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Binocular Observing

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clx
clx's picture
Binocular Observing

     Is there on optimum size for binoculars for viewing of variable Stars?  I have three pair of binoculars, 7X50, 15X60 and a pair of  tripod mounted 11X70's.   I ask this in anticipation of acquiring a universal binocular mount for my tripod, and possibly new bino's (Oberwerks 70mm /45 deg or Celestron 25X100).  I might buy these new bino's regardless; they might all be suitable.

     I would like to hear from some seasoned binocular observers on this matter

Aldebaran
Aldebaran's picture
Binocular observing

No, there isn't any optimal size for binocular observing. With smaller bino's you can observe only the brighter stars but with larger, many also fainter stars are well observable for you! The only thing that matters, is that you select suitable stars to your observing program. It's important to not choose too faint stars, because it is very difficult to make any reliable estimates of too faint stars.

Your set of binoculars is really impressive! There are hundreds of stars available with that set of binos! Just use any of the binos, and choose suitable stars for them. Brighter stars for smaller binos, and fainter stars for the larger ones. You can also follow some large-amplitude mira -stars, for example Omi Cet, X Oph or R Aql are well observable with your larger binos also during the minimum of these stars! When these are in their maximum, you can well observe them with the smaller binos. Some small-amplitude semiregular -stars can be observed with one pair of binos throughout their entire cycle. With that arsenal of binoculars, there are huge amount of stars that you can observe, even if you would use only one pair of the binos that you have!

Good observing and clear skies,

Juha Ojanperä (OJMA)

Turku, Finland

pox
pox's picture
Sometimes it's easy to go for

Sometimes it's easy to go for the 'obvious' ones - bright Miras near maximum and so on. But don't forget the unpredictable stars - AB Aur, CH Cyg, AG Dra and (especially with your larger binos) stars like XY Per and CQ Tau which often hover around 9th mag. With a pair of 25 x 100's you'll essentially be a 'telescopic' observer. Even with the smaller sizes you can catch U Gem and SS Cyg near maximum!

mdrapp
mdrapp's picture
It's all about balance

As a beginner I'll give my two cents.....

I find 10x50s an excellent size for binocular variable star observing.  One, while I like to use them mounted, they work just fine for a quick estimate if I need to.  Also, 10x50s tend to have a larger field of view than larger bincoulars, thus making it easier for me to find the field and comparison stars.

--Michael in Houston (RMW)

cutterboyus
cutterboyus's picture
Binocs

As a beginner I had good luck with 10x50s also.  Easy to hand hold and a good field of view to identify variable fields.  Go for quality, you wont be sorry in the long run.  Hard to go below 7.5 mag with my skies though.

lmk
lmk's picture
OK in a pinch

Having done a lot of visual observing with telescopes (mostly) and binos, here's my 2c on the issue:

1. Binos are useful for "grab and go" quick estimates, or when you are travelling or away from your regular telescopes.

2. Given a choice, however, I'd go with even small telescopes (eg. Edmund Astroscan) over binos because:

a. Typical mass produced binos have rather poor optics. If you cannot focus stars to sharp points, you lose quite a bit of fainter star ability (just defocus a good scope and you will quickly lose many tenths to a full magnitude due to the blurring of the image over a wider area).

b. The fixed eyepieces and generally low powers, image distortion from simple achromatic lenses, limit your ability to resolve variables, comp stars from close companions.

c. Holding binoculars over your head and bending your neck backwards at sharp angles gets to be very uncomfortable quickly. Its tough to keep steady as your arms tire. A recliner helps a lot, and binocular stand/mounts are good, but then you are talking about a lot of extra equipment to lug around, even more than a small telescope!

3. Binos have some positive though:

a. Ubiquitous and inexpensive, anybody can buy anywhere and use one.

b. Both eyes in use. Can make viewing more comfortable or natural, BUT only if properly aligned, otherwise a lot of eyestrain negates the advantage.

