| Planning on using your binoculars in low light conditions, | | | | basically the second number by the first in the |
| such as at dusk or at dawn? If so, when you buy your | | | | specifications. For instance, a 10x50 specification would |
| new binoculars you'll want to look for some specific | | | | indicate an exit pupil of 5. The rule of thumb is to use |
| qualifications to ensure that your vision won't be | | | | an exit pupil that is the same size as the human eye. |
| compromised. First, check the lens coating. If the | | | | During periods of low light, the human eye's pupil |
| binoculars are listed as fully multi-coated, this means | | | | expands to five to seven millimeters, to maximize the |
| that there are multiple layers of lens coatings on all | | | | amount of light that can be collected. Thus, you'll want |
| lenses and optical pieces. This is important because | | | | to choose a binocular with an exit pupil of five to |
| the lens coating is what cuts down on glare and allows | | | | seven millimeters as well. |
| the most light possible to enter the binocular. The | | | | You may see some binoculars with a twilight factor |
| amount of light affects the brightness and clarity of the | | | | listed. This complex mathematical formula can be used |
| images you see, so during periods of low light you | | | | along with the brightness index, or overall light |
| want to maximize the amount of light that is taken into | | | | transmission, to determine how well the binoculars will |
| the binoculars. | | | | perform in low light periods. By also considering the |
| Additionally, the exit pupil is a very important indicator in | | | | lens coatings and exit pupil, you should have a pretty |
| how well the binoculars can function in low light. The | | | | accurate idea of how well the binoculars will perform in |
| size of the exit pupil can be determined by dividing the | | | | low light. |
| size of the objective lens by the magnification size, or | | | | |