Articles
How to choose low light conditions binoculars?
2. Basic parameters
Every binoculars can be described by three most important parameters:
- objective lens diameter
- magnification
- field of view
Taking low light conditions into consideration, the last parameter (field of view) is the less important. However sharp to the edge and wide field of view makes our observations more comfortable not only at night but also in other hard conditions.
Objective diameter and magnification give us a recipe for another physics value, so-called: “exit pupil” This parameter show us the dimensions of casted ‘light circle‘, created right after the eyepiece and heading towards an eye. It can be easily measured directly but precise and easy is just to divide objective diameter value by magnification value. A smart reader can easily notice that ‘exit pupil’ in typical night-using binoculars equals 7mm (7x50, 8x56, 9x63).
