Astronomy Hacks

Choose the Best Binocular

See more with both eyes.

Inexperienced astronomers often think of binoculars as poor substitutes for a telescope, something to use only if you don’t have a scope. That’s a mistake. In fact, a binocular is essential observing equipment even if you own a dozen top-notch telescopes. Experienced observers use binoculars to orient themselves within the constellation when they are locating objects they intend to view with their scopes—to place the object within its context of bright surrounding stars. A binocular is also useful for planning star hops [Hack #21] because the dimmest stars visible in a standard binocular are of similar magnitude to the dimmest stars visible in the optical finder of a typical telescope.

Figure 1-4. Barbara measures her entrance pupil using an Allen wrench

Tip

Binocular is properly a single noun. Calling a single instrument a “pair of binoculars” is incorrect. “May I use your binocular” is grammatically correct; “May I use your binoculars” isn’t, unless you mean two or more instruments. (Actually, asking to use someone’s binocular is an etiquette faux pas among astronomers—nearly equivalent to asking to borrow someone’s toothbrush—because most people have their personal binoculars adjusted to their own vision. If you do borrow a binocular, don’t change the diopter adjustment.)

But binoculars are more than just an adjunct to telescopic ...