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Terrestrial vs. Astronomical Binoculars?


Hayduke27

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Before I got into astronomy recently, I had already been into other hobbies (including birdwatching and hunting) for which I needed optics.  Over the years I acquired some decent binoculars and a good spotting scope.  The binoculars work absolutely great for terrestrial uses, and so far as I can tell they are working very well for stargazing.  I was wondering if there is a functional difference between binos designed more for terrestrial viewing vs. those designed for astronomy? 

 

I understand that astro binos might likely have more aperture, and that terrestrial binos are often designed with portability in mind, and therefore smaller size and less aperture.  I was more curious as to whether the astro binos have anything in the inner workings that make them superior for stargazing to those specifically designed for terrestrial use?

 

The ones I have are Vortex Viper HD 8x42, and they work great for looking at the stars so far as I can tell.  I bring them with me every time I go out!

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No such thing as binoculars for only stargazing...Binoculars are bionoculars, no different functionally.... some shops might sell "astronomical" binos with a inflated price, but essentially they are identical.

 

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For handheld, lower magnifications work better as it is easier to hold them steady. The 8x42 you have are ideal for this as you will have found. I use a pair of this spec and love the widefield views it gives.

Other options might be 7x50 or 10x50. The largest that people generally handhold are 15x70s which give more light grasp but even these might be better mounted on a tripod.

Beyond that you are into say 20x80 or 25x100, much larger aperture, higher mag and definitely requiring a solid mounting.

I've also used Canon 15x50is stabilised binoculars which work very well, giving higher mag but a nice stable handheld image. Expensive but fun.

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Stick with the Vipers, they will do everything you want.

Many "astronomical" binoculars seem bigger terrestrial ones and to my thinking do not really fit the description. They have bigger apertures so collect more light, but they also have bigger magnifications so reduce the brightness, in astronomy if one set says 10x and another 20x people buy the 20x. They are however bigger and heavier and for stability need a tripod or monopod to use them.

I keep seeing "More aperture" and "More magnification" but magnification counters aperture, and more aperture on what are 2 fast achro "scopes" mean more CA.

I would say these are Astronomical Binoculars from TS, :eek::eek::eek:

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If you have much light pollution of your night skies you will probably be better off with a slightly higher magnification as this will improve contrast (make the background sky look darker, and so make fainter objects easier to detect)..

That's why, for example, 10x50s are generally preferred to 7x50s..but in a dark sky your eye can better use the larger exit pupil of the lower magnification pair. (Exit pupil is aperture divided by magnification, so 7x50s have a 7mm exit pupil and 10x50s have a 5mm exit pupil).

Most healthy adults eyes have a maximum dilation of the eye's pupil of c7mm, in very dark environments, while light pollution might mean your eye only dilates to 4 or 5mm. In addition, as you get older your eye's maximum dilation reduces a bit too.

Your Vipers, at 8x42mm will deliver just over 5mm exit pupil, making them an ideal all purpose binocular for astro use?.

Dave

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(Only responding because Steve (@steppenwolf) tagged me; nothing substantive to add. :D)

The Vortex Viper is a lovely binocular; very good optical quality and very robust (it is favoured by some South African game rangers precisely because of those qualities). As others have indicated, if it ain't broke, no need to fix it.

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The only other relevant difference I've found between different binos is how good the internal baffling is. This is only really an issue when viewing the moon, some binos give horrible internal reflections which are not really an issue during the day, others give a good clean image with a nice dark background.

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It's possible to DIY binoculars specifically for astro use, either angled as in the photo or just straight through with no prisms which adds to the light loss and expence. The main requirement being that no diameter is greater than your IPD.

IMG_9272.JPG

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When I bought my Vanguard Endeavor II 10x42s I had a very very close look at the Vortex Viper, and couldn't really decide between them as they were so closely matched. Ultimately it came down to the cost, and the Vanguard's are a lot cheaper in the UK than the Viper's. I've been extremely impressed by how much those relatively small lenses can pick up in the night sky, and I'd imagine your binoculars will match them. The Vipers are an excellent piece of kit, with quality optics, ED glass, very high light transmission, and a true aperture of 42mm unlike cheaper models which say 42mm but are actually somewhat less.

"Astronomical binocular" really just means a normal binocular with very large lenses. Nominally a 50mm aperture would show you more, but with the quality of your lenses and the coatings on them I doubt you'd see any improvement unless you bought a 50mm of equivalent quality. Then there's 70, 80 and 100mm apertures, and they will certainly show a lot more, but this gets us into the realms of handshake and the need for tripods. These big binoculars have many benefits but come with a degree of inconvenience which you'll never have with a simple and pretty powerful pair of 8x42s in your pocket.

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My 16x70 Fujinon proved brighter and sharper than a couple pairs of low-grade 80mm someone brought to the observing field. Didn't happen often but the memory is vivid. A russian 20x60 Tento that was always hanging at the observatory's wall for everyone to use seemed like it was more than 10mm smaller.

