Binocular construction can be in many ways. And one kind is not better than the other.
It does come down to a mfrs. decision, and there are many things that may determine that.
The list of chassis component types, include: Aluminum, fiberglass reinforced polycarbonate,
carbon fiber, and magnesium. Some older types may include some other metals.
The carbon fiber models are not very common, but Nikon offers models, in all 4 types mentioned
above, and Ferrari, a car company that uses carbon fiber, in their F1 race cars, and also
in their production cars.
Here is one carbon fiber binocular model that I own, the Nikon Travellite 5 8x25, and a Ferrari model
I would like to own some day. The binocular may be just as allusive as
my getting the car.
Jerry