Celestron 12x25 UpClose binocular Celestron binoculars opinie

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

Answer: The first number in the notation 7x50 means the angular magnification (seven times), and the second - the diameter of the objectives expressed in millimeters. A notation such as 8-20x50 or 10-30x50 means that we are dealing with zoom binoculars, i.e. equipped with a system for smoothly changing magnification, here from 8 to 20 times or from 10 to 30 times. 50, of course, means the diameter of the lenses.

Question : Does the set include a case and a strap to hang the binoculars around the neck?

Answer: Yes, each binocular has a case and a neck strap, usually also caps for the lenses and glasses, unless it is expressly written that it does not have one.

Question : What effect do the magnification and diameter of the lenses have on the image of the binoculars?

Answer: The higher the magnification , the greater the visibility of details, but also the lower the surface brightness of 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 we usually choose binoculars with high magnifications, around 15-20x or zoom binoculars .
In turn, the larger the diameter of the lens, the greater the resolution of the binoculars and the brighter the image, but also the greater the weight and dimensions of the binoculars, sometimes requiring a photographic tripod.

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

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

Question : Is it better to choose fixed magnification binoculars or zoom binoculars?

Answer: Zoom binoculars are equipped with an additional optical system that allows you to change the magnification. In optics, "less is more" often. Each additional optical system, which is not a corrector for 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, zoom binoculars offer greater versatility, because no one carries 2-3 binoculars with different magnifications.

Question : Does this binocular have glass lenses or plastic ones?

Answer: All good binoculars have all-glass optics, because only glass can be ground and polished to the appropriate shape, while polymers ("plastics") have a precision limited by the accuracy of the forms.

Question : In the specification you write about anti-reflective / anti-reflective layers, what is it? Are the anti-reflective layers there to make me invisible, i.e. to prevent the binoculars from giving off "reflections", e.g. from the sun?

Answer: Anti-reflective layers, also called anti-reflective layers, are used to increase the efficiency of an optical system, for example binoculars, but basically any other device. Optical efficiency determines what percentage of the beam entering the optical system passes through the system. You need to know that when light falls on the boundary of two optical media, e.g. glass / air, a certain fraction of the beam is reflected. We know from everyday experience that you can see yourself in the glass - for this very reason. To minimize losses, anti-reflective layers are used, thanks to which more light passes through the boundaries of the media and less is reflected.
Anti-reflective layers can be of various types and classes, and they are often the reason for the price of the best binoculars, whose total efficiency can reach up to 95%.
It is worth knowing that anti-reflective layers are applied to the optical surfaces of elements of microscopes, telescopes, spotting scopes, sights, photographic lenses or night vision devices for the same purpose as in the case of binoculars.

Question : When describing binoculars you write about prism glass, BK7 and BaK-4, what do you mean?

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

Question : I did not find some parameters of the binoculars in the description that I found on other websites. Can I find out what brightness these binoculars have and what twilight efficiency it has?

Answer: For clarity of description, we usually do not provide secondary parameters that do not provide 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 objective diameter by 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 also the square of the exit pupil (exit pupil: see above); for 10x50 binoculars the exit 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 the magnification and the diameter of the objectives; If we have 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, which one should I choose?

Answer: There is no simple and short answer to this question. Astronomical binoculars are simply very good binoculars. This means very good correction of optical defects (mainly chromatic aberration and edge distortion) and high optical efficiency. For these reasons, we do not recommend zoom binoculars for astronomy, with perhaps a few exceptions. Astronomical binoculars do not have to have high magnification - that's what a telescope is for, to make observations at high magnifications. Binoculars - usually - should be handy so that you can always take them with you when you cannot take a telescope with you - then we choose 7x50, 10x50 or 15x70 binoculars. Typically, large binoculars dedicated to astronomy, such as 20x80 and 22x100, constitute a separate class of optical instruments that require observation from a tripod.
For a beginner observer, astronomical binoculars are used to learn about the sky, the colors of the stars, and find the brightest deep sky objects. For an advanced observer, large binoculars are a very efficient device for observing comets, variable stars, nebulae, star clusters and galaxies.

Question : I am looking for binoculars for a yacht / kayaking / fishing / sea trip, which one should I choose?

Answer: Water binoculars must be waterproof, filled with nitrogen and should have a 7x magnification, because only this magnification guarantees a bright and stable image.

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

Answer: For bird watching, we usually recommend binoculars with constant low or medium magnification, i.e. from 7 to 12 times. The optimal set for a bird watcher is binoculars with fixed magnification and a telescope with zoom on a photographic tripod.