Focusing with Binoculars for Stargazing
Part of the Stargazing For Dummies Cheat Sheet (UK Edition)
If you use binoculars for your stargazing, you need to get them into focus before you begin. Once your binoculars are focused, the stars you see should look incredibly sharp. You can focus most binoculars in the same way. Just follow this simple step-by-step guide:
Adjust the separation between the two eyepiece lenses so that they’re at the same spacing as the distance between your pupils, called the interpupillary distance.
You can usually adjust the separation by holding both halves of the binoculars and physically twisting them apart or together.
Point your binoculars at something bright but distant.
A planet or a bright star like Sirius or Canopus works well.
Have a quick look through.
You never know; they may already be in focus!
Close the eye that looks through the eyepiece with an independent focus.
You may find it easier to put the eyepiece lens-cap back on so that you don’t have to squint.
Adjust the focus until your target looks sharp for your left eye.
Use the focus ring normally found at the top of the binoculars on the bridge between both halves.
Close your left eye and open your right eye (or swap the eyepiece cap onto the other side) and adjust the focus for your right eye using the eyepiece focus, called the dioptre corrector.
The dioptre corrector is for people who have two eyes of slightly different strengths.
You’re now good to go, but keep in mind that everyone’s eyes are different. If someone else uses your binoculars, you may have to repeat the focusing process to get them back in focus for your eyes.