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Photoshop Becker binoculars buying guide

Despite their popularity, how binoculars work, what makes one better (or different) than the other, and what all the numbers mean, is still quite a mystery to many interested parties. Read on to find out everything you need to know about the ubiquitous binoculars before making your choice so you can be sure you are choosing the right binoculars for what you are looking to observe.

The basics

Put simply, binoculars use a series of lenses, elements, and prisms to create a magnified view of distant people, places, or things. Using two parallel optical tubes allows you to observe with both eyes, which is more convenient and natural than using a spotting scope or telescope, which requires you to keep one eye closed. It also maintains depth of field with your eyes open, giving you a rich and immersive experience that gives the scene a more lifelike 3-D appearance.

When you buy binoculars, you will find that some look very slim and some look rather chunky. This is because the look and size of binoculars is determined by the type of prism used. Prisms are used to correct the horizontal and vertical alignment of the gaze so that the scene looks natural; without a prism, the binoculars would turn things upside down and slip. There are two main types of prisms: roof prisms and Porro prisms. The glass elements in a roof prism are lined up with each other, making roof prism binoculars more streamlined and easier to hold. In Porro prisms, the glass elements are offset from one another and, compared to similar roof prism models, can offer a greater depth of field and a wider field of view. This is achieved by folding the light path, which shortens the length and spreads the lenses further apart.

There can be a wide price range between what appear to be similar binoculars. For example, Photoshop Becker sells binoculars that cost between less than 80 euros and almost 2,000 euros. The main reasons for such a wide price range are the quality of the optics, the type of coatings that are applied to the lenses, and other features that can be added, such as the housing material. In addition, the type of prism can (and often is) a factor in determining the price. Due to the physical conditions in the design and manufacture of the compact roof prism form factor, you can own a roof and a Porro binoculars that appear identical in terms of quality and performance, but the price of the roof prism version is higher than that of the Porro binoculars. The good news is that when form factor is not an issue, many people find that by choosing a Porro prism they can upgrade the quality of their binoculars without breaking their budget.

From a technical point of view, the type of prism used in binoculars is a double Porro prism, but it is always shortened to "Porro". It is also always capitalized because it is the last name of the inventor Ignazio Porro who designed this prism system around 1850. This most basic of all prism configurations is defined by the folded light path, which shifts the point at which light enters and exits the prism, giving the familiar look of "traditional" or "old-fashioned" binoculars.

The term "roof prism" was originally used for the Abbe-Koenig (AK) prism design, which corrects an image horizontally and vertically while maintaining a straight line from the point at which light enters and exits the prism. While the AK prism configuration is the most common, there are others that are variations of the original AK roof prism, such as the Amici and Schmidt-Pechan (SP). Although they serve the same basic function, the optical paths take different paths to correct the image orientation. The main advantage of the SP design is that it is more compact than the Amici and AK prisms, resulting in thinner optical tubes that are easier to hold, especially with long glazings. Zeiss is known for using SP prisms.

Pro tip: Since Porro prism binoculars are usually cheaper to manufacture than roof prisms, you can often get a higher quality and larger Porro model for about the same price as a comparable roof prism.

Binoculars Glossary: ​​What You Need To Know

Magnification and lens All binoculars are identified by a series of numbers, such as 10x42 and 7x20, which relate to their magnification and lens diameter, respectively. Using the example of 10x42, 10x means that the binoculars have a 10x magnification, so that the view through the binoculars appears ten times closer than with the naked eye. Binoculars with 7 to 10x magnification are sufficient for most situations. Theatergoers should choose something in the 3-5x range, depending on their seat; Sports fans will be happy with a 7x model, while remote viewing hunters will need 10x or higher. Keep in mind that for many users it can be difficult to keep binoculars larger than 10x42 stable for long periods of time, so a tripod should be considered when looking at models with higher magnifications or larger lenses.

The higher the magnification, the smaller the field of view

The "42" in our 10x42 binoculars refers to the diameter of the objective (front) lens in millimeters. Since the lenses often make up the majority of the optics, this affects the overall size and weight of the binoculars and how much light they can hold. Basically, larger lenses let more light through than smaller ones, which means that the images appear brighter, sharper and clearer. However, the larger lenses will also add bulk and weight, and this is where certain tradeoffs need to be considered in determining whether certain models are convenient to carry, store, hold, and use.

Zoom binoculars offer variable magnification and are displayed at 10-30x60. In this example, 10x magnification is at the bottom and 30x magnification is at the top. Most models have a thumb lever or wheel within easy reach so you can adjust the magnification without changing the handle or removing the eyepieces from your eyes. While zooms offer greater versatility, there may be a noticeable deterioration in image brightness and sharpness somewhere in the zoom range as the optical path and physics of the prisms have been optimized with a single effort and image quality could suffer as the magnification removed.

