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Old May 1st, 2010, 11:24 PM   #16
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Randy... I opened the file and got a good look at it.

Because the camera's moving around a lot (zooming and panning), it's much harder to pick out a target to stabilize the entire clip.

Also, is the footage interlaced? It's harder to track interlaced footage. Not impossible, just tougher. The vibration is at a frequency that's higher than the frame rate so what you're seeing is more of a blur than a shake. In my opinion it's extremely hard, if not impossible, to remove what you're seeing. And even if the image is stabilized, you're still left with the motion blur.

If a procedure is developed to remove the vibration, the cost would be prohibitive.

Best option: reshoot with a camera that's on a platform that's not vibrating. Isolate the camera on something solid. Weight down the tripod legs with sandbags. Putting more mass near the camera gives it more inertia and it will be less likely to be influenced by external forces.

Or... get the camera further away from the speakers.

Set it up during a sound check just to make sure.
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Old May 1st, 2010, 11:57 PM   #17
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Thanks Dean... The footage is interlaced.. what you have said is what i had feared..

I have found the nature of vibration when filming bands to be hard to predict and solve.. In this instance the tripod was on the floor and from past experiences i had found this better than using a riser or a table.. Although as im discovering its still hit and miss.. Given the layout of the room the positions we had were the best by far for the film aspect and im happy with that side of it, just the vibration obviously is the prob.. We werent able to go further back because the bar was right behind me...

I didnt use sandbags although its something id like to try.. How would you suggest to use them, just around the feet of the tripod or somewhere else ?

Also as a different approach, do you think it would be worthwhile trying something to dampen the feet on the tripod ? I thought about getting some foam (maybe something shock absorbant) and making some fairly thick glove type things to go around them.. It might make the tripod a bit less stable but the foam should absorb the vibration somewhat and i could handle a bit less stability in exchange for no vibration..

Unfortunately we cant film again, this wasnt intended for anything too important though so its not the end of the world, although i want to work out how to avoid this next time because it does ruin things.. The strange thing is we had a camera on the other side getting the mirror image, it was placed in a similar spot in relation to the speakers and it really didnt suffer the vibration at all ? It's made me wonder about the nature of the problem and just how to fix it..

Also Its done at 1080i but id be happy to drop it back to SD if it would make a difference.. Would lowering the resolution help it do you think ?

Perrone.. If you have any suggestions id be grateful.. If software could remove some of it that would still help..
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Old May 3rd, 2010, 01:00 PM   #18
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The foam on the feet issue has been discussed before, and I find it can work in some situations.

I prefer the sand bags idea, but take it a step further, and also place some under the tripod feet.
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Old May 3rd, 2010, 02:42 PM   #19
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Randy...

You weren't on a concrete floor, I'm guessing.

Placing foam under the tripod might reduce vibrations coming up the legs but it might also reduce the stability of the tripod, depending on the type of foam used. You might look around for some sort of elastomeric substance that will absorb vibrations without being too soft.

Place the shock-absorbing material on the floor, the place something hard atop the shock absorber, then put the tripod on that. The hard material can be 3/4" plywood. Doesn't have to be the whole sheet. In fact using a sheet might create more problems as it can also pick up the acoustic vibrations you're trying to isolate. You can probably make a three-way "spider" with anchor points that fit the tripod's feet or spikes. The spider sits on the elastomeric material. It's lighter. Easier to transport. And unlikely to pick up much of the vibration itself.

Try placing the sandbags higher up on the tripod. Make a loop of rope or strong cord that will sit about halfway up the tripod, then suspend the sandbags from that, with the sandbags resting against the legs. It should help dampen any vibrations coming up the legs.
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Old May 3rd, 2010, 10:34 PM   #20
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What about trying the pads that you put under studio monitors to isolate them from your desk??? Just an idea, and you'd need 3 of them, but it might work if you put a sheet of plywood on top of the pads and put the tripod on the plywood- oh yeah, put something heavy on top of the plywood too while you're at it. Maybe a few sandbags or a couple of barbell weights. Or even a 5 gallon pail of water in between the tripod legs. Should be heavy enough.

I think the two keys to damping resonance/vibration are elastic suspension and mass. In fact it isn't necessary to damp all motion, just to shift the frquency of vibration down to where it is slow enough for stabilization software to work correctly.

We run into these kinds of issues all the time in designing the read/write actuators for tape drives and the trick is always to shift the resonant frequency of the system so it's lower than the frequency at which we drive the actuator up and down. So getting the resonant frequency down under say half the frame rate or thereabouts might be good enough
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Old May 3rd, 2010, 11:19 PM   #21
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Dean...It was a wooden floor, but strangely my friend filming on the other side had almost the exact same conditions but didnt get hardly any vibration ??

What you are saying about the shock absorbing material and the panel on top of that is what im working towards.. I just want to find out the most effective shock absorbing items to use under the panel.. Ive seen various bits of foam and other things like air springs and all look to have some ability but my hope is to navigate through the options as best i can before i start spending otherwise i might end up with a bunch of things that dont work that well and wasting money..

Jim.. Ideally id like to take the idea of using software out of the equation. Its my hope to get it stable enough across most scenarios i encouter so that the footage is looking good straight from the shoot.. I am fairly confident i will get something working, just how effective and how many rounds of trial and error is the question..

