The toughest parameter to predict (1 Viewer)

I've gotten a lot of practice eyeballing things at auction or on the shelves,
but the one property that deals me a lot of surprises is:

---> handling/shake.

I've seen oddly twitchy 7x35 units, a surprisingly stable 10x25 easily braced with hands and forehead, a steady 7x50 and a shaky one, jittery 8x30s and calm ones that looked almost the same.

I can see some shape properties that go with stable handling and good scanning but I can't usually tell a winner from a twitcher. You can see a nice mono-curved top, but not the weight distribution..

Interesting, I also found a tiny leitz 10x25 trinny surprisingly stable, whereas I usually can't cope with any 10x, far too much shake, but I can't recall having a problem with 7x, and I find most stable of all is that old Sard 7x50 BU Aero, weighty, well balanced, nice grip around the tubes, and with those big winged rubber cups jammed around the eyes it does not move a fraction, love using it in the garden but you couldn't go out with it these days could you.