An astronomy club member asked me recently what kind of binoculars should they get to use for astronomy. The question is dependent on what you want to observe, but as a general purpose binocular that can be used with moderate power and give good bright views, 10 by 50 binoculars are difficult to beat.
**** I'd suggest the vixen ascot 10 by 50 binoculars.***** more details follow.
7 by 35 binoculars are lighter and better for young viewers if they are in a dark sky, because they may use them for other general purpose use a 7 by 35 used to be preferred by young folks. But the person who asked me is a "grown up" and in college. Also binoculars that are more powerful will show more detail, but just a little more in most cases or in viewing the moon.
In the case of planets you'll see the rings of Saturn better with 20 power or greater. But there's not a lot of detail regarding rings of Saturn, 20 power won't show much. And you're going to give up hand held convenience for 20x binoculars to see a very small ring around Saturn. It's probably not worth it. I'd suggest going for lower power than 20x for the added convenience of hand held use.
Since your not going to see planetary details and binoculars are great for sweeping views, it's almost silly to get a high powered pair of binoculars, especially as your first pair. You can add other specialized binoculars or telescopes to your inventory later. With high power you can't see a wide field of view which is the chief strength of binoculars and you can't use high powered binoculars hand held either. (A 20 power binocular cannot be used without a mount.) With a mount your starting to do telescope like setups and that takes more time. If your going to use a mount, you might as well have a telescope, so don't buy a first set of binoculars that requires a mount. That defeats the purpose of getting them to begin with.
Also consider this. I have BT-80 binoculars by Vixen, they weigh 12 lbs and require a very strong mount. I have a $300 heavy duty camera mount for them and it's not strong enough. They require a better mount. I often use these with 25mm eyepieces and this gives 36 power. 36 power doesn't show much detail in Jupiter or much of the rings of Saturn. You can see little detail even at 36 power. 48 power shows a little more but is still quite low. It sometimes appears to be twice the power, due to illusion factors due to stereo vision, but still the details are not present even with 50x. I'm often wanting to move to a telescope to see details even when using 48 power with my Vixen BT-80 binocular telescope. If I want to see more with 50x, you're going to wish for more with 20x binoculars. So don't be fooled into thinking 20x binoculars will replace a telescope or give tons of great views of planets. Binoculars need to be very specialized and mounted like telescopes to give good planetary views. I can get decent views at high power of planets, but my alignment is often a bit off, and I have manual adjustments to align my telescope with high powered eyepieces. That's another story. The Vixen Bt80 binoculars I purchased cost me $800 and the eyepieces I use have to be purchased in pairs. TV plossls cost $100 to $150 an eyepiece, so with three or four powers I'm spending almost as much as my binoculars on the eyepieces as well. If my $1500 binocular setup doesn't satisfy my planetary needs, a 20x pair of binoculars will not meet your planetary needs. Binoculars with higher power will show better lunar detail. A 20 or 25 power binocular for the moon is a wonderful thing. I like the moon at 36 power in the Vixen binoculars. A pretty nice view. At 48 power, the view is even better, but with narrow field binoculars I have to keep moving the binoculars on the mount as the moon slips out of view quicker at higher powers. All this conversation is meant to go back to the basic reasons people get binoculars. We get them most of the time in astronomy to get wide field views. So get that covered with your first purchase. Start with 10 by 50.
So your first pair should be some what powerful, have some power and some light gathering power, but not to much power and not very heavy. Some astronomers get large aperture binoculars which is a good idea, because you'll see more deep space objects, but you cannot handhold a 10 by 80 binocular and even 10 by 63 binoculars look huge. We are left with a compromise for astronomy.
But don't compromise in quality, if you can afford quality. If you buy cheap stuff, you'll end up spending more money again to replace the cheap stuff, so you might as well get the good stuff to begin with.
There are some makers that make really nice quality binoculars, Celestron, Vixen, Nikon and others. Vixen makes some of the Orion binoculars who rebrands them. There are a lot of good binoculars and when your looking at them you may be tempted to get the most features offered, but this is a mistake for astronomy.
Extra features to avoid with your first pair:
Zoom binoculars for example seem like a great idea and they may work okay for some uses, but not often for astronomy. Rubberized tough and waterproof binoculars seem to be good features, but these often add weight: they are okay for hunting, but not for astronomy, because with astronomy you will be holding the binoculars up in the air looking up at times with extreme angles. Every bit of weight adds to the strain and you'll want the lightest quality binocular you can get, not a rubberized militarized binocular that weighs a ton.
Some brands seem nice at local sporting goods stores, but when you take them out to do astronomy you will find the quality suffers and they have optics that are cheap. Affordable doesn't mean you will be able to use many of these, so I'd avoid some of these cheap sporting goods store made in China binoculars. Some older binoculars that were cheap could have good optics, for example some early kmart binoculars made in Japan might have good optics in the old days. They were cheap but had good optics. But much of the cheap Chinese binoculars made today sold super cheap have junk optics compared to japanese optics or German optics. Some companies had good optics for a while but later the brand shifted to cheap production. You might find good used binoculars of a brand name, that later may have shifted to cheaper models. So there is a lot of variation.
There are some common astronomy brand binoculars that are pretty good. There are also specialty Japanese or German brands that re quite good.
