Term - Relative brightness | 
| Relative brightness | SWPP Photographic Glossary | Tuesday 4th November 2025  | 
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 Relative brightnessIndicates how good binoculars are in low light. To find this divide the objective lens by the magnification and square the result. A 10x40 has a relative brightness of 16 (40/10= 4, 4x4=16). A higher number means the binoculars will be better in low light situations. 
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 Information provided by: SWPP  |