Exit pupilThe exit pupil is the size of the focused light that hits the eye. To see the exit pupil, hold the binoculars eight to ten centimeters from your face and note the small points of light in the center of the eyepieces. The diameter of the exit pupil, which should always be larger than the pupil of your eye, is directly influenced by the lens diameter and the magnification. The pupil of a human eye ranges from about 1.5 mm in bright conditions to about 8 mm in the dark. If the diameter of the exit pupil of your binoculars is smaller than the pupil of your eye, it will appear as if you are looking through a peephole. Keep in mind that the eyes become less dilated with age, so the exit pupil becomes more important as the user ages.

The diameter of the exit pupil of a binocular is determined by dividing the front lens by the magnification: a 10x42 binocular has an exit pupil diameter of 4.2 mm. This is a generous size and usually larger than the pupil of the eye. But 10x25 binoculars have an exit pupil of only 2.5 mm, which is smaller than the average pupil dilatation and more difficult to see through.

Zoom binoculars can have a perfectly acceptable exit pupil diameter at low magnification, but it is somewhat smaller at high magnification. For example, these 10-30x60 binoculars have 10x magnification in the lower area and 30x magnification in the upper area. At 10 times the diameter of the exit pupil is a remarkable 6 mm, at 30 times it is only 2 mm.

The exit pupil is ideally larger than the dilated pupil.

Pro tip: Hunters, ornithologists, and astronomers should keep the magnifications at 8x and below and increase the objectives to over 50mm to create wide exit pupils like this pair of 8x56 from Steiner. I used this particular pair in the middle of the night and they were able to completely cover my pupils which improved my eyesight despite the dark surroundings (you can read my review of them here if you want to know more). Boaters should also consider this type of configuration, as the wide exit pupil helps minimize the disorientation that often occurs when looking through binoculars when pounding or rolling water.

Eye reliefThe eye relief is the optimal distance from the eyepiece to the eye or the focal point at which the light passes through the eye lens (eyepiece). Manufacturers install eyecups on the eyepieces to bring the user's eyes into the correct distance from the eyepieces and to facilitate use. When you wear glasses, the lenses position the eyepieces beyond eye distance, which affects image quality and your ability to focus. Many binoculars offer diopter adjustments on one of the eyepieces so most users can adjust the focusing system on their eye receptors in order to use the binoculars without glasses. If you share the binoculars with other users, the eyecups are often adjustable. Simple eyecups can simply be folded back so that you can place your glasses closer to the eyepiece lens. Another type are adjustable eyecups that rotate in and out to precisely set the correct distance for the individual user.

In general, you will find that models with a longer eye relief have a smaller field of view than similarly priced models with a shorter eye relief. Achieving superlative specifications in both categories is an expensive optical engineering process. It's always good to have a wide field of vision. So decide how much eye relief you need and buy binoculars that offer the widest field of view. The field of view is discussed in more detail below.

Glass, prisms, and coating

GlassIt depends on the type and quality of the glass used for the lenses and prisms. If it's not properly sanded and polished, it can bend light strangely, causing colors to look distorted, not being sharp, or causing distortion around the edges. Special glass, such as glass with low or extra low scatter, is constructed in such a way that it has practically no distortion and allows light to pass through better without bending it. The resulting images are generally clearer, sharper, with true color reproduction and higher contrast.

You can also find some binoculars made with "eco-glass". This general term refers to environmentally friendly glass that does not use lead or arsenic. While this may or may not affect image quality, if your lenses break or you need to dispose of your binoculars, you can be assured that you are not adding to additional chemical pollution.

BAK4, BK7 and SK15 prisms The discussion in the introductory sections dealt with the two main types of prism configurations, but beyond that, the materials from which the prisms are made have a major impact on image quality. BAK4 or barium crown glass is considered to be the best type of prism material. It has a high index of refraction and a lower critical angle than other materials, which means it lets light through better and less light is lost through internal reflections - such as internal bubbles trapped during the manufacturing process.

BK7 glass is arguably the most commonly used material for binoculars. While it may be of a slightly lower quality than BAK4, it is still optical glass, which means it has excellent light transmission properties and a limited number of internal imperfections.

The easiest way to tell if your binoculars are using BAK4 or BK7 is to turn them around, hold them 6 to 8 inches away from you, look at the lens, and observe the exit pupil. If you can see an angled side to the general roundness of the image, the binoculars have BK7 prisms. BAK4 prisms have a rounder exit pupil, which leads to better light transmission and edge sharpness. SK15 glass is an atypical material that strikes a middle ground between the two above. It has a higher index of refraction than both, but has a dispersion (measured on the Abbe scale) that is between BAK4 and BK7. Images seen through SK15 prisms are very clear and rich in contrast.