For astronomy I'm not going to list all the good brands, just a few and mention one that I would suggest today. Celestron makes some nice binoculars, often 7 by 63, 10 by 63 and 15 by 63mm binoculars are offered and purchased by astronomers. But these are often to heavy for handheld use. Some larger guys might handhold the lower powered ones, but for extended viewing they will often use a tripod or a monopod. Perhaps they are okay for a quick view, but not that usable for extended handheld use. Many end up with more than one binocular, more powerful ones on tripods and lighter low powered ones for scanning the skies. Ken in our club owns many binoculars and even uses some 3 powered opera glasses, which is another subject. If your getting your binoculars as a gift, maybe a good strategy is to get the good higher priced, higher powered binoculars first and later purchase the low powered small ones. Of course this depends on how much of a budget your gift would be limited to.
10 by 50 are likely the best compromise, but one with quality.
If your looking for a good quality pair of binoculars, I'm going to suggest the vixen Ascot wide field 10 by 50 binoculars, which list for 179.00. Opt telescopes sells them for $169.00 on sale right now. These are pretty nice, spec wise. They offer an 8 degree field of view and weigh only 2 lbs.
There are other nice binoculars out there. And some may have a lot of quality. For example I saw a pair of Nikon zoom binoculars that were 8 to 22 power. Nikon is a good name, I don't know about the quality of those binoculars, and zoom seems nice, but consider this, a zoom binocular has a Barlow lens inside and the widest field of view at the lowest power for that Nikon zoom binocular is 4 degrees. Tonight I looked at Venus and the crescent moon. I briefly looked at them through my old 10 by 50 Kmart binoculars which have an 8 degree field of view, and then I looked at the moon and Venus with my f4 four inch homebuilt telescope. The f4 four inch telescope is practically the widest field of view optical telescope one could use.
I could easily see the moon and Venus with my kmart 10 by 50 binoculars because there was only about four degrees of space between those. They fit easily inside the 10 power binoculars. With my f4 wide field telescope an a 40mm eyepiece, I could only see four degrees of view and that was not enough to see both the crescent moon and Venus in one field of view. So my old kmart binoculars beat my telescope when looking at this wide field wonder happening. The vixen Ascot and many other wide field binoculars could show both of them as well.
A zoom binocular would offer narrow field of views. The 8 to 22 power zoom binoculars by Nikon have only a 4 degree field of view, so it's likely that we would not see both objects tonight with the zoom binoculars. At 8 power we'd see half the sky we'd see with the 10 by 50 binoculars, so is that zoom optical eyepiece worth half the field of view that a 10x50 would give? Most would say, no. Zoom binoculars also add more glass and that can reduce the quality or perhaps cause the edge of the field of view to be out of focus, like a cheap spotting scope would perform. Some spotting scopes seem to be good astronomy items to own for beginners and they can be. But many spotting scopes offer narrow fields of view, due to the internal barlow and are not really sharp out to the edge of the field of view. They are good enough for widelife, but not very great for astronomy. Perhaps as much as the outer 20 or 30 percent will be out of focus as far as looking at stars with many spotting scopes that are on the market.
So the overall suggestion is find a light high quality optic, well aligned and for wide field use. After all it's about wide field. You can use a low powered rich field telescope for wide field astronomy with a tripod. The binoculars, at least your first ones should be grab and go hand held, wide field sweepers. A great advantage to binoculars, is that like spotting scopes everything is right side up, not inverted image. so binoculars are great for beginners and really for anyone to sweep the sky and see a lot in a hurry.
CONCLUSION - For a quick suggestion.
I'd suggest the vixen ascot 10 by 50 binoculars. The main reason is another member in the club purchased these recently and was happy with them and he owns five or six binoculars already.
There are other quality brands of binoculars. Some brands that used to be quality are not as good and sell cheaper binoculars. Bushnell being one example. I would avoid new Bushnell binoculars, they used to be good quality mid priced. Barska binoculars also seem to be very affordable, but seem to me to be very cheap with the quality of views they give, I'd avoid them and local sporting goods stores stock tons of these. I suspect it's because they are very cheaply made and there is a high markup.
It seems nowadays you need to spend over $100 for quality binoculars for astronomy use. If you look for used. Binoculars you may end up with junk because they are often abused and are out of alignment due to abusive past owners. In writing this I actually thought about those old 7 by 35 kmart binoculars I had as a kid. I know they aren't the best binocular for astronomy, but they may have a place for dark sky viewing and for kids who are small and they may be more convenient for longer handheld use. I know I always wished when I was young I would have gotten an exact replacement for the 7 by 35 binoculars because I liked the long term use I could have with lighter binoculars. Thinking about this and because I have some 10 by 50 binoculars already, I took a risk and bought a used pair of kmart 7 by 35 binoculars to round out my inventory of binoculars. You can never have to many binoculars and telescopes, at least until you run out of storage. I didn't spend to much money for the used eBay binoculars, and hopefully they are not damaged and out of alignment. There's always a risk when buying used.
Right now I have vixen BT-80m binoculars which are huge, narrow field telescope like binoculars. They are fun and those and my 10 by 50 binoculars round out my inventory. I had a fun time tonight spending only 15 minutes outside looking at the moon, Venus, Jupiter and mars. I only looked at these with my Binoculars, both the BT80s and the 10 by 50, and then used my f4 four inch homebuilt telescope as a handheld telescope with a low powered telescope. I looked at a few objects with three instruments in under 15 minutes. That's a fast quick astronomy fix, and binoculars and simple or no mounts makes that possible. It's really difficult to beat grab and go setups. Binoculars are often overlooked in astronomy. I'd suggest getting a pair and having it close by, perhaps in your car so you can grab them whenever you need them.
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