Glenn NK Offline Upload & Sell: Off
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Roland W wrote:
There are no standards for how to come up with load ratings for tripods, so you can not just look up the rating and say how much more rigid a set of legs is.
This is correct, and defines the problem.
Load ratings are mostly useless because strength is rarely if ever the problem. I've seen a picture of a large man being suspended from a tripod - it didn't break.
The important feature of a tripod is stiffness, which although somewhat related to strength is not the same thing. Stiffness determines how much the camera will shake or vibrate - more stiffness, less vibration/movement.
Consider hanging a weight from a thread or a rubber band. The rubber band will likely hold up more weight (strength) before it breaks than will the thread, but it will stretch (deform) more than the thread.
The rubber band has strength, but no stiffness. The thread has less strength but is stiffer.
For a given material (CF or aluminum), a larger diameter will be stiffer (it will also be stronger).
Stiffness is inversely proportional to length - longer legs = less stiffness.
Glenn
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