Letcase binoculars are actually two identical symmetrical telescopes mounted together. Because they point in the same direction, they allow the observer to see a greater distance than with the naked eye. Binoculars have a big advantage over a single telescope because you can see them through your eyes and hold them more easily with your hands.
Optics
The objective diameter usually determines how much light is allowed, and the magnification will show the ratio of the focal length. An example is 8 x 35 (8x magnification and 35mm objective diameter) or 7 x 50 (7x magnification and 50mm objective diameter). In both cases, the first one has a higher magnification (8 to 7) but allows less light (35 mm less than 50 mm) than the second. If you need binoculars for low light, purchase the largest objective diameter.
Lens structure and coating
Unfortunately, in any optical instrument used for images (eg, telescopes, cameras, microscopes, etc.), light is often reflected and distributed into the view. This can reduce the contrast. Reflection can be reduced by adding a coating to the optical system. Some of the latest technologies are phase correcting prisms and dielectric prism coatings.
Letcase binoculars designed from Porro prisms are usually brighter than roof prism designs, but newer technologies are reducing the difference (Porro prism binoculars still have the highest value at a lower price).
Select binoculars
Roof prism models are usually lighter and smaller than the Porro model, but usually pay more. If the binoculars are sealed and filled with nitrogen, they will not condense into clouds.
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