So, in summary, if you have a choice, get a nice small telescope rather than a pair of binos (unless you already have a pair, and dont want to sell). You will appreciate having something that comfortably points to what you want to see, and stays put without any athletics. Putting binos down to check the chart, and back and forth again to find the field in the sky, is somewhat inconvenient.  Plus, you have choices of great eyepieces to use, such as Naglers and Ethos for stupendous wide views, and various high magnifications!

Mike LMK

BBI
BBI's picture
You can never have enough

You can never have enough binoculars :-). I use a 8x40 handheld for bright stars,12x60 on a long monopod for fainter ones and a 20x80 on a parallelogram. I'm dreaming of a giant ...x100 (45° or 90°) from Oberwerk or Garrett Optical or ? with a sturdy mount like this one "Universal Astronomics Millennium Unimount" (https://www.garrettoptical.com/Universal-Astronomics-Millennium-Unimount-p/ua-01105.htm). No neck pain with this one!

tiburd
There are always tradeoffs; more than one pair is best

Over the past 25 years, I have used many different binoculars in observing, from 7x20 up to 11x80.  Currently I use a 7x35 Nikon wide angle for stars down to about magnitude 7 or 7.5 (or mag 5.5 near a full moon), and a 12x60 Celestron for most non-telescopic fainter stars that I'm following.  Both of these were very reasonably priced and provide superb images.  I still use my 14x70 sometimes, but only rarely; when the 12x60 won't show a target reliably, I often switch to telescope instead.  The 7x35 works surprisingly well, and the 12x60 is a recently acquired instrument that I absolutely love.  I'm very myopic and, when not wearing contact lenses, much prefer to use an instrument that will bring stars into focus without my glasses so I can obtain optimum contrast, light throughput, and shielding from ambient light.  The Nikon and Celestron both do that, but not the 14x70.  Hope this helps...I admire your stable of binoculars and agree with your strategy!

williampme
williampme's picture
Bino observing

I guess I will add my .00022 cents.  I have been observing since 1988 and my best estimate for bino vs telescope observing is 80% bino 20% telescope.  The main reason for this is that I do not use more instrument than I need to get a good estimate.  The vast majority of observations are of M or SRV types and near maximum many of these are mag 8 or brighter.   I have 7x35, 7x50, 10x50, 15x70, and 25/40x100 binoculars.  The 10x50 and larger glasses have parallelogram mounts.  the 7x glasses are for handholding and serve for variables brighter than 6th magnitude.  The parallelogram mount also facilitates zenith observing.  The 15x70 glasses will work down to mag 10 - I can follow Z UMa through it's entire cycle just using these, for example, and have been doing so for years.  The 25x100's will allow reliable estimates to mag 11 or so and the 40x eyepieces down to 11.5.  I have decent but not outstanding observing conditions so the numbers could change if I were in a city or a remote desert.  There are MANY stars within the grasp of 50-70mm glasses, so you could construct an observing list that would keep you busy for the entire year.

LKR
LKR's picture
Binocs and mounts

I've used 10X 50 and 20X 70 but the latter only with a mount. Depends on the situation and the stars I am going for. Both have been good in their respective situations.

 

KL

RJG
RJG's picture
WHICH GIANT BINOCULARS?

I have been observing variables for almost 20 years, always with my (and my wife's) 7x50 OLYMPUS and lately 10x50 MINOLTA.

Now we are willing to expand our coverage to fainter stars and to follow Miras for instance down to 10 or even further, but our budget is very small and have many doubts about which binoculars to buy.

We read reviews about several 20x80 models, but mainly from people that uses them for birds and other daylight targets and even when they comment astronomical observations with these binoculars, the targets are usually the moon and other bright objects. On that issue, people usually say that low budget giant binoculars (like, for instance, BRESSER and CELESTRON) don't give very good images of these astronomical objects.

But what about variables. Are they acceptable to make estimates of variable star magnitudes, for instance, down to 10 or 11?