The problem for me is, live rock music is loud and has many frequencies pumping out at the same time and in different venues the acoustic can change it quite a lot.. It's mostly the bass thats causing the problem but whatever i get has to be fairly good across a wide spectrum of low frequencies.. Id guess and say anything from 160-200hz and down... Ive tried emailing some places that sell vibration isolators and things im just waiting to hear back.
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Old May 4th, 2010, 01:42 AM   #22
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Yes, of course it's best not to have to use stabilization S/W, but at least if you can get into a range where it would work you'd be ahead of the game. I'm not surprised that it's dependent on where you are on the floor.

Did you try hand holding? If so how does it look compared to the tripod munted shots? In other words how effective are YOU as a vibration damper? I think if hand held footage is more stable (maybe normally jerky as hand held usually is, but not as prone to higher frequency vibration) then it would seem to prove that isolation and mass (YOU) will do the trick! Then it's just a matter of finding the right amount of isolation and mass needed. Mass does wonderful things in combatting vibration - it's why industrial machinery is purposfully made so heavy.
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Old May 4th, 2010, 01:58 AM   #23
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Thanks Jim.. I agree with what you are saying regarding the software aspect..

I have tried holding cameras in the past when its been a problem and it has worked ok, just the usual fatigue and shakes you would expect but no vibration from the PA.. This last time i filmed i needed to be fairly high up so i was standing on a stool and using a large tripod.. I didnt actually think to go hand held but im not sure how i would have gone anyway as i didnt have much room to balance on the stool and using a Z1 may have been a bit awkward in that scenario..

I just rang some places today and one person was very helpful.. he sold items for industrial machinery and things but seemed to understand sound a bit also.. he actually suggested trying squash balls under each corner of the wooden platform and maybe a few in the middle.. Then use a sandbag on top of the platform for weight.. Do you have any thoughts on how effective that might be ?

Im not sure how id secure squash balls thats the only thing.. originally i had thought of inner tube but something tells me sqush balls might work better ? (for a cheap attempt at a solution) ...
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Old May 4th, 2010, 02:28 AM   #24
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Hi Randy.............

Do you want to take this back to the "Camera Support" forum where it belongs, I'm finding it hard to keep up with the multiple threads going on here?

The "guys" have, as usual, come up with some great ideas and the idea of the squash balls isn't so stupid either (super glue, maybe?) but we're either in one Forum or another and it's getting a bit tedious, especially as this one has gone from mechanics to software to mechanics in two different Forums.

I'd like to think "the guys" would follow it, but am not so sure they're happy of the ground there (don't blame 'em).

Just a thought.


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Old May 4th, 2010, 02:43 AM   #25
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Good point Chris.

Just one thought re squash balls - they might make the platform roll around - maybe slightly inflated soccer balls would be better. I still think a 5 gallon can (with lid!) filled with water would be enough mass and you can carry it around empty.

Of course, a nice gyroscopic rig would be great but plywood and soccer balls and water would be cheap!

Anyhow, isolation and mass in one form or another should do it,
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Old May 4th, 2010, 12:00 PM   #26
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Actually an inner tube as you had mentioned might do the trick - but I'd use a bicycle inner tube and only inflate it about halfway - should be a perfect poor man's solution if you get enough mass above it.
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Old May 5th, 2010, 02:11 AM   #27
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Squash balls. That sounds painful.

You can keep them from rolling around by cementing them onto a PVC connector or a very short piece of pipe (try out different sizes), then cementing that to your tripod support. The plastic "collar" will stabilize the ball nicely.

Use an adhesive which works with elastic material to attach the ball to the PVC.

Roughen the surface of the ball with 80- or 60-grit sandpaper.

You might try Armaflex 520 adhesive. There's a guy who attaches pieces of old carpet to the bottom of his shoes for walking on the reef, and it supposedly holds nicely. You might be able to find this at Ace Hardware, etc.

Apply the cement, add a little weight to the plywood plate, and let it cure thoroughly overnight.

Other adhesives worth trying: Cyanoacrylates for leather and rubber. Five-minute epoxies that cure with some flexibility.

Keep in mind that the goal in adding weight is to increase inertia near the camera so that it takes more energy to impart motion to the camera and its optics. Suspending sand bags attached near the head of the tripod might be able to do this.

And you want to miminize any large surfaces that will be driven by acoustic impulses. A sheet of plywood will pick up more of that acoustic energy than a slimmer piece of wood. Making a triangle out of 2x4's would be less affected by loud sounds than a larger sheet of plywood.
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Old May 5th, 2010, 01:45 PM   #28
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I had thought of an egg holder upside down to place the squash balls in but i wasnt sure if constraining the balls ability to flex around its sides would negate its dampening ? When you say PVC pipe are you saying cut it off and use it so the pipe is still a full circle (similar to the egg holder) and placed vertically under the platform ? or are you saying cut it in half so you get half circle and attach it horizontally under the platform ?

I thought if i used the half circle concept i could cut it back fairly close and make it more like 1/3rd circle and make a small track of it to allow 2 balls side by side.. Then if i just glued the top part of the balls to the PVC it would probably still allow the sides to flex out fairly well..

Having said that im not sure the squash balls pressure is going to be tuned as well.. Im not a scientist but my intuition tells me lower air pressure will dampen low frequencies better, so i think the inner tube fairly flat might work better than squash balls with higher inflation.. Both those options are cheap though so I can experiment without it costing me too much.
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Old May 5th, 2010, 11:55 PM   #29
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Randy... Yes, just use a short length of PVC pipe to create a "cup" that will help keep the ball from rolling out of position. Diameter will probably be 1/3 of the diameter of the ball to help ensure the ball still remains flexible yet stabilized in place.
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