a day when roof prisms were the new kid on the block and the only roof prism binoculars available were very expensive. In those days, porro prism binoculars outnumbered roof prisms by at least ten to one. Even when roofs did start appearing in any numbers, there was no such thing as "phase-correction" (PC). That appeared many years, later. "You know you are an old binocular user" if you can also remember how hard it was to find a binocular with long eye relief or one that was even waterproof. Armoring was even a rarity. "You know you are an old binocular user" if you can also remember a day when NO binoculars were made in China. Oh, how things have changed in the binocular market.

The clouds and have moved into the Chicago area and, as they are often wont to do in the Chicago area, they've taken up long term residence. So how fares our wonderful Comet 17P/Holmes? Sure, I can get online to check the latest reports, but I became an astronomer long ago, precisely because I wanted to see the heavens for myself, not rely on what others have to say or have to look at pictures for a view. Of course, if I didn't have a job, I could pick up my binoculars or telescope and move to an arid climate with clear skies. Until I retire, though, I must be ever patient. The skies will clear and I will be ready, binocular in my hand and telescope at my side.

Question: Is there one binocular that can be used for astronomy, birding, hunting, sports watching, wildlife viewing, surveillance, boating or just about anything that requires a closer look? Answer: Yes, a waterproof 8x42 binocular is the world's universal binocular and any 8x42 waterproof binocular of reasonable quality can be used for any binocular application. An 8x42 may not always be the very best choice for a specific application, but it can always be used to some extent for any binocular application. Do you have your 8x42 binocular, yet?

As I always do when the sky is clear, I ended this previous Friday under the stars with my astronomy binocular. This weekend I had challenged myself to find some open clusters in Cassiopeia with my Nikon 10x70 Astroluxe, but, of course, a check on the comet was mandatory. As of Friday night, Comet 17P/Holmes was still bright and, in my binos, was maintaining a fairly bright central core with a dimmer halo ring. Last night (Sunday), I was amazed to see that the comet had lost brightness, perhaps a full magnitude to my eyes and the core had a distinctly washed out look in the big Nikon binocular. With this comet, though, who knows what will be next? Comet 17P/Holmes has already taken us on a wild ride. Grab a binocular or a telescope and see this one while you can.

The 7x50 binocular has been the classic astronomy binocular long before binocular astronomy became popular and moved onto the current passion for giant binoculars. In days past, the 7x50 binocular was standard equipment alongside many telescopes and was the preferred instrument for scanning the star fields of the Milky Way and for framing large, extended open clusters and nebulae. A good 7x50 binocular still excels for that application, but binocular astronomy has moved onto applications where a higher magnification is preferred. Still, there will always be a soft spot in my heart for a classic 7x50. Binocular astronomy would not be the same without them.