PLA
PLA's picture
Olá José

Olá José

I have a Celestron 20x80, wich I made my variable star observations. For pratical reasons i do not use it on a tripod, so the magnitude limit is a bit  lower. Under a good sky, abroad Rio de Janeiro city, my limit is 9.0 - 9.2, with the binocular in my hands. On a tripod maybe reach 10 or a bit fainter. The binocular is heavy so in few time my arms become tired. The field of 3° is good. If you are planning to buy such instrument (celestron 20x80), use a good tripod but dont expect to reach much fainter than 10. Until now I dont think I have serious problems with my vision but this is the limit I reach with this binoculars. Um abraço!

RJG
RJG's picture
Olá António

Olá António

Thank you very much for sharing your experience with this model. We have already decided to buy a 15x70 Celestron SkyMaster in Amazon Spain, with tripod and adapter. It will arrive tomorrow and we are looking forward to try it in our Portuguese skies.

Of course, a 20x80 would be better, but for the moment we will have to be content with that model.

I understand that you must go out of Rio de Janeiro to have a decent sky. I have never been in Brazil ("país irmão"/"brother country") but our daughter spent half a year in Rio for her PhD and told us that she hardly saw stars in the sky. Obviously, such a big metropolis (although being "a cidade maravilhosa") must have huge light pollution.

I envy you for being able to see so many constellations - with their variables - that we cannot see from Portugal. We just hardly could made a few observations of T Centaurus but now we cannot reach it from our backyard.

Um grande abraço de Portugal

DFR
DFR's picture
my Meade 11x80 binocs

My favourite for variable observing are Meade 11x80 mm binoculars (mounted) and I find the field of view to be convenient. I have bigger 25x100 Celestron binocs but they are more awkward and bulkier to use. I don't use the 11x80 binocs for lunar or other celestial observing and so the image quality isn't important and I can't comment on it (unless I go and test them the next clear night) but I think they are fine for variable stars. (I originally used them for satellite observing and found them to be great for taking on trips to dark sky sites and observing star fields and clusters in a dark sky.)

Frank

RJG
RJG's picture
Thanks, Frank, for sharing

Thanks, Frank, for sharing your experience with these binoculars.

We, too, don't need an exceptional quality image, as we intend to use them mainly for variable star observing. As we have presently a 10x50, perhaps we will need a big power than yours 11x, to achieve separation of stars that are too close - being doubles or simply close aligned.

That's why we are considering to buy a 15x or even a 20x80.

Another thing: due to a fall, our old 7x50 binoculars - although still working well with terrestrial targets -  now "sees" double stars everywhere, which makes them useless for astronomical observing. Is there a way to fix that trouble?

José

pox
pox's picture
Sounds like a prism has

Sounds like a prism has become misaligned somewhere. Incidentally, something else you might want to consider is observing site. I used to use a 7 x 50 finder on my Dob with which I followed R Vir down to magnitude 10.6, from a dark site. Whatever size bins you use, they should always be mounted in some way. Image-stabilising binoculars I think are overrated (based on experience on Mauna Kea!!)

lmk
lmk's picture
Brrrr

"Image-stabilising binoculars I think are overrated (based on experience on Mauna Kea!!)" - Odd, I would have expected they should have been a blessing up there with all the shivering going on...

 

RJG
RJG's picture
Low-cost giant binoculars

Hi Michael

We (me and Ana Paula, CAI) observe variables from our yard and we live in an urban area in the northern coast of Portugal: light pollution and even frequent summer nighttime fog are our main concerns. In the best nights, magnitude 9 is the ceiling for our 10x50 binoculars.

That's why we are considering to buy something that could gather more light, perhaps with 70 or 80 mm objectives and (we certainly agree with you) in that case it would be unavoidable to use some kind of tripod.

But since we cannot afford the cost of the best models of giant binoculars, we are trying to get some opinions of people that could have used or know about low-cost models, for instance, the 20x80 Celestron Skymaster or Bresser Astro. Were they a reasonable option for someone who simply wants to make magnitude estimates?

