20 x 80mm Astro binocular

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The Meade 20 x 80mm Astro binocular offers the equivalent light gathering capacity of two 3.1” rich field refractor telescopes – one for each eye – to provide bright wide field views of large and faint deep space objects. Using two eyes to observe increases the resolution of small details by as much as 40% over the resolution visible when using only one eye, as you do when looking through the single eyepiece of a telescope or spotting scope.

While the Meade 80mm Astro offers admirable wide field astronomical viewing on its own, it also serves as a good wide-field observing complement to the narrower field of a telescope. You can sweep the skies for objects of interest before going in for a close-up with your telescope. It’s a great grab and go instrument for a quick peek at the sky when you don’t have time to set up your telescope. And one person can use the binocular while another uses the telescope, doubling your observing enjoyment.

At a little over four and a half pounds, the Meade 20 x 80mm Astro binocular is realistically too heavy to hand hold for any length of time, so a tripod adapter is built into the binocular to take its weight off your hands and wrists. Using the Meade 80mm binocular on a tripod is virtually mandatory, as few people will have the wrist strength needed to hold them steady enough for extended hand held use.

A reinforcing bar runs from the prism housings to the objective lenses. In addition to providing structural rigidity that keeps the optics firmly collimated, the bar provides a sturdy support for the integrated tripod adapter. The tripod adapter can slide along the bar to balance the binocular on your photo tripod, no matter what part of the sky you are viewing. Once you find the correct balance, a large hand-tighten knob locks the adapter in place.

The 20 x 80mm Meade uses high light transmission BaK-4 prisms and multicoated optics for bright images of faint deep space objects. With a good 3.2° field of view, the Meade excels at sweeping the star clouds of Sagittarius, searching out the Great Galaxy in Andromeda, taking in open clusters like the Beehive and the Wild Duck, and much more. There is some minor barrel distortion (straight lines at the edge of the field are curved), and some visible astigmatism and chromatic aberration at the edges of the field. However, these flaws are minor considering the Meade Astro’s aperture and price and are unobtrusive for all but the most critical and nitpicky of observers.

Eye relief is specified at a good 17mm. While this is technically correct, the actual usable eye relief typically measures a few mm less due to the recessing of the eyepieces when the eyecups are rolled down for eyeglass use. A shorter eye relief than specified is typical of all binoculars. There will be some minor vignetting of the field for those who must wear eyeglasses while observing.

Soft roll-down eyecups shield the unaided eye from stray light when rolled up, and cushion eyeglass lenses when rolled down. The prism housings are lightly armored to protect against bumps and shocks. A padded nylon carrying/storage case is standard equipment, as are protective snap=in lens caps and an eyepiece rainguard.

The Astro is designed strictly as a long-distance observing tool from a tripod-mounted fixed location. With a close focus of nearly 100 feet, The Meade 20 x 80mm is not a general-purpose binocular. That said, the Astro is a good choice for long distance terrestrial viewing under low light conditions. Nesting eagles or ducks across a lake at dusk are prime candidates for this big binocular. As a first serious astronomical observing tool, as a long distance nature study instrument, or as a highly useful companion to take into the field with your telescope at night, the Meade 20 x 80mm Astro is a worthwhile balance of performance versus price.

