Weatherproofing: There are two types of designations commonly used when talking about weatherproofing. The differences are: a weather-resistant optic will withstand the occasional light shower but will not withstand submersion or extended use in wet conditions. weatherproof or waterproof optics means that the optics shouldn't allow water intrusion under most circumstances. Sometimes they are even rated to a depth of submersion for a period of time. Some manufacturers will even have an IP (International Protection) Rating. Binoculars with external focusing are sealed with an "o" ring, and over time these can wear, dry out, or get damaged. The result is that moisture or dust can get into the interior, settle on the optics, and degrade your view. W12 × 19 designates a wide flange beam with a depth of 12 inches and a nominal weight of 19 pounds per foot.

When choosing a pair of binoculars, you are faced with making compromises. Binoculars that you use for astronomy will not be compact, and you probably won't take them hiking. Below are some things to consider based on use: Hiking/TravelThat first number that generally follows the model name of a pair of binoculars refers to the magnification. For example, an 8x42 pair of bins provide eight times magnification, which makes things look eight times larger. A 10x42 pair offers 10 times magnification, and so on.

Angie is a wildlife biologist that specializes in birds and avian research. She has worked for over 10 years on many different research, monitoring, and rehabilitation projects. She's seen birds in all sorts of places, including Northern Minnesota, coastal California, the Sierra's of California, Glacier National Park, Missouri, Arizona, and Kauai. She's currently a graduate student at UC-Davis working on a project with an endangered bird called the Ridgeway rail in the San Francisco Bay area. What type of binoculars do you consider ideal and use, and for which situations? Binoculars are optimized for different uses. This guide will help you understand these instruments a little better so that you can make an informed decision when choosing a pair for yourself. Refer to our best binoculars review to see which we like best and why. Step 1: What Size do You Need W-beams - wide flange beams - are stout, sturdy beams with wide flanges positioned perpendicularly to the web of the material giving them their characteristic shape and distinguishing them from I-beams.Merle, Renae. "GAO Questions Cost of Joint Strike Fighter." Washington Post, 16 March 2005. Retrieved: 9 January 2010. The Joint Strike Fighter evolved out of several requirements for a common fighter to replace existing types. The actual JSF development contract was signed on 16 November 1996. The JSF program was created to replace various aircraft while keeping development, production, and operating costs down. This was pursued by building three variants of one aircraft, with the initial goal of the variants sharing over 70% of their parts. [2] Long multiplication with decimals using the standard algorithm has a few simple additional rules to follow.

Deflection and stress, moment of inertia, section modulus and technical information of beams and columns. Long multiplication means you're doing multiplication by hand. The traditional method, or Standard Algorithm, involves multiplying numbers and lining up results according to place value. These are the steps to do long multiplication by hand: If you're looking for something with greater than 12x magnification, binoculars may not be for you. Above that mark, hand shake becomes unwieldy, even for the steadiest hands in the west. At that point, you'll be looking at a tripod-mounted spotting scope instead. There are a number of differences between the X-35 and F-35, which was designed to be an operational weapon system. The forward fuselage was lengthened by 5 inches (13cm) to make room for mission avionics, while the horizontal stabilizers were correspondingly moved 2 inches (5.1cm) aft to retain balance and control. The diverterless supersonic inlet cowl shape changed from a four-sided to a three-sided shape and was moved 30 inches (76cm) aft. To accommodate weapons bays, the fuselage section was fuller with the top surface raised by 1 inch (2.5cm) along the centerline. Following the designation of the X-35 prototypes, the three variants were designated F-35A (CTOL), F-35B (STOVL), and F-35C (CV). [27] The X-35B on display at the Steven F. Udvar-Hazy Center. Aircraft on display [ edit ] The X-35C on display at the Patuxent River Naval Air Museum. Use long addition to add your number columns from right to left, carrying as you normally do for long addition.When you've multiplied the ones digit by every digit in the top number, move to the tens digit in the bottom number. The first is the F-35A, a conventional takeoff and landing (CTOL) variant. It is the smallest and lightest version, and is intended primarily to replace the U.S. Air Force's aging F-16 Fighting Falcons and A-10 Thunderbolt IIs. This is the only version with an internal gun, the GAU-22. The F-35B is the short-takeoff and vertical-landing (STOVL) variant due to replace the U.S. Marine Corps AV-8 Harrier IIs and F/A-18 Hornets, and Royal Air Force/ Royal Navy Harrier GR7/GR9s beginning in 2015. The second number in the bin world represents the lens diameter of the outer lens; this represents the amount of light let in for a clearer, sharper image. This becomes important at dawn and dusk. If you are just shopping for the best deal and want an inexpensive product, ensure that the second number represents at least five times the magnification: so "40" is most frequently associated with 8x , and "50" is most frequently associated with 10x. This does not mean the second number needs to be even or odd, so go for the "8x43" or "10x54" if you like. What is the most important aspect that you wouldn't compromise when buying a pair of binoculars? Armor is an outer coating of rubber or synthetic material. This protects the binoculars from scratches and corrosion. It can also make the binoculars easier to hold. A rubber coating does not make a pair of binoculars waterproof.

Area Moment of Inertia, Moment of Inertia for an Area or Second Moment of Area for typical cross section profiles. When out on the water, a rugged, waterproof design is essential. Low magnification will make it easier to see on a pitching boat. A magnification of 7x to 8x should do just fine. You will also want a larger objective lens. Look for an objective lens that is equal to or greater than 35mm. Suggested size: 7X50. Astronomy You've probably noticed that most binoculars are described by two numbers separated by an x, 8x42, for example. That first number is the magnification (more on that in a second), and the second number is the size (in millimeters) of the objective (front) lens. The size of the objective lens largely determines the overall size of the binoculars, so that second number essentially describes their size. In broad daylight, the average adult has a dilated pupil of 3mm. The diameter of a healthy young adult can range be between 2mm to 8mm, and as you get older, it can get reduced to 5-6mm. A smaller exit pupil also makes it harder to center your eye on the image. Your eye needs to be centered exactly over the exit pupil to see.Field of View/Angle of View is the diameter of the circular viewing field. It is defined by the width in feet or meters of the area visible at a distance in yards or meters (usually 1000 yards in the USA). The angle of view is the maximum view you are capable of seeing through the binoculars expressed in degrees. You can easily convert from one measurement to the other by knowing that one angular degree is equivalent to 52.5 feet at 1000 yards. Multiply 52.5 by the angle of view to find the linear field of view. Or divide the linear field of view to get the angle of view. steel wide flange beams. Wide flange beams are designated by the letter W followed by the nominal depth in inches and the weight in pounds per foot. Thus The next major advancement was Keplerian Optics which used a convex eyepiece and relay lens in between the objective lens and eyepiece to flip the image. The lengths of these binoculars and telescopes were quite large to account for the long focal length. The larger the objective lens, the more light that can get into the binoculars, and thus the brighter the image. Larger objective lenses also make the binoculars themselves larger and heavier. You'll want to find a balance between brightness and portability that works for you. Eden, Paul, ed. (2004). The Encyclopedia of Modern Military Aircraft. London, UK: Amber Books. ISBN 1-904687-84-9.