Agile Observing

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A basic pair of 8x40mm binoculars lets you access around 500,000 stars

Many people think astronomy is a complicated or technical activity. While it can be, it very definitely doesn’t need to be. Over 90% of my observing is done with a simple pair of binoculars, like these light and inexpensive 8x40s, which I try to carry with me wherever I go on local walks or further afield.

With these I can access stunning images of the Moon, resolve the satellites of Jupiter, sweep through over 500,000 stars (most too dim to see naked eye), resolve glittering star clusters like the Pleiades and Hyades, and (under suitably dark skies) view the dim light from galaxies many millions of light years away.

Marry the binoculars with a small tripod and a night sky app on your phone and you have everything your need for agile observing during clear skies or brief opportune breaks in the weather.

Clear skies.

Stargazing Essential Kit – Binoculars

Binos

Q. What’s the single best piece of astronomy equipment you can own, on a budget or otherwise?

A. Without any shadow of a doubt, binoculars.

Portable, light weight, robust and with plenty of daylight applications, a good pair of low or medium power binoculars is probably the single best investment you can make for stargazing or astronomy.

Unaided your eyes can potentially pick out between 5000-7000 stars from a dark site. With a good pair of medium powered binoculars that figure jumps to a staggering 600,000 stars!

Although binoculars don’t give you the huge magnifications that telescopes do they make up for that with stunning wide field views of star fields and clusters. Objects like the Pleiades, the Perseus double cluster, Orion’s nebula, the Hyades, Comets, the Andromeda galaxy and the Moon look incredible through binoculars.

They’re also perfect for the rapidly changing weather in the Highlands. During less settled conditions you can grab your binoculars and head outside for short bursts of observing, avoiding the pain of setting up and packing away a large telescope.

If buying binoculars for the first time, my advice is to avoid big astronomy binoculars with large objective lenses. These have their applications but usually provide poor shaky views unless adequately mounted. And once you start mounting binoculars you’re straying into telescope territory.

Here are the three standard sizes of binocular I suggest for grab and go stargazing, with 8x40s being by preferred size in most situations:

7x35s Star reach: 450,000 Field of view: 9.3 degrees
8x42s Star reach: 600,000 Field of view: 8.0 degrees
10x50s Star reach: 750,000 Field of view: 6.8 degrees

The first number is the magnification and the second number is the objective lens diameter.  A large magnification without a decent sized objective will provide dim views.  Another type of binocular to avoid are zoom models which promise large magnifications but tend to produce inferior views and are often very fiddly to use in the field.  Simple is best.

The image below gives a good average comparison between the field of view provided by a 8×40 binocular and a 25mm telescope eyepiece.  Notice all three main belt stars in Orion can be framed through the binoculars.  Perfect for learning the constellations and taking in broad sweeps of the night sky.

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