10 X 25mm UpClose G2 roof prism

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The surprising thing about this compact high power second generation Celestron UpClose G2 10 x 25mm roof prism is not the price. It’s how much you get for how little you spend. Respectable optics, armor, fully coated, water resistant, weighs only 11 ounces, and folds down to a very compact size that’s easy to fit in pocket, purse, or car glove compartment.

This Celestron UpClose G2 10 x 25mm is a neat little second or third binocular for traveling or vacations, and makes a very affordable binocular to start a youngster on a lifetime birding or nature study hobby. It costs so little that you won’t cry if the youngster uses it to drive tent pegs while on vacation or drops it in the lake.

Its BK-7 roof prism optics are fully antireflection coated for good light transmission and contrast. While the eye relief of 11mm is fine for optically unaided observing, it will somewhat vignette the field for those who must wear eyeglasses while birding.

Overall, this is a quite decent and very compact high power binocular at an extraordinarily low price. Its optics are more than acceptable, although they won’t stun you with their brightness due to the high magnification and rather small 25mm objective lenses. This is a daytime binocular, not one for late twilight or evening observing. It does not perform up to the standards of a Leica or Zeiss compact, but then again it is not priced like one, either. But as we said at the start, for the price, the performance of this Celestron UpClose G2 10 x 25mm roof prism just might surprise you.

Features of this binocular . . .

  • Roof prism design. The compact dual hinge roof prism design lets you fold this Celestron down to little more than the size of a pack of king-size cigarettes so it is easy to store in pocket or car glove compartment.
  • Fully coated optics. Antireflection coatings on all air to glass surfaces for high light transmission, including multicoatings on some surfaces.
  • Water resistant. While not nitrogen-filled and O-ring sealed to be fully waterproof, this Celestron roof prism will handle most showers and light rain without leaking.
  • Armor. Ribbed black rubber armor absorbs noise and shock. It provides a firm grip in spring and fall’s notoriously wet conditions. It also provides a more comfortable grip in the temperature extremes of broiling hot summer and icy cold winter.
  • Center focus. About one and three-quarters of a turn of the centrally-located focusing knob moves smoothly from one end of the focusing range to the other.
  • Diopter correction. A diopter ring on the right eyepiece allows you to match the binocular optics precisely to your individual eyesight for a sharp image.
  • Accessories. Comes with a thin corded neck strap and soft nylon carry/storage case.
  • 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).
    Roof Prism
    Field of view:
    The field of view (FOV) is the amount of observable world one can see at any given moment.
    Field of view 1000 yards:
    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.
    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.
    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.
    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.

    Interpupillary Distance:
    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
    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.
    The weight of this product.
    11 oz.
    Limited Lifetime
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    10 X 25mm UpClose G2 roof prism

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    10 X 25mm UpClose G2 roof prism
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    Our Product #: UC1025
    Manufacturer Product #: 71232
    Price: $19.95  Ground shipping for this item is $8.95 - Click for more info
    By adding 1 of these items to your cart your order total will be less than $100, and will ship within the 48 contiguous United States for $8.95. Add $80.05 to your order, however, and you qualify for free ground shipping (heavy items with fixed shipping, such as counterweights, excluded).
    MSRP: $21.05

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    Clear skies,

    Think you have to spend a bunch to get a decent high power compact roof prism? Think again. The Celestron 10 x 25mm UpClose G2 costs a lot less than a bunch . . .

    . . . our 38th year