8x25mm Nature DX compact roof prism

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The Celestron 8x25mm Nature DX is a very compact and light (only 12.1 ounces) roof prism binocular with good performance at a very reasonable price. It is fully multicoated for bright images, with phase-corrected BaK-4 prisms for increased sharpness, armor, nitrogen-purged waterproofing, and more. The Celestron 8x25mm Nature DX is the perfect size to tuck into a suicase or car glove compartment for a vacation trip, as well as slip into a coat pocket for neighborhood and backyard birding, hiking, and camping. The Celestron 8x25mm Nature DX is compact and light enough to take with you anywhere and anytime you need a good binocular, but a compact size and affordable price are mandatory. 

Image quality is good, with very minor field curvature (the image stays essentially in focus all the way across the field). Geometric distortion (pincushioning) is almost non-existent. Chromatic aberration is present, but barely noticeable while observing. Colors are natural and true to life, although not blindingly bright in low light due to the small 25mm aperture. By any standard you might care to choose – performance, features, build quality, feel in the hand and ease of carrying, value for money – this Celestron 8x25mm Nature DX roof prism is a good choice for anyone who is looking for a good quality compact roof prism binocular at a budget price.

Features of this binocular . . .
  • Roof prism optics. Compact H-body roof prism using quality BaK-4 prisms. Internal center focus.
  • Fully multicoated optics. The optics are treated with multiple-layer antireflection coatings on all air-to-glass surfaces for good light transmission and high contrast.
  • Phase-coated prisms. The image-erecting roof prisms are made of high quality BaK-4 glass, multicoated to provide the brightest possible images. The prism faces have special phase-correcting coatings for peak contrast, color fidelity, and resolution. The resulting improvement is easily seen when looking for color and detail in the shadowed areas of a silhouetted or backlit bird.
  • Waterproof and fogproof. O-ring sealed and nitrogen-purged to be fully waterproof and fogproof in summer showers and monsoon rains alike.
  • Full armor. Forest green rubber armor on the rugged and lightweight polycarbonate body absorbs noise and shock and provides a good grip when wet.
  • Twist-up eyecups. The rubber-rimmed eyecups twist up for use without glasses and twist back down for eyeglass or sunglass use.
  • Eye relief. Eye relief is specified at 14mm, although will typically measure a mm or two less due to the eyepieces being recessed to keep them from getting scratched in use. There will be some vignetting for eyeglass wearers.
  • Good field of view. The field of view is a good 7.2° across (378’ at 1000 yards).
  • Good close focusing. Focuses down to 6.5’. This close focus combines with its wide 7.2° field to make it very usable for close-in birding and butterfly watching.
  • Fast focusing. Very fast focusing, as it takes little more than three-quarters of a turn of the ribbed focus knob to move from the 6.5’ close focus out to the horizon and beyond.
  • Rotary diopter correction. A variable diopter ring on the right eyepiece allows you to match the binocular optics precisely to your individual eyesight for a sharp image.
  • Standard accessories. An eyepiece rainguard, objective lens covers, a medium width (15/16” wide) cloth neckstrap, and a soft padded nylon carrying case with a belt loop.
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.
7.2°
Field of view 1000 yards:
378'
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.
3.13mm
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.
9.80
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.
14.14
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.

14mm
Interpupillary Distance:
56-72mm
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
6.5'
Height:
4.3"
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.
Yes
Waterproof:
Yes
Weight:
The weight of this product.
12.1 oz.
Warranty:
Limited Lifetime
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  • Soft case
  • Woven neck strap
  • Objective lens covers
  • Eyepiece rainguard
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8x25mm Nature DX compact roof prism

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8x25mm Nature DX compact roof prism
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Our Product #: C825ND
Manufacturer Product #: 71328
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If you need a good quality compact binocular at a sensible price, this very affordable Celestron 8x25mm Nature DX roof prism may be just the one you are looking for.





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