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Posted by David McCall on 08/20/07 19:59
"peter" <nospam@nospam.com> wrote in message
news:qJIxi.1848$dz3.1743@trndny01...
>I have a cheap video tripod head that would tilt forward if the camera is
>already slightly tilted forward, and would tilt backwards if the camera is
>already slightly tilted backwards. The only way to cope with this is to
>increase the tilt friction. But this makes it harder to tilt smoothly; it
>would jerk. I'd like to balance the camera so that the tilt friction can be
>reduced to near zero.
>
> The more expensive tripod head have a sliding plate to move the center of
> gravity of the camera directly over the pivot point. I don't see how this
> solves the problem. As long as the center of gravity is *above* the pivot
> point, the problem is still there. The solution should be to make the
> center of gravity lie on the same axis as the pivot point, and the only
> way to shift the center of gravity there is put a counter weight below the
> pivot point. This is like balancing a wheel; if one side is too heavy, you
> put a weight on the opposite side.
>
> But I have not seen any such counterbalance on any videographer's tripod.
> So I wonder what the established solution is.
>
> Another possible solution is to use more complex mechanism to create a
> virtual pivot point inside the camera body where the CG is?
There are pan and tilt heads that do allow you to balance a camera
perfectly,
but I think they are all pretty expensive even by professional standards.
The horizontal pivot is pretty much like any other head, but the vertical
pivot point is mounted on an L shaped bracket that is adjustable.
Then the camera rides on a little swing that is also adjustable.
By adjusting the positioning of the swing and the plate you
can move the camera to a position where the pivot points are
at the center of gravity allowing the camera to hold it's position
at any angle with any amount of drag you choose.
there are pictures of such heads on these pages
http://www.essanay.com/Cranes&JibArms.pdf
http://www.ronfordbaker.co.uk/fluid_heads.html
You wouldn't believe how much time it took to
find these pictures. I was hoping for better.
More common is the traditional head with an internal
spring that will return the camera to a neutral position
if you let go with no drag applied. If you have the
right spring, or your head that is made to match your
camera's weight, then you should be able to let go
with a small amount of drag applied.
The counter balance below the head idea would
work but it would limit your movement so much
that it wouldn't be very practical. A small amount of
pan or tilt would cause the weight to run into the
legs of the tripod.
David
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