Nikon Action Extreme ATB 10X50 Binocular 7245 Binoculars
From the Manufacturer
The Monarch ATB 42mm with Dielectric High-Reflective Multilayer Prism Coating binocular features brighter, sharper colors, crisp and drastically improved low-light performance. A new body style provides unparalleled strength and ruggedness in a package that is comfortable to carry all day. With rugged rubber armor for added durability and a firm grip even in the worst conditions, Nikon guarantees every ATB to be 100% waterproof and fogproof, each is backed by Nikon's 25 Year Limited Warranty and No-Fault Repair/Replacement Policy. The new Monarch ATB 42mm with Dielectric High-Reflective Multilayer Prism Coating binocular is available in 8x42, 10x42 and 12x42. It is also available in Team REALTREE models with the REALTREE APG HD camouflage pattern. Technical Specs
Additional Action EX Highlights: Warranty Information
|Magnification x |
|Objective Diameter ||35 |
|Angular FOV – Real ||9.3 |
|Angular FOV – Apparent ||59.3 |
|FOV @ 1000 yds ||488 |
|Close Focus Distance (ft.) |
|Exit Pupil (mm) |
|Relative Brightness ||25 |
|Eye Relief (mm) |
|Size (L&W) (in) |
|4.7 x 7.2 |
|5.4 x 7.4 |
|7 x 7.7 |
|7 x 7.7 |
|7 x 7.7 ||7 x 7.7 |
|Weight (oz) |
Nikon is dedicated to quality, performance and total customer satisfaction. If your Nikon binocular, Spotting Scope or Fieldscope requires service or repair not covered by our 25 Year Limited Warranty, Nikon will repair or replace it (even it was your fault) for just $10, plus return shipping and handling.
Excludes – StabilEyes, Laser Rangefinders and Spotting Scope/Fieldscope eyepieces. FAQ's Real field of view
Real field of view is the angle of the visible field, seen without moving the binoculars, measured from the central point of the objective lens. The larger the value is, the wider the viewfield available. For example, binoculars with a wider field of view are advantageous for locating fast-moving wild birds within the viewfield. This also applies for finding small nebulas or a cluster of stars in astronomical observations.
Apparent field of view
Apparent field of view is the angle of the magnified field when you look through binoculars.
The larger the apparent field of view is, the wider the field of view you can see even at high magnifications.
With the conventional method used previously, the apparent field of view was calculated by multiplying the real field of view by the binocular magnification. (With this formula, apparent field of view wider than 65˚ is called wide field of view.)
After revision, Nikon's figures are now based on the ISO 14132-1:2002 standard, and obtained by the following formula: tan ω' = τ x tan ω Apparent field of view: 2ω' Real field of view: 2ω Magnification: τ
(With this formula, apparent field of view wider than 60° is called wide field of view.)
For example, the apparent field of view of 8x binoculars with an 7.0°real field of view is as follows: 2ω' = 2 x tan-1 (r x tan ω)
= 2 x tan-1 (8 x tan 3.5) Relative Brightness
Relative brightness value is obtained by squaring the diameter of the exit pupil. The greater the relative brightness is, the brighter the image will be. With 8x42 binoculars, the brightness is (42÷8)2= 28.1. This means that if the magnification is the same, the larger the effective diameter of the objective lens, the brighter the image will be.
Do binoculars with the same exit pupil offer the same brightness?
No. Brightness may vary even if the exit pupil is the same. This is because the amount of light reaching the viewer's eyes varies according to the number of lens elements and quality of lens/prism coatings. Superior optical design and highquality coating greatly contribute to the brightness of binoculars. Brightness values specified in product brochures, etc. are theoretical ones calculated in the design process. Please note these factors when comparing actual brightness values. Prisms
Prisms are what let you see a correctly oriented image when you look through a pair of binoculars. There are two types of prisms in common use, Porro prisms and roof prisms.
Roof prisms are essentially in line inside the optical tubes, and make for a more compact set of binoculars. Roof prism binoculars have straight tubes (the front/objective lens is in line with the rear/ocular lens), and are therefore more compact, an important consideration for the sportsman. They usually have two pivot points between the tubes, and are more difficult to adjust to the spacing of your eyes. Roof prisms can give an optical image equal to the best Porro prisms, but for technical reasons they usually do not. To be really good, roof prism binoculars have to be in the high price class. Do not attempt to economize on roof prism binoculars.
Porro prism binoculars can be identified by their offset tubes; the objective lens is not in line with the ocular lens. The front lenses are usually closer together than the rear lenses, but the reverse can also be true, particularly in compact models. The Porro prism design is usually optically superior to the roof prism design, especially in medium priced class binoculars. Porro prism binoculars have a single pivot between the two halves of the binocular, and are therefore easy to adjust for the distance between your eyes.
Like roof prisms, not all Porro prisms are created equal. BAK-4
prisms are the best; they are made of superior optical glass that produces clearer images. These are what you want in your binoculars. BK-7 prisms are also used, usually in lower priced binoculars. These are satisfactory, but they are inferior to the BAK-4 prisms. Some manufacturers will not tell you what kind of prisms they use, usually because they are of inferior quality. BAK-4 prisms show a truer round, which translates to better light transmission and edge-to-edge sharpness Prism Coatings
Multilayer coating is also applied to prisms to raise transmittance. A roof prism system has one surface that does not feature total internal reflection, so vapor deposition with metals, etc. must be used to raise the reflectivity of this surface. Also, phase-correction coating on roof surface ensures high-contrast images. *Binoculars' brightness and contrast are affected by not only prism coatings, but also the number of objective lens and eyepiece lens, and types of coatings.
|Metal-vaporized, high-reflectivity prism coating |
Using vacuum-vaporization technology, metallic material such as aluminum or silver is applied to the reverse side of a prism surface that is not totally reflective. This raises the reflectivity of the prism mirror surface.
Dielectric high-reflective multilayer prism coating
This coating features reflectance that exceeds 99%. By utilizing light interference, this coating assures high reflectivity across the full visible range, and ensures high color reproducibility.
|Reflectance characteristics of prism coatings on mirror surface |
The horizontal axis indicates the wavelength of light. The vertical axis indicates the reflectance of light.
Binoculars' brightness is determined not only by the reflective mirror, but also by the total optical system such as the number of lenses and quality of coatings.
A roof (Dach) surface can cause phase shift of light that affects image resolution. This phenomenon is caused by phase differences arising from total light reflection on a roof (Dach) surface and it can occur with even a perfectly processed prism. Phase-correction coating is applied to the surface to minimize loss of resolution, ensuring high-contrast images. Twilight Factor
The factor that has the greatest impact on resolution or image detail, will be dependent upon the amount of light available during the time of observation. During daylight hours, when your eye pupil size will be only about 2 to 3mm, magnification will be the principal factor in image resolution. At night, with the eye pupil dilated to 6 to 8mm, aperture size is the controlling factor. In twilight conditions both of these factors control resolution effectiveness and the twilight factor is the term that compares binocular performance under these conditions.
The twilight factor is calculated by taking the square root of the product of the magnification and the aperture. The higher the twilight factor, the better the resolution of the binocular when observing under dim light conditions. For example, a 10 X 40 (twilight factor 20) would effectively resolve better under these conditions than a 7 X 35 (twilight factor 15.4) even though the 10 X 40 has a smaller exit pupil. Remember, however, that the twilight factor does not take into account the transmittance or quality of the optical system.