The second number, e.g., 10x50 → 50 mm is the front lens diameter.
Larger lenses gather more light → clearer images, especially in low light.Types include coated, multi-coated (MC), and fully multi-coated (FMC).
Improves brightness, contrast, and reduces glare.
The width of the area you can see through the binoculars.
Wider FOV is better for birdwatching, sports, or tracking moving targets.