Aha Trivia Stuff Everyone Should Know
Aha Trivia: Stuff Everyone Should Know · ahatrivia.com/mb-bird-study-250cbff4bfe1

What does the second number on 10x50 binoculars tell you?

The lens diameter.

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  1. The tripod height
  2. The lens diameter ✔
  3. The bird's wingspan

Why: The second number is the objective lens diameter, which affects light gathering and image brightness.

Huh, didn't know that: The second number is the objective lens diameter, which affects light gathering and image brightness.

The dad joke
Bigger lenses brighten the view, no kidding!
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References

Answer: The lens diameter. The second number is the objective lens diameter, which affects light gathering and image brightness.

  1. Scouting America: Bird Study www.scouting.org/merit-badges/bird-study
    Explain what the specification numbers mean on binoculars
    Checked 2026-11-07.

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