Загорский оптико-механический завод (ЗОМЗ) холдинга «Швабе» представил два новых изделия − бинокль большого увеличения со стабилизацией изображения БСФ 20x50 и малогабаритный бинокль БПФ 8x20.
The Zagorsky Optical and Mechanical Plant (ZOMZ) of the Shvabe holding presented two new products − a large-magnification binoculars with image stabilization BSF 20x50 and a small-sized binoculars FPF 8x20.
For those not familiar with the terms for optics the first number is the magnification and the second number is the width of the lens you point at what you are looking at, so 20 x 50 means each of the two lenses pointed at the target are 50mm across and the magnification is 20x, while the smaller binoculars are 8x20 which means 20mm objective lenses and 8x magnification.
The larger the magnification the closer everything appears... it does not make things appear bigger, it makes them appear closer so with a 20x magnification an object that is 100m away appears to be 5m away.
The more powerful the magnification the harder they are to hold steady but the 20x binoculars have autostabilisation system built in to make them easier to use.
If you divide the objective lens by the magnification you get the exit pupil diameter... the exit pupil diameter is the diameter of the focused image.
Normal human pupils are about 5mm but in the dark can be 7mm so exit pupil diameters of less than this makes the focused image hard to see... it appears wobbly and in and out of focus.
The smaller the objective lens the lighter and more compact the binoculars are, but it means they let in less light and are less useful in low light or dark conditions.
Big objective lenses give a better view at any distance, but make the binoculars bigger and heavier and more expensive.