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What size binoculars do you like?

SET's picture
Joined: 2010-07-23


Those of you that observe binocular variables, what size of binoculars do you particularly like? I really like my 10X50 Wind Rivers. I have used 7X50's with good results, but like that extra power. I find that anything above 10X50 needs a tripod. I just shake to much. I used to use 15X70's, and I really had to prop them against my body or put my elbows on the arms of my lawn chair. I sold my 25X100's and parallelogram mount. They were great, but just to much hassle to set up.

Sebastian Otero is a binocular user. Sebastian, what size do you like, or do you use a variety of sizes?


Chris Stephan   SET

Robert Clyde Observatory

Sebring, Florida  USA

PKV's picture
Joined: 2010-07-26

My favorite binoculars are my Fujinon FMT-SX 7x50's.  The field is generous at 7.5 degrees.  I do only a few binocular variables: Rho CAS, R SCT, W ORI, P CYG and others due to bright skies here in northern Houston.  Kevin  - PKV

I use my 8x40 Helios
BBI's picture
Joined: 2011-03-08

I use my 8x40 Helios Naturesport most. It wasn't expensive and has a 8.2° wide angle. I use a handy monopod with my 10x50, a parallelogram mount with my 20x80 and a tripod for my 25x100. The bigger the bino, the less I use it! A 8x40 is just "fast", to make quick observations between the clouds or in the summer when it's dark, late in the evening.


What size binoculars do you like?
wlm's picture
Joined: 2010-07-23

When I was observing, I used three different binoculars, all to good effect. A pair of 7X50 Sears binoculars got me started, but I upgraded to a larger binocular, 9X63, and used those for a number of years and loved them. When the 9X63  pair was stolen, the insurance company replaced them with a pair of Nikon 10X70's which are good, but heavier. I can sympathize with your problems hand holding anything much larger than the 7X50's.

Back to the 9X63's which I consider the ideal for vsoing. During WWII, the need existed for binoculars with larger apertures to be used by bombadiers on bombing missions. Bausch & Lomb, who manufactured large numbers of the 7X50's for other military applications, produced the 9X63 by screwing extension tubes into their usual 7X50 units in place of the 50mm objectives, and added the 63mm objectives at the slightly longer focal length. The combination produces the same exit pupil, best for dark night skies but perhaps not so great in urban or nearby suburban areas. The weight of binoculars is for the most part in the prisms and focusing mechanism, so the change in objective diameter had very little effect on the overall weight or balance of the binoculars. You will occassionally see a pair of the WWII B&L 9X63's for sale and if you can find those I highly recommend them for vsoing.

20x60B Tento
FRF's picture
Joined: 2010-08-09

I've purchased a 20x60B russian (Tento) binoculars around 20 years ago, when it was very popular among Hungarian observers. This is perfect for variable stars. I use it without tripod. Nowadays several of my friends who observe variables use 15x70B (Skywatcher?). It is much lighter then the old russian 20x60B, but smaller magnification.

My 20x60B is perfect for variables in the range of 7-10th magnitude (even from the light polluted Budapest).

Sebastian Otero
Sebastian Otero's picture
Joined: 2010-09-19

Hi, Chris,

I use 7x50 Pentax binoculars. Those are the only ones I own and I like them, they are luminous. In the best nights (like last night) I get to a limitting magnitude of 9.0 from the city. I don't have a mount, I always observe resting my arms on the arms of my lawn chair. I couldn't observe in any other way without a mount. I have tried 10x50s but I didn't like the darker background and the fact that I couldn't get the image steady due to the larger magnification. They are more comfortable to sweep Milky Way fields and general observing but didn't find it appealing for variable star observing.


Re: Binoculars
GKI's picture
Joined: 2010-07-24

Hi all, I like to use my astrophysics 15x70 binos, they are great quality but a little heavy to hand hold and are amazing for the brighter variables. Also sometimes I like to use mt 20x90's on my parrallelogram mount which doesn't take too much time to set up, on a good night they can get me down to magnitude 11.5 :)

Nova patrol is my thing, but I find that although you can memomize starfields, I am thinking about going over to DSLR imaging instead, although with my binoculars, I love that 'live' view feeling.


Favorite binoculars
sdn's picture
Joined: 2010-07-23

I enjoy my Orion 15x70 binoculars for visual variable star estimates, solar observing, lunar observing, and deep-sky observing.   I mount them on a Bogen tripod.  The entire setup is sturdy and quite portable.