Optical Type:
The optical design of a binocular or spotting scope. A binocular can be either a porro prism (whose objective lenses are off-set and spaced further apart than the eyepieces) or a roof prism (whose objective lenses are in line with the eyepieces). A spotting scope can be either a porro prism or roof prism refractor or a catadioptric (a combination of lenses, mirrors, and prisms).
Porro Prism
Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
3.2°
Field of view 1000 yards:
168'
Exit Pupil:
The circular image or beam of light formed by the eyepiece of a telescope. To take full advantage of a scope's light-gathering capacity, the diameter of an eyepiece exit pupil should be no larger than the 7mm diameter of your eye's dark-adapted pupil, so that all of the light collected by the telescope enters your eye. (The eyepiece exit pupil diameter is found by dividing the eyepiece focal length by the telescope focal ratio.) Your eye's ability to dilate declines with increasing age (to a dark-adapted pupil of about 5mm by age 50 or so). For those in this age group, eyepieces with exit pupils larger than their eyes can dilate to simply waste their telescope's light-gathering capacity, as some of the scope's light will fall on their iris instead of entering their eye.
4mm
Relative Brightness:
A number used to compare the brightness of binoculars or spotting scopes of similar magnification. The relative brightness is determined by squaring the diameter of the exit pupil. The larger the relative brightness number, the brighter the image.
16
Twilight Factor:
A number used to compare the effectiveness of binoculars or spotting scopes used in low light. The twilight factor is found by multiplying the size of the objective lens (in mm) by the magnification and then finding the square root of that result. The larger the twilight factor, the more detail you can see in low light. A twilight factor of 17 or better if usually required for reasonable low light use.
40
Eye Relief:
Eye relief is the distance from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the circular image is formed, sometimes called the “Ramsden Disk.” This is where your eye should be positioned to see the full field of view of the eyepiece. If you must wear glasses because of astigmatism, you’ll usually need at least 15mm of eye relief or longer if you want to see the full field of view with your glasses on.

A note on our eye relief figures: Quite often, our eye relief figures will differ from those of the manufacturer. This is because we measure the “usable” eye relief, while the manufacturers specify their usually-longer (but technically correct) “designed” eye relief.

The eye lens of the eyepiece is normally recessed below the rubber eyeguard or rubber rim of the eyepiece to keep the lens from being scratched during use. An eyepiece might have a “designed” eye relief of 15mm (and the eye relief will truly measure 15mm from the eye lens to where the image forms). However, if the eye lens is recessed 3mm below the eye guard, the Ramsden Disk forms only 12mm above the eyepiece body (the 15mm “designed” eye relief, less the 3mm of eye relief made unusable by having the eye lens recessed into the body of the eyepiece). This “usable” eye relief of 12mm (measured from the rolled-down eyeguard – the closest point you can get your eye to the eye lens – to where the image forms) is the eye relief figure we would measure and list in this website.

Why is it important to list the “usable” eye relief? For those people who don’t wear eyeglasses while observing, a few mm difference between the eye relief they expect from the manufacturer’s literature and the shorter eye relief they actually get in real life doesn’t mean a lot. They can simply move a little closer to the eyepiece to see the full field, and never realize that the eye relief is a little shorter than they expected. However, some people must wear eyeglasses while observing, because of severe astigmatism. These observers can’t move closer to the eyepiece if the eye relief is shorter than expected because their glasses get in the way. For these people, the real life “usable” eye relief is more important than the technically correct but sometimes not fully usable “designed” eye relief. We measure and list the actual usable eye relief so that people in the real world can pick the eyepieces that will work best for them.

17mm
Interpupillary Distance:
58-72mm
Close Focus:
How close you can get to an object and still see a sharp image of it in your binocular or spotting scope is called the “close” or “near” focus
95'
Height:
13"
Armored:
A binocular or spotting scope whose body is clad in rubber or polyurethane armor is said to be armored. Armor can be applied for looks, a better grip, noise-proofing, etc. An armored body does not guarantee that a binocular or spotting scope is waterproof, although most waterproof optics are armored.
Partial
Waterproof:
No
Weight:
The weight of this product.
72.8 oz.
Warranty:
1 year
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  • Padded nylon carrying/storage case
  • Protective snap-in lens caps
  • Eyepiece raingaurd
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Meade - 20 x 80mm Astro binocular

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Meade - 20 x 80mm Astro binocular
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Our Product #: M2080
Manufacturer Product #: B122080
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Meade’s 20 x 80mm Astro binocular is an optically good performer for astronomical observing at a reasonable price . . .





. . . our 34th year