Clarity and brightness - Binoculars
The clarity and brightness of the image viewed through the binoculars is largely determined by the magnification factor and the diameter of the front lens. (See Brightness). Binoculars with a high level of clarity and brightness are recommended for use in poor to moderate light conditions.
Bear in mind that the twilight factor is just as important as the clarity and brightness factor. Clarity or brightness increases when the magnification factor is lower. After all, clarity is the square root of the exit pupil, which is calculated by dividing the front lens diameter by the magnification factor (see Exit pupil). However, if you use the binoculars with a high brightness and clarity factor and with a low magnification factor to focus on the details of a sign situated further away, for example, you may not be able to read the writing on the sign whereas, the binoculars with the higher magnification factor and the lower brightness and clarity factor allow you to read the sign just as if you were using reading glasses to do so.
It is worth bearing in mind that even the best night vision binoculars will throw in the towel at some point. When it gets dark, it is time for an image intensifier.
So far, the difference in brightness and clarity caused by inferior optics due to a partial lack of coating or the application of a low-grade coating has not been taken into consideration at all. This greatly affects the final image quality. In the example below (admittedly this is computer-generated but it still gives you an idea), you can get an idea of what the difference can be between good and poor binoculars with the same theoretical values of brightness and clarity and magnification. To be sure, a difference in brightness and clarity and image details caused by lenses and coating of an inferior quality, for instance.