Ok man.
Let me work it out for u,
First u have to understand a few things.
1. Force = Weight x Gravity (Newton), Here is the weight of the camera
2. Stress = Force / Area ( Pascal ) measurment of strength of the material
3. So here the stress will be the force acting on the smallest section of the ball head. where Area = Pi() * Radius^2
R^2 is the radius to the power of 2
Here in this case
First Position - Landscape.
The ball head is expected to be loaded in compression.
Therefore Stress Compression = F/A = F/PI() * R^2
Second Position - portrait.
The ball head is expected to be loaded in bending and direct shear.
Therefore Stress Bending = My/EI
As the Moment is very small, the length from the center of mass to the center of ball head is small Stress, so bending can be assume to be 0
and for Direct shear works like the one in compression Stress Shear = F/A
So if the allowable stress is the same
Thanwe get Sc = Ss which is the same...
Arh.... no getting any where hahaha...
Using Standards Allowable factor
but than if we include in the equation the industry standard stress ratio it will change the allowable stress factor ...
From standards,
Compression Stress Allowable = 0.6 * Allowable stress
and Shear Stress Allowable = 0.4 * Allowable Stress
SO........... we are getting somewhere
0.6:0.4 arh,,,, reduce the ratio to 1 we get 1: 0.666 so it is about half....
the Auntie is quite right.... my god she is good...
Conclusion
But than again we are not really sure if that is the way the ball head's max load is rated, acting in the landscape direction...
If i am the one doing it I will have just gone with the lower result as the maximum loads....
So no worries.