The extra magnification is supposed to darken the background (which is really the foreground but I'll speak as everyone does), and it did, but the stars were still disappointingly dim cause the optics couldn't do better. Aperture rules but clarity wins.

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On 02/12/2017 at 18:22, Hayduke27 said:

The ones I have are Vortex Viper HD 8x42, and they work great for looking at the stars

......and nothing wrong with them either! My favourites are the Helios nature sport 8x40's, perfect for wide views , and anything with more magnification requires more steadying?
I'll  mount any binocular to get the benefit of a rock steady view and sharp image.

I don't expect to see planetary details, and stars will only ever be single points of light, therefore my grab & go binoculars, inevitably are the 8x40's.

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Some care is needed in regard to large aperture binoculars. It is very easy to add lots of aperture but you will also add lots of exit pupil if the magnification remains low and the additional light won't pass into your eye. (I had some Celestron 11x80 Comet Hunters. They looked very impressive and weren't bad, but the exit pupil of 7.2mm was certainly too large for my eyes. I found I had as bright an image in 15x70.)

Once you increase the magnification to bring down the exit pupil you move away from anything hand held. At this point I think it's perfectly fair to talk about 'astronomical binoculars' which might also have angled EPs for looking comfortably skywards. Also marine and astronomical binoculars will be used close to infinity so having individual focus on each side is no detriment. It would drive me frantic for terrestrial use though.

I like hand held binos for astronomy since I have telescopes for high power. I'm happy with 8x42.

Olly

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9 minutes ago, BinocularSky said:

Yes, same ones. (But the individual focus would likely dement you ...:D )

Vixens, Out of my price league at present but will read your report later at work, just printing now!

As for Individual Focusing, I love the idea, but some folk will hate them.
I've even used fixed focus for many Years, just as effective if the depth of field is adequate.
On a side note, I  know my Strathspeys are basic, but once the IF is set, there's nothing  left to twiddle with for  the whole session, great for gloved hands on a cold night?

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On 04/12/2017 at 11:55, BinocularSky said:

Just to add: my new favourite hand-held astronomy binocs are Vixen 6.5x32. Nice flat unvignetted 9 deg field! The 2.1x42 is also lovely, especially from a dark site.

Just read your review of these, Steve, they sound like an excellent middle ground between the vixen 2.1x42 and regularly compact binos such 8x42's. "I used to think a little gem was a lettuce" - that did make me chuckle. 

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1 hour ago, Lockie said:

Just read your review of these, Steve, they sound like an excellent middle ground between the vixen 2.1x42 and regularly compact binos such 8x42's. "I used to think a little gem was a lettuce" - that did make me chuckle. 

Steve kindly passed my the Vixens one night and they were just lovely, light to hold and steady also because of the low power. The field was huge and the contrast as crisp as you like.

Olly

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If you are willing to cough the cash - these are absolutely brilliant.

The Image Stabilization has to be seen to be believed. It's like they are on a tripod!

https://store.canon.co.uk/canon-10x42l-is-wp-binoculars/0155B010/?nav=binoculars

But very, very expensive. I bought mine in a dash of impulsiveness. Totally crazy! But I am glad I did. :icon_biggrin: 

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3 hours ago, ian_bird said:

The Image Stabilization has to be seen to be believed. It's like they are on a tripod!

When I'm at my scope, my Helios 8x40s are hung around my neck, but for almost every other time their used, I  generally mount them using a tripod and trigger grip. Silky smooth to operate, yet rock steady, providing perfect images, great for my needs, all at fraction of the cost.

I have used image stabilised  binoculars, think they were Nikon's. but still trying to verify this? though they were essential  only used from a moving platform, where a tripod would be totally inadequate!

 

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15 hours ago, ian_bird said:

If you are willing to cough the cash - these are absolutely brilliant.

https://store.canon.co.uk/canon-10x42l-is-wp-binoculars/0155B010/?nav=binoculars

Or, if you're on a slightly (for tiny values of "slightly") tighter budget, these are interesting. Standard IS for panning, powered IS once you have acquired your target.
https://store.canon.co.uk/canon-14x32-is-binoculars/1374C005/?nav=binoculars

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Astronomical binoculars tend to be porro rather than roof prism. 

Porros are bulkier & often heavier but give wider fields of view - 7x50 standard is 7 degrees for a porro prism pair. 

Roof prisms bins absolutely need ED lenses & better prisms due to their optical design. 

Any bins with anti-fog/haze is excellent for either land, sea or sky viewing. Marine bins are best, usually 7x50 or 10x50. They allow steadier viewing and are coated to allow high light transmission for their main purpose. Being for use on the water, they are submersion proof rather than shower proof. 

For terrestial, centre focusing is more user friendly, especially for wildlife. Binoculars for greater distance such as astronomical or greater ruggedness like marine models often have individual eyepiece focusing. I have had a centre focus pair freeze up in its centre column on sub zero nights, but not any pair that only has turning eyepieces. 

 

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