Twilight factor is computed by multiplying the objective lens diameter by the magnification and then taking the square root of this product. Thus an 8x42mm binocular has a product of 336 (8x42=336). The square root of this is 18.33 (√336=18.33). This number may seem reasonable when comparing an 8x42 pair of binoculars with a twilight factor of 18.33 with an 8x25 pair with a twilight factor of 14.14. The twilight factor really only comes to play when looking for binoculars to use during twilight or for astronomy. Again, this formula also doesn't consider the optical quality that has a tremendous impact on the perceived brightness of the optics.

The Vivitar binoculars can be found in both universal stores such as Walmart and Target, and professional optics stores across the country. And, while some of the pieces are made locally, in the United States, a part of the production remains outsourced overseas, especially in China and Korea. Surprisingly magnification is not too big a deal for large, stargazing models. Seeing as those stars are literally light-years away, you likely won't notice the difference between 10x and 12x. These bins are meant for gathering light and making things brighter rather than bringing them closer. If you really want to feel close to the cosmos, you'll have to go with a telescope (or fill your phone with Neil deGrasse Tyson podcasts). Glossary of Terms The target must be hung on a stable object i.e. tree or wall and it should be 100 meters away from you. The distance of target will depend upon the magnification power your binoculars offer. If your pair offers 10x then 100 meters, if magnifying power is 5x, a 50 meters distance will be fine. In the end, it all narrows down to your budget and expectations. If you’re looking for a pair of binoculars to help you see your favorite sports event, theatre play, concert or even the Moon from afar, Vivitar is the right option for you. OptRep specialize in repairing binoculars and many other types of optical equipment including spotting scopes, telescopes and other and ophthalmic instruments.Located in Selsey, West Sussex, they are a small British company run by enthusiastic optical technicians that have been working with optical equipment since 1960. Similarly, if the target is significantly higher than usual, start loosening its screws until it merges with the other. Step 2: After opening, take the cotton bud and clean it from inside. You can use a blowing brush too. Do not forget your binoculars at home. This is poor form every time. Are there any other things that you think are important to consider when choosing a product that we didn't cover? It wasn't until the middle of the 19th century that people started using prisms. The first prisms used were the pro prism, invented by Ignazio Porro. The Porro prism allowed for the long focal length of the Keplerian Optics by folding the optical path. By combining two pro prisms, it increased the focal length while flipping and righting the object. This allowed for a more compact and manageable size. The double Porro prism gives most older binoculars that classical look.

Why spend the entire night forcing your eyes to see the stage when you can enjoy a first-row experience with the help of a good pair of binoculars? And, if you also want to take pictures or record a video at the same time, you can do it with only one piece of equipment instead of two. Unless you are really attached to a pair of binoculars (which I can totally understand), or if they were a cheap pair to begin with, it is sometimes just not worth having them repaired or serviced. If this is the case then it is time to get yourself a new pair of optics.For all those looking to keep their profits locally, the Vivitar brand may seem like a good option. The Vivitar Corporation is a manufacturer, distributor, and marketer of optical and photographic equipment headquartered in Santa Monica, California. It was founded over 80 years ago, in 1938, and originally branded as Ponder and Best, after its founders, Max Ponder, and John Best.

It is perfect for nature lovers, pro scouts, theatre enthusiasts or those who want to see wild animals in their natural habitats. The multi-coated lenses ensure clear and sharp views in almost all lighting conditions, meaning the binoculars are a great choice for adventurous and outdoor people.You can easily identify the size of the lens in millimeters after the “x” symbol in most binoculars specifications. In other words, a pair of binoculars that says 8×40 means it magnifies images up to eight times and features 40mm lenses that allow enough light coming in. Focusing: Ease of focusing is an important factor to consider when choosing a pair of binoculars. When evaluating focusing, most binoculars use a central focusing knob that you turn while looking through the optic. Getting the sharpest focus possible may require very fine adjustment. This can be done in several ways. You can increase the number of revolutions that it takes to focus, making the adjustment finer. This slows down the focusing process. Extra time needed to focus can mean the difference between getting a good view of a moving object or not. The overall construction of these Vivitar 10 x 25 digital camera binoculars feels sturdy, reliable, and lightweight enough at the same time so as to not cause hand or wrist fatigue even when operated without a tripod. Affordable and reliable, the set represents the perfect gift for children and adults alike who want to see objects from afar but still need to practice with various characteristics and functions, including focus.