Yukon 8x40 Futurus

Question : What do the numbers 10x25 / 10x50 / 7x50 / 20x60 / 20x80 / 8-20x50 / 10-30x50 next to the binoculars mean?

Answer: The first number in the notation 7x50 means the angular magnification (seven times), and the second - the diameter of the lenses expressed in millimeters. A record such as 8-20x50 or 10-30x50 means that we deal with a pair of binoculars with a zoom, ie equipped with a smooth magnification change system, here from 8 to 20 times or from 10 to 30 times. 50 of course means the diameter of the lenses.

Question : Is the set includes a case and a strap to hang the binoculars around the neck?

Answer: Yes, each pair of binoculars has a case and a neck strap, usually also caps for lenses and eyepieces, unless it is clearly stated that they do not.

Question : What is the influence of the magnification and the diameter of the objective lenses on the image of a pair of binoculars?

Answer: The greater the magnification , the greater the perceptibility of details, but also the less surface brightness of the objects. Therefore, if we are looking for hunting binoculars, the magnification should be between 7 and 10x, for birds and landscapes we recommend binoculars with a magnification of between 7 and 12x, and for observing airplanes, binoculars with high magnification of 15-20x are usually chosen or zoom binoculars.
In turn, the larger the lens diameter, the greater the resolution of the binoculars and the brighter the image, but also the greater the weight and size of the binoculars, sometimes requiring a photographic tripod.

Question : I still don't know which pair of binoculars to decide on, I want to buy a universal pair of binoculars with good parameters, so that "you can see a lot". Which one to choose?

Answer: The most universal parameters of the binoculars are 10x50 and we recommend them like that - they are distinguished by good visibility and brightness at the same time, with a large field of view and they do not require a tripod.

Question : Is it better to choose a pair of binoculars with a constant magnification or a pair of zoom binoculars?

Answer: The zoom binoculars have an additional optical system that allows you to change the magnification. In optics, often "less is more". Each additional optical system, which is not a corrector of one of the optical defects, always has a negative impact on the image quality. It's like with photographic lenses - the most valued are those with a fixed focal length, not those with a variable focal length. On the other hand, the zoom binoculars are more versatile, because nobody carries 2-3 binoculars with different magnification.

Question : Do these binoculars have glass lenses or maybe plastic ones?

Answer: All decent binoculars have complete glass optics, as only glass can be ground and polished to shape, while polymers ("plastics") have a limited accuracy of forms .

Question : You write in the specification about anti-reflection / anti-reflection layers, what is it? Are the anti-reflective layers so that I cannot be seen, that is, so that the binoculars do not give "reflections", eg from the Sun?

Answer: Anti-reflective layers, also known as anti-reflection layers, are used to increase the efficiency of an optical system, for example binoculars, but basically any other device. The optical efficiency determines how many percent of the beam entering the optical system passes through the system. It must be known that when the light falls on the border of two optical centers, eg glass / air, a certain fraction of the beam is reflected. We know from our daily experiences that you can see through the glass - precisely for this reason. To minimize losses, anti-reflective layers are used, thanks to which more light crosses the border of the centers and less is reflected.
Anti-reflective layers can be of different types and classes, often they constitute the price of the best binoculars, the total efficiency of which can reach even 95%.
It is worth knowing that anti-reflective layers are applied to the optical surfaces of microscopic elements, telescopes, observation spotting scopes, sights, photographic lenses or night vision devices for the same purpose as in the case of binoculars.

Question : When you describe the binoculars you write about the prism glass, BK7 and BaK-4, what is it about?

Answer: Most of the optical prisms are made of BK-7 (borosilicate) or BaK-4 (barium glass) glass. BAK-4 is a higher quality glass and produces brighter and sharper images. It is also more expensive glass, usually used in high-end binoculars. It is worth paying attention to this, especially if you are looking for binoculars for hunting and astronomical applications.

Question : In the description I did not find some parameters of the binoculars that I found on other pages. Can I find out what brightness these binoculars have and what is twilight efficiency?

Answer: For the sake of clarity of description, we usually do not give secondary parameters that do not provide any additional information than those provided. Nevertheless, you can calculate these parameters yourself:
• the exit pupil is the area in the eyepiece where the image is formed; The exit pupil diameter is equal to the ratio of the lens diameter through the magnification, e.g. for 7x50 binoculars it is 50/7 = 7mm, for 10x50 binoculars: 50/10 = 5mm, and for 20x60 binoculars: 60/20 = 3mm; this parameter is usually given in the description

• relative brightness is the square of the exit pupil (exit pupil: see above); for 10x50 binoculars the output pupil is 5, i.e. the brightness is 25, similarly for 7x50 binoculars the brightness is 50, for 20x60 binoculars the brightness is 9 etc.

• twilight factor is another secondary parameter that night hunters like to pay attention to; it is equal to the square root of the product of magnification and the diameter of the lenses; having an ordinary calculator, we can quickly calculate this parameter:
- for 8x40 binoculars: 17.9
- for 7x50 binoculars: 18.7
- for 10x50 binoculars: 22.4
- for 20x60 binoculars: 24.5

Question : I am looking for binoculars for astronomy, how should I choose?

Answer: This question cannot be answered simply and briefly. Astronomical binoculars are simply very good binoculars. This means a very good correction of optical aberrations (mainly chromatic aberration and distortion at the edges) and high optical efficiency. For these reasons, we do not recommend zoom binoculars for astronomy, maybe with a few exceptions. Astronomical binoculars do not have to have a high magnification - this is what a telescope is for in order to conduct observations at high magnifications. Binoculars - usually - should be handy, so you can always take them with you when you can't take your telescope with you - then you choose 7x50, 10x50 or 15x70 binoculars. Usually, large binoculars dedicated to astronomy, type 20x80, 22x100, constitute a separate class of optical instruments that require observation from a tripod.
For a beginner observer, astronomical binoculars are used to discover the sky, the colors of stars, and to find the brightest objects in the deep sky. For an advanced observer, large binoculars are a very efficient device for the observation of comets, variable stars, nebulae, star clusters and galaxies.

Question : I am looking for binoculars for a yacht / canoeing / fishing / sea trip, what should I choose?

Answer: Water binoculars must be waterproof, nitrogen-filled and have a magnification of 7x, as only this magnification can guarantee a bright and stable image.

Question : I am looking for bird watching binoculars, should I get high magnification binoculars (16x, 20x or zoom binoculars)?

Answer: For bird observation we usually recommend binoculars with small or medium constant magnification, ie from 7 to 12 times. The optimal set for the bird watcher is a pair of binoculars with a fixed magnification and an observation telescope with zoom on a photographic tripod.