# What is a “Center Of Mass” issue of a Gorillapod?

I read somewhere that a Gorillapod may have "Center Of Mass" issues when used with the long lenses.

So, I wish to understand what is a "Center Of Mass" issue?

I have to clarify that I am NOT a physics student nor I ever intend to be. Answers in a layman's language would be appreciated.

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No terrifying formulas please. :) – TheIndependentAquarius May 24 '12 at 7:03
You're certainly welcome to ask for a simple explanation, but I just wanted to remind everyone that this is ostensibly an expert-level site: we reserve the right to use formulas when it's appropriate to do so ;-) – David Z May 24 '12 at 7:38
Long lenses often (typically?) have a tripod attachment point at a point just short of half-way to the end of the lens. The center of mass of the lens is at half-way, but the tripod attachment point is placed where the center of mass of the lens+camera (sorry, equation!) might be, for a typical camera with which the lens might be used. Given such an attachment point, the location of the center of mass is probably not too much of a problem, however long lenses are also relatively heavy, and a gorillapod is intentionally very light, and that can be a problem in itself. – Peter Morgan May 24 '12 at 11:30
If you want physicists to help you, then perhaps you should think twice before calling their bread-and-butter "terrifying"... – ptomato May 24 '12 at 12:48
@AnishaKaul: Would you feel equally confident saying "I cant read so good, please, no scary big words! Ha ha!" It's appaling that there exist people who are illiterate regarding mathematics, and it's appaling that they aren't doing anything about it. – Ron Maimon May 24 '12 at 19:10

It is hard to guess without seeing Gorillapod in use, but my guess would be the following:

Center of mass could be understood as an average position of the mass of the object. In order for an object to be in stable equilibrium, its center of muss must be vertically above the area, which is enclosed by contact points of tripod's legs with the ground. If you use elongated objects, center of mass is far from the point where camera is attached to the tripod and there is large likelihood that it won't be above the specified area, meaning that the tripod together with the object could fall over.

The point is that tripod is designed in a way that center of mass of the object it supports is fairly close to the attachment point, and of long lenses this is not so.

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Thanks for replying. I have added the link for the Gorillapod in the question. Will this problem of center mass not be same for all tripods of this height? – TheIndependentAquarius May 24 '12 at 7:29
Yes, assuming the legs of the tripods cover roughly the same area and meet the ground at the same point. – Vortico May 24 '12 at 7:33
Problem of center of mass exists for any tripod and for any object who has relatively high center of mass and relatively small area of contact with the ground (humans are very prone to center of mass problem, dogs aren't). – Pygmalion May 24 '12 at 7:33
Your last comment was helpful, Pygmalion. Thanks. – TheIndependentAquarius May 25 '12 at 5:11

Continuing from Pygmalion's answer a graphical explaination can be as below
(Warning! - Representation may be a bit wierd and out of proportion)

Initially without the camera this is the case

After camera with long lenses is placed the COM (centre of mass) shifts upwards and outwards as below

This might be the "Centre of Mass" issue you are talking about.

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thanks for the diagram. – TheIndependentAquarius May 25 '12 at 5:12

Stand on your tiptoes and hold your hands out. You will discover what center of mass issues means. Basically gravity is pushing down on the camera/lens and it needs to be supported directly underneath where gravity is acting (center of gravity).

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thanks, that too was helpful. – TheIndependentAquarius May 25 '12 at 5:12

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