what is the formula for counter balancing the jibs?
 

Jony Jib here, what is the weight of camera to counter weight ratio?

I could have sworn it was 2.5:1 weight to camera.


any thoughts?

I'd have thought it was entirely dependent on:
ratio of : distance from pivot-point to camera divided by distance from pivot-point to counter-weight. (assuming minimal friction at pivot-point etc, and pivot-point is nominally at CofG of the whole rig etc etc)

ok, so lets say I have a 10lb camera and the pivot point is 12 feet away from the camera and the weight is 4 feet from the pivot point.


would that mean 12/4 = 3 x 2.5(10lbs) or 3 x 2.5 x 10 ?


thats 75lbs either way.

so I'd need that much?

Your counterweight would be about 30 lbs.

The equation is:

(Distance Camera-to-Pivot)
-------------------------------- X (Camera Weight) = Counterweight
(Distance Pivot-to-Counterweight)

So in your case:

(12 feet / 4 feet) x 10 lbs = 30 lbs

Keep in mind this equation just gives you a ballpark number and does not take into account the weight of the jib arms. The actual weight will be a little more.