Hand anyone a pair of Porro-prism binoculars and they will instinctively hold them by the prism housings, but there are no circumstances in which this is the steadiest way to hold them.
If you are looking at objects close to the horizon, such as a rising Moon, hold them by the objective tubes; you’ll immediately notice how much steadier they become. However, for objects high in the sky, we need to give more consideration to ergonomics.
Blood-flow to our arms is reduced when we raise them higher than our hearts, quickly leading to fatigue and, consequently, an unsteady view of the heavens. The holding system – i.e. us – needs shoring up. If you can rest your elbows on something stable, such as a fence-post or the roof of an automobile, that will help, but these things are usually not conveniently located.
If you hold your hands up to your eyes, as if to shield them from light coming from the sides, you will find that the interphalangeal joint (first knuckle) of your thumb, fits comfortably into the outside corner of your eye socket, with the proximal phalanx (second thumb-bone) resting comfortably on your cheekbone.
If you hold binoculars in this position, with your first two fingers around the eyepieces and the other two fingers around the prism housing, they will immediately become steadier because each arm has become locked into a stable triangular structure.
The higher we aim, the more weight is taken by our heads, which confers even more stability, especially if we are reclined with our heads supported. It does make focusing difficult, but we shouldn’t need to refocus when we use binoculars for astronomy. It initially feels awkward, but it is so superior that it soon becomes second nature.
We can make it steadier still. If you’ve ever done target-shooting, you are probably aware of the “hasty sling” method of steadying a rifle. We can use a similar principle to binoculars. Hold the binoculars so that the strap loops down. Place both arms through the strap, so that it comes just above your elbows. Hold the binoculars in the most comfortable way you can and brace it “solid” by pushing your elbows apart. It’s extremely effective, but a bit awkward to get into, so you’ll probably only want to do this when you need extreme stability.
For larger binoculars, and for better stability for all binoculars, the solution is to mount them, which we cover in other articles at AGT. Happy observing!