You are observing an optical illusion. What you call “resolution: is focus depth of field. Because you are looking through the binoculars backwards, the aperture (the hole that lets in light) is the small eye hole, like a camera on f8.
When you look through the binoculars properly, the opening is the large end, which makes a large aperture, This is to let in as much light to be magnified as possible. But it makes it like a camera on f1.2
Large aperture, small depth of field
Small aperture, greater depth of field.
You can read here about f stops