• 18xMagnification: Magnification The magnification of a binocular refers to how many times larger an object appears. For example, with a 10x magnification an object 1000 yards away would appear to be only 100 yards away.
• 50 mmObject Lens Diameter: Objective Lens The objective lens is the larger of the outer lenses in your binoculars. These lenses are what gather all the light that you see; the bigger the lens the more light allowed in. A larger objective lens also tends to provide better resolution and more detail than a smaller one. The sizes range from a tiny 15mm for theater glasses to 50mm and larger for low-light and spotting binoculars.
  Tip: While larger lenses allow more light in, they also make the binoculars heavier. Consider how long you may be holding the binoculars, or if you will be using a tripod.
• 2.8 mmExit Pupil: Exit Pupil The size of the image as seen from the binocular's eyepiece. This is the circle of light seen in the eyepiece seen from about 10 inches away. Commonly used as a measurement of how bright the binoculars are. You can figure out the exit pupil diameter by dividing the objective lens diameter by the magnification power. 10x50mm binoculars would have a 5mm exit pupil.
  Tips: A binocular works best when the exit pupil diameter matches your eye's pupil diameter. A smaller diameter of around 2-3mm is good for binoculars for bright daytime use. Larger exit pupils of around 7mm are good for low light conditions and star gazing.
• 3.8°Angle of View: Angle of View The Angle of View is the angle between the left and right edges of the field of view from the binocular's point of view. This angle will generally get smaller with greater magnification.
  Tip: Binoculars vary, some will have a wider angle of view than others of the same magnification.
• 68.4°Apparent Angle of View: Apparent Angle of View The Apparent Angle of View is the angle of view with the binocular's magnification figured in. This is simply the angle of view multiplied by the magnification. For a 10x magnification and a 5° angle of view the Apparent would be 50°. This is directly related to the Field of View, but is often used to compare binoculars.
• 194 ft.Field of View(@1000yrds): Field of View Field of view is a measurement of the area visible at a given range. So with a pair of 8x binoculars you may be able to see an area 330 feet wide from a range of 1000 yards.
  Tip: Binoculars vary, some will have a wider field of view than others of the same magnification.
• 15 mmEye Relief: Eye Relief This is the distance that the binocular can be held from your eyes and still provide a good image. A longer eye relief is better for eyeglass wearers, as it will allow them to continue to wear their glasses while viewing.
  Tips: A longer eye relief is generally preferable, but a simple solution, though not always used, is having adjustable eye cups. These can usually make up for shorter eye relief, which is common in lower end binoculars.

• 7.8Brightness Index: Brightness Index This is the square of the exit pupil diameter. A 3mm exit pupil binocular would have a brightness index of 9. This is a common way to measure the brightness of a binocular.
• 19.7 ft.Minimum Focusing Distance: Minimum Focusing Distance This is the minimum distance that the binoculars can render a clear image.
  Tips: The short minimum focusing distance is nice when viewing nature, going to the museum, etc. It is not of paramount importance in buying binoculars but as with everything else, it depends on how you plan to use them.
• 7.5 in.Length: Length Length of the binoculars is measured from the objective lens to the eyepiece.
• 6 in.Width: Width Width of the binoculars is measured from the left side to the right side of the binocular at it's widest point.
• 3.3 in.Height: Height Height is measured from the bottom of the binoculars when laying down flat to the highest point on the top.
• 41.7 oz.Weight: Weight Weight is an important consideration when buying a new pair of binoculars. You should consider how long you will be holding them up to your eyes, and whether or not you intend on using a tripod. Larger objective lens binoculars will weigh more than smaller lenses. Also higher quality binoculars tend to weigh more due to higher grade materials used.
• 58-76 mm.Interpupillary Distance: Interpupillary Distance The distance between the centers of a person's pupils. Every binocular has a range of movement, by pulling the barrels inwards/outwards, to accommodate different IDs - e.g. "56-72mm" means the minimum ID is 56mm and the maximum ID is 72mm. If your ID is 54mm you will have difficulty seeing through such a binocular because the barrels will not line up with the centers of both your eyes.
  Tips: Most binoculars have an adequate interpupillary distance range for most people. However, if children will be using the binoculars often you may want a binocular with a minimum ID of around 56mm or below.

Canon 18x50 Image Stabilized All Weather Binoculars

• Image Stabilization System at the touch of a button
• High Magnification 18x Optics
• Large-diameter Objective Lenses
• Multi-Coated Ultra-Low Dispersion (UD) Objective Elements
• Doublet field-flattener for sharp, distortion-free images from edge-to-edge
• Good Eye Relief for eye-glass wearers
• Shock-and-Water-Resistant Construction
• Non-slip rubberized exterior

Image shake has always been a problem for people who use binoculars for long periods at a time. Even the steadiest hand shakes a little and that movement is magnified by the power of the binoculars until it can become unbearably distracting. For most binoculars the solution is a tripod; but this isn't always practical for fast moving sports events or for tracking birds or wildlife, or even looking out the window of a moving car. Canon's designers have solved this problem with the Variable Angle Prism (VAP) that instantly and precisely adjusts the visual path through the binoculars to maintain a perfectly steady image. The shake free performance not only enhances your ability to view fine detail but also reduces eyestrain and fatigue. To really understand the difference you must try them yourself but an easy comparison would be to imagine the ease of reading a book while being pulled down the road in a Radio Flyer Wagon and being driven around in the back of a Cadillac.

Even without the Image Stabilization these are excellent binoculars. The large diameter objective lenses provides a wide, extra bright field of view, the multi-coated Ultra-low Dispersion (UD) objective elements add contrast, clarity and color fidelity. A 15mm eye relief provides comfort for eyeglass wearers. The Shock-and-Water-Resistant Construction with non-slip rubberized coating enables use even in heavy rain.

• Power Source: Two size AA batteries (Optional Battery Pack BP-B1 can also be used)
• Image Stabilizer Continuous Operation Time: Approx. 2.5hours (At room temperature with alkaline batteries. Measured according to Canon's testing conditions.)
• Battery Check: indicator lamp provided.