On 12/14/2015 9:21 AM, Charles Geilfuss wrote:
I have one of those made out of a small pillow case filled with $3 of dried
beans. Rice works well too.
Ahhh, nostalgia. This was a frequent subject here in the past. A few
comments/thoughts/memories:
For bags, location is crucial. Hanging it from the tripod helps suppress sympathetic vibrations IN THE TRIPOD. As Ken
points out, it does nothing for vibrations in the body, lens/body connection and lens. I recall testing/speculation/??
here that the lens mount, with the heavier lenses, created a pair of weights not rigidly coupled, with its own vibration
modes.
Supporting evidence for the above is partly forgotten, probably partly lacking. There are two clear evidences, both
courtesy of Gary Reese and his lens tests.
1. For longer lenses, he conducted his tests in an ice rink. AND, melted the tripod legs into the ice and let it
refreeze. It did little to no good for the long, heavy lenses.
2. He tried various combinations of lens support, Bogen Lens Support, two separate tripods for camera and lens, tripod
and monopod. None of them completely stopped the vibrations, as he didn't discover until later. He later wrote that he
had found using these lenses in the field resting on vibration suppression bags on large, solid objects, that the optics
themselves were considerably better than his formal tests had indicated.
3. I know less about this. I have seen on the web the making and use of counterbalance weights for specific camera/lens
combinations, with the weight hung under the camera body or behind and under. I recall test shots, but not brand of
camera, lens models, etc.
And - it's not just weight, it's also means of use, mass of filling, size of filling elements and friction between them.
Where do you think the mechanical energy of the vibration goes? It goes into heat, which is why the amount of friction
between damping elements is important. The reason that CF tripods and wood tripods are so much less affected by
vibration than metal, from camera operation, wind, etc. is that they have much more internal friction in the material.
Obviously, sheer mass makes a difference, as do the frequency of the vibration and internal characteristics of the
specific material.
Locally gathered material, rocks, dirt, sand, etc. in a bag will naturally vary in effectiveness for over or under
lens/camera. For tripod hanging, it's just about total weight.
From least toward most effective for over or under lens/camera use:
Styrofoam - just too light.
Beans - too light and low internal friction (depends on the beans, too)
Rice - A little denser and better internal friction
Sand - more density and better internal friction. Moderate vibration just
disappears into it.
Lead shot - As I recall, uncoated bird shot was best, super dense and lots of internal friction. Coated is healthier,
but less friction.
Didactic Memory Moose
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What if the Hokey Pokey *IS* what it's all about?
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