How to Choose a Starter Birding Binoculars?

For bird watchers, a pair of binoculars is a must, it can not only help us observe more details of birds, but also bring beautiful enjoyment and delight our minds! The size and weight of the binoculars are moderate, suitable for carrying at any time, comfortable for observation, large field of view, very suitable for observing forest birds (the forest birds are not far from the observer and move at a fast angular speed), and the operation is also very simple! The requirements for birding binoculars are as follows:

  • Multiples: 7-10 times are more appropriate. Novices often like to use high magnification, but the image jitter brought by high magnification will offset the detail recognition under high magnification. In addition, high magnification must be matched with a large aperture objective lens to obtain good observation results, but large aperture will directly increase the size and weight of the telescope, affecting portability. sex. So the multiple is not the higher the better, for the average person, 7-8 times is enough!
  • Aperture: Aperture refers to the diameter of the objective lens, generally between 20-50 mm. Small aperture means small size, light weight, good portability, but low imaging brightness and poor observation comfort. The larger the aperture, the larger the volume and the heavy weight, the poor portability, but the high imaging brightness and the comfortable observation. The common 20 and 25 mm diameters mainly highlight portability and are suitable for backup mirrors. The 30mm and 32mm apertures are a compromise between effect and portability. The 42mm and 50mm apertures mainly highlight the observation effect and are suitable for the main mirror!
  • Exit pupil diameter and specifications: The exit pupil diameter is closely related to imaging brightness and viewing comfort. The calculation method of the exit pupil diameter is to use the objective lens diameter ÷ multiples. The exit pupil diameter of 2.5mm is suitable for bird watching in brightly lit environments, such as 8X20/10X25. The advantage of these specifications is that they are small in size and light in weight and easy to carry, but the viewing comfort is poor. The exit pupil diameter of about 4 mm can relax the requirements for light, such as 8X30/8X32/10X42, which can meet the bird watching requirements in most occasions. The exit pupil diameter of more than 5 mm is basically an all-weather type, especially suitable for observing birds at dusk and dawn, such as 8X42/10X50, with high brightness, clarity and comfort.
  • Prism: A prism must be added to the binoculars to obtain an erect image. Common prisms are divided into roof prisms and porro Generally speaking, the binocular lens with roof prism is more suitable for bird watching. Its appearance is that the lens barrel is two straight tubes, and the distance between the centers of the objective lens is small, which is suitable for observing close-range targets. It is also easy to be made into a nitrogen-filled waterproof structure, which is more suitable for harsh outdoor environments. Small size, light weight, good portability! However, the use of roof prisms requires the use of high-precision prisms and complex coatings to obtain excellent observation results, and the high cost leads to high prices. The binoculars using porroprisms are curved in shape, with a large distance between the centers of the objective lenses, and the nearest observation distance is long. It is not easy to achieve a nitrogen-filled waterproof structure (the left and right independent focusing can achieve high sealing, but this focusing method is not suitable for bird watching), and it is bulky and heavy. However, the advantage is that the optical technology is low, and good results can be obtained at a relatively low price. There is also a type of binoculars using an anti-porro prism, which is relatively light, but has a small aperture and is not suitable for the main mirror.
  • Closest viewing distance: Bird watchers usually wish to have a smaller closest viewing distance in order to observe birds hidden in bushes or grass. The closest observation distance of binoculars using roof prisms can be made relatively small, usually as close as 2.5 meters (for example, the closest observation distance of Tontube high-end 8X32 can reach 2.5 meters or less), the closest observation distance of binoculars using reverse porroprism The distance can even be less than 1 meter (such as Tontube's YBSP05, the closest focus can reach 0.5 meters)
  • Focusing type: When observing forest birds, the distance between the bird and the person is fluctuating. Only with central focusing can it adapt to the rapid changes in the distance of the observed object. Some central focusing porroprism binoculars (such as Swarovski's HABICHT 8X30 binoculars), in order to achieve a waterproof structure, the movable eyepiece is sealed with an O-ring, resulting in a large focus adjustment damping, and prolonged operation will cause fingers sore. As for the left and right focusing porro prism binoculars (such as military telescopes), the focusing speed is very slow, not suitable for observing fast-moving birds

7) Waterproof and shockproof: Bird watching activities are often carried out outdoors, and the observation environment is changeable. It is best to choose water-proof binoculars, so as to keep the inside of the mirror sealed and dry, without fog and mildew, and improve the use of the telescope. life. For the binoculars with rubber surface, not only the anti-shock effect is good, the optical axis is stable, and it is more comfortable to hold.

8) Coating: For porro prisms, only anti-reflection coating is enough. For roof prisms, reflective coatings are necessary. To obtain good results, in addition to anti-reflection coatings, phase coatings are also required. Therefore, when choosing a telescope, it is necessary to understand the various coating conditions of the telescope.

Anti-reflection coating: When light passes through the contact surface of glass and air, it will reflect, which will not only reduce the brightness of the image, but also reduce the contrast of the image and reduce the clarity of the image. Therefore, it is necessary to coat the contact surface with an anti-reflection coating to reduce reflection. Sometimes the factory will omit the coating on the inner surface in order to save costs, or use a simple single-layer film. The use of multi-layer film will significantly reduce the reflection of light. The multi-layer film of domestic telescopes often presents a dark green reflection. A good telescope should be coated with multi-layer films on all necessary surfaces. This telescope will be marked with FMC coating, but based on the current domestic commercial reputation, even if it is marked with FMC coating, it is not necessarily true.

Phase coating: The roof prism will divide the light in the optical path into two beams. When they meet, the opposite phases will interfere, resulting in blurred imaging. ). The use of this coating can improve the clarity of the image. Such as Tontube roof ridge binoculars YBRED02 YBRED07 and so on.

Reflective film: There is one surface of the roof prism that cannot fully reflect light. It must be coated with a reflective film to reflect light. The conventional treatment method is aluminized film. The advantage is that it is not easy to be oxidized, but the reflectivity is low. Silver plating has the advantage that the reflectivity is higher than that of aluminum film, but there is a risk of being oxidized, and the image is still yellowish. At present, the best method is to coat a dielectric film, which has good stability, high reflectivity, and small fluctuations with wavelength, so the image is bright without color cast.

9) Eye mask and exit pupil distance: For birders with myopia/aging eyes/astigmatism, bird watching is different from watching the scenery on the balcony. When watching the scenery from the balcony, you can take off the glasses and slowly adjust the focus, while bird watching is often worn first. After the glasses search for the bird, use the binoculars to observe directly. Therefore, a foldable or swivel-up soft eyecup is required, otherwise the complete field of view cannot be observed. A very hard eye mask can be very uncomfortable. In addition, the exit pupil distance should not be too short. An exit pupil distance of less than 15 mm will force the observer to put his eyes closely behind the eyepiece, otherwise the full field of view will not be seen. 

Although binoculars have many advantages, if you want to observe more details or observe waterfowl, you need a high-powered monocular birdwatching scope. In the next issue, we will talk about the requirements for monocular bird watching glasses.

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