José

RJG
RJG's picture
Olá António

Olá António

Thank you very much for sharing your experience with this model. We have already decided to buy a 15x70 Celestron SkyMaster in Amazon Spain, with tripod and adapter. It will arrive tomorrow and we are looking forward to try it in our Portuguese skies.

Of course, a 20x80 would be better, but for the moment we will have to be content with that model.

I understand that you must go out of Rio de Janeiro to have a decent sky. I have never been in Brazil ("país irmão"/"brother country") but our daughter spent half a year in Rio for her PhD and told us that she hardly saw stars in the sky. Obviously, such a big metropolis (although being "a cidade maravilhosa") must have huge light pollution.

I envy you for being able to see so many constellations - with their variables - that we cannot see from Portugal. We just hardly could made a few observations of T Centaurus but now we cannot reach it from our backyard.

Um grande abraço de Portugal

BRJ
BRJ's picture
Binocular Observing

Although this thread began several years back, I'd like to add some of my own thoughts on the subject.

Back in the 1960's I was a very prolific binocular observer with the AAVSO and made countless thousands of observations with my original 10x50 W/A binoculars. I was introduced to this type of observing the AAVSO's all-time champion of binocular observing, the late Edward Oravec. Ed amassed more than 150,000 binocular observations during his long career, always employing rather modest and handheld pairs of binoculars. Ed's favorite in later years was a pair of quality 10x42's.

Over the years I experimented with just about every size of of binoculars, ranging from tiny 3x25 to WWII Japanese 20x120's, gaining a great deal of insight into the performance of aperture vs. magnification. Among the conclusions that I reached in the process has been that binoculars giving an exit-pupil of 4-5mm perform the best under all types of sky conditions. Likewise, handheld use is to be preferred over having them mounted, noting that extended practice at holding them steadily is a great benefit to the observer. When at all possible, work from a seated position, especially if you can support your arms and perhaps rest you head when viewing with the binoculars. Using binoculars and while still using great care to accurately estimating the variable, it is possible to cover a large number of different stars over the course of say an hour's observation. Ed Oravec and I often could estimate 45 or more stars over that interval of time. And a final huge advantage to those without a permanent observatory, binoculars need no set-up time. You just walk outside and you are ready to go! This can prove exceedingly valuable should you get unexpectedly clearing skies that may last only a short time. And finally, at least at the outset, include a selection of Miras together with more typical, smaller range SR and Ir stars to your program. The former will offer the opportunity for you to compare your estimates against those of a large number of other observers to check your accuracy, the SR and Ir stars often having far less observer coverage and greater scatter.

My own workhorse binoculars for VSO today are a pair of 10x50 W/A and a pair of 15x70's. Back in my early days my totally un-light polluted skies allowed the former pair to seeing deep into the 11's, while my mounted 20x120's reached well into the 13's on the best nights.

J.Bortle (BRJ)

 

 

 

 

lmk
lmk's picture
Convenient but don't work well.

"And a final huge advantage to those without a permanent observatory, binoculars need no set-up time. You just walk outside and you are ready to go! This can prove exceedingly valuable should you get unexpectedly clearing skies that may last only a short time."

My 16.5" f/2.9 Newtonian works just like that in my cloudy windward Hawaii climate, but gets to mag 16... :)

Typical commercial binoculars have poor optical quality - they use cheap cemented spherical achromatic objectives. And fixed, low power eyepieces. This eliminates the ability to use higher magnification under bright conditions, such as the full moon, to retain ability to follow your fainter objects. Also, the low power and relatively (to telescopes) poor image quality makes it impossible to separate variables from close companions, potential erroneous measurements.

Of course, you can obtain expensive image stabilised and apochromatic binoculars, but they will cost over $1000 or much more. For that kind of money you can get a very potent goto Newtonian, SCT, etc.

This is not to say commercial binoculars are totally useless, they can be effective for bright variables, in clear fields without confounding close companions, as well as estimating brighter comets. Yet, my compact 16.5" is so versatile, can be used to estimate 7 magnitude variables as well, by very low power and defocus, putting it all in perspective here...

Mike

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