Michael, every commercial parallelogram I've examined is not up to it's listed rating. My first design, made from aluminum exclusively, worked OK, but didn't hold my 20x80mm binos securely...I experienced the "bob" just as you did. Hold your breath and don't touch them while the shaking settles-down! My second design is similar to the first, similar moments and dimensions, but made from hardwood. Solid-sectioned parts instead of aluminum tubing...and it is much, MUCH more solid. Wood dampens vibrations amazingly well, and it can be loaded to a higher factor while still retaining solidity. My newest design, for the "Schwartzenbinos", is an even beefier version. Might have it ready by Messier Marathon time. It should be noted that it is not a good idea to overload a parallelogram with a huge binocular, since if the mount fails, it can gouge-out your eyeballs or crush your skull! ;)
From: Michael Carnes <MichaelCarnes@earthlink.net>
FWIW, I've got a pair of five-pound 20x80s on a parallelogram whose rating tops out at five pounds. The things bob around like an anglerfish's lure. I can 'just' manage the binos unassisted for terrestrial stuff, but you'd need twice the mount I've got for them to be truly usable at night.
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