Haiku brought up this topic about telephoto and zooms and that made me think about binoculars or telescope on the boat. I’d also like to use them from my window here over the valley.
This explained it to me in better detail:
Binoculars are identified by 2 numbers. The first is magnification power.
Example: 7 x 35 binoculars have a magnification power of 7.
A magnification power of 7 means that an object will appear 7 times closer than it would to your unassisted eye. For example, if you view a deer that stands 200 yards away from you through 7x binoculars, it will appear as though it were 28.6 yards away (200 divided by 7).
Be aware that binoculars with magnification powers greater than 10 amplify the movements of your hands, making steady viewing difficult.
Binocular Objective Lens Diameter
The second number used in binocular identification refers to the diameter (in millimeters) of the objective lenses (those farther from your eyes; those closer to the “object” being viewed).