Regards, Doug

Image stabilized binoculars
BTB's picture
Joined: 2010-07-23

I use Orion 10x50 binoculars but have a hard time holding them steady. I gave Canon 10x30 IS binoculars to my wife primarily for bird watching, and was amazed by how well the image stabilization works. I tried them on the stars and was equally impressed. The steady view goes along way towards making up for the lack of aperture. Has anyone had a chance to use larger Canon IS binoculars? Unfortunately they are very pricey.

Choice of Binoculars
BRJ's picture
Joined: 2010-07-24

As someone with a long, long history of employing binoculars for the observation of variable stars (and comets), particularly so in my early AAVSO years, I always highly preferred 10x50 WA binoculars. When I first moved to my rural home some 4 decades ago these binoculars were quite capable of allowing estimates as faint as the mid 11's without difficulty. Needless to say, urban sprawl since then has steadily reduced their ability and today my choice has become a pair of 15x70 binoculars, which I still generally hand hold during observing.

Early in my observing career with the AAVSO I was mentored by the organization's premier binocular observer, Edward Oravec. One especially valuable lesson he passed on to me was that the best choice in a pair of binoculars for variable star observing was one affording a 4mm or 5mm exit pupil, not one with 6-7mm. This, he pointed out, was particularly true in the case of urban and suburban observing situations, something that has today become almost universal for AAVSO observers. Ed's longtime choice in binoculars was a pair of 10x42's. With those he made more than 150,000 estimates.

Except in a truly dark location the pupil of the eye never fully opens beyond 5mm, or possibly 6mm in the case of the very young. For older observers like myself, even at a dark site the pupil likely never exceeds the former value when it is opened to its maximum. Obviously then, if the exit pupil of the binoculars is 7mm, and the opening of the eye only 5mm, then you are essentially reducing significantly the relative aperture of the instrument, wasting light and limiting your magnitude threshold. The sky background darkening effect with increasing magnification, along with the greater separation of the comp stars in congested fields, are also advantages not to be overlooked.

J.Bortle   (BRJ) 

TYS's picture
Joined: 2010-07-28

My favorite binoculars for VSOing are my Orion 12x63's. They give a large enough FOV and I can still hand hold them and I gain about a magnitude over my 10x50's.

Rich Tyson (TYS)

Canon 15x50
potterrb's picture
Joined: 2010-08-06

I have used Canon 15x50IS binocs for years, both for VSO and general observing.  As John points out, exit pupil is important.  The exit pupil, 15x magnification, and 4.5 deg FOV make these binocs wonderful if you can afford them.  I sold my first pair to raise money for another project, but could never find less expensive binocs that I liked nearly as well so I ended up buying another pair and will never let them go.

If you can afford them, they're the bomb!

ajc's picture
Joined: 2010-11-26


I prefer a 15x60 to offer a better contrast in cities with high light pollution. I do not use mount, only my arms. I use a 7x35 for stars brighter and larger fields.

João Marcos, Brasil

lmk's picture
Joined: 2010-07-23

Well, I just thought to drop my 2c worth here. I am not a big bino VSOer. I use principally large aperture Newtonian reflectors (even so for the brighter variables, just using very low power). But, I have used 7x35, 7x50, 10x50, 20x100 in the past. I would say the 10x50 probably the best overall between what you can resolve vs. comfort holding them. But, holding anything with your arms raised gets tiring quickly!

When folks talk about binos, I presume they mean the traditional ones with fixed eyepieces built in, as opposed to bino-telescopes. The main problem which turns me off from the fixed ep binos is the low power and poor optical quality, compared to real telescopes. Even expensive ones have optical/chromatic defects which prevent focussing stars to perfect pinpoints. This can be a problem when trying to resolve variables from close cpmpanions, or observing in dense star fields near the Milky Way. The fuzzy optics tends to smear the stars together into a messy mass. I just prefer to see things perfectly sharp and clear. So, I shun these type of binos.

Bino-telescopes are really cool, though. Observing perfectly sharply with both eyes at any chosen magnification is truly glorious! But the inconvenience of their size, observing positions, and collimation headaches makes them not so practical for everyday use. But they are a treat to check out at a dark sky party :)

Mike LMK

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484