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Message: <blockquote data-quote="Holger Merlitz" data-source="post: 3393158" data-attributes="member: 84262">Only with Porros there would be sufficient space to swing a lens in- and out of the light path.In principle, an objective zoom would be possible, too, using a floating group of lens elements. It could be operated via a single central wheel just like the focuser. However, these lenses would be quite heavy, and there has to be enough space for them to float, plus space for the focusing lens, so I fear that the central objective zoom would be impracticable because it would lead to fairly long and heavy binoculars.       Cheers,Holger</blockquote>