Help stabilising a tripod
 

I film at loud concerts and sometimes we have problems with vibration off the floor through the tripod.. It can be really hit and miss and i hate deciding where to put a camera based around potential for vibration rather than the best angle for the shot..

Does anyone know a solid way of tackling the problem ? Other than going hand held ? Sometimes in the past i have used a monopod and if the floor is vibrating i just put the pod on my foot and raise my toe slightly and it stops it.. Not the solution i want obviously but it has gotten me out of a hole at the last minute.. In that instance i guess my body is absorbing the vibrations but its made me wonder how and why vibration becomes a problem and how to reliably solve it..

There are often situations where the floor is a bit flimsy and the conceert is just too loud, but those are things we cant change so i need to find a way around it without compromising the angles..

Does anyone know if its better to try and place weight on the tripod in order to make it firmer or would it be better to allow more freedom somehow ? If the floor isnt solid to start with and i put more weight on it im wondering if that will just intensify the vibratipon through the legs ? Sound travels through something solid better than it does loose i thought..

Also a steadicam isnt an option really, we need to be elevated really high and steadicam isnt practical without a very firm platform to stand on and we dont have that facility.. It needs to be tripod..

Anyone have any ideas ?

Hi Randy.............
 

We meet again!

You pretty well had it nailed in your question, but missed it, so I'll fill in the missing letters.

In order to keep that tripod from moving, you need two things, a decent mass to make it as imoveable as possible AND something between it and what IS moving that needs to move in preference to the tripod etc.

My suggestion (based on a whole 3 minutes thinking) is to plonk the tripod in question (unknown) onto a sheet of 3/8" plywood and mark out a circle that will encompass all three legs at the maximum spread you're ever likely to use it at such a venue.

Find the radius and mark it clearly, then cut it out of the sheet.

Now, you have a camera platform.

Check your tripod type and find out whether you can buy tethered boots that can be screwed to a solid surface - like these:

tripods, heads, monopods, light stands, camera supports, lighting supports, professional tripod 565 - RUBBER SHOES FOR SPIKED FEET

If so, buy a set and fit them to the top of the platform.

Then, here it gets experimental.

You need to find some solid foam (if that isn't a complete contradiction .........) that can be glued to the underside of the platform and some weights that can be placed on top of said platform.

If the deformation charachteristics of the foam can be matched to the weight/ inertia of the platform weights and camera weight, you're home free, or at least a heap better off than you were.

I could bang on about this but I'm sure you've picked up the drift by now.

I can't see any other way to isolate the tripod/ camera from a vibrating floor, apart from a Steadycam which you've already ruled out.

Give it some thought.


CS

Chris.. I never thought of creating a base under the legs and its a great idea.. This would allow the entire underside of the base to be covered with absorbing material and makes it easier to experient.

For the material underneath the base, i guess some sort of foam is the obvious choice but i also just thought maybe an inflated tyre tube ? Since that would allow you to regulate the air pressure , it might be good to help work out what "settings" worked best ? But maybe air in that situation wouldnt work too well either ? Im not sure..

There could even be some other material im not aware of out there, having the base definately makes it easier to work with..

I will try calling some foam places tommorow as a first start and see what people say.. If i do this i will use some material stapled to the edge all the way around the platform so that it hangs down a few centimeters to hide whatever i have underneath it.. Then i could just use some sandbags on top for extra weight also..

Well, thank you Randy...........
 

I may be old(er) but I'm not a complete cretin, just yet.

I'm really intrigued as to how this goes, 'cos if you can get this sussed, there may be a market for it elsewhere, heck, you're not the only one in this situation.

May just make your fortune, who knows.

Send me a commision cheque sometime if it takes off.


CS

I just found something that looks promising in the war against vibration...

AAC Alpha Gel Silicone Thermal Gel Sheets, Pads Mounts

The silicone gel mounts look good.. I could bolt them to the underside of the platform and then put normal rubber feet underneath that which could work.

Way to go , kid...........
 

way to go...........

suck it and see, keep us posted.

However, remember, the path to true love........................


CS

I do think its a fairly common problem which doesnt seem to be addressed by any video companies.. maybe its because its difficult to overcome properly ? Im not the entrepaneur type but its possibly an oppourtunity there..

It would be a great project (to make a marketable product), if you worked a day job somewhere that dealt with the science of vibration or even somewhere like the store i linked which made related products so you could test your inventions as you go without needing to pay so heavily for trial and error.

Some other stuff on that site looks really promising but it gets expensive.. Something tells me this would really do the trick.

Air Springs

I emailed them anyway so i'll see what they say.. If it takes me a while to get something together i'll still make sure to get back to you with my results.

Ah, I've seen them before............
 

They, or something very similar, is what sits under just about every train carriage in the UK that was manufactured after 1990 or thereabouts, and thinking about it, some buses as well.

They work great, but, of course, the loads have to be worked out.

Keep us posted, Randy, I think this is very promising.


CS

Thinking a bit more......
 

You're idea of an inner tube doesn't sound all that silly, apart from one small problem, the wobble effect, which I think would drive you to distraction.

Keep thinking there Randy, you'll make it fly yet!


CS

thanks mate.. i'll see what that place recommends.. im confident they will understand the nature of the problem.. in the meantime i'll look to get the wooden platform cutout and i might even see if i can find an inner tube to experiment on the cheap.. that would give me an idea..

Randy,


I have two thoughts:

1. quality carpet sublayment ( you can get pertty firm stuff if you look about.

2. At cosco or wall mart there are firm foam matts for kids to play on and they are inter locking,,

these or a combination there of would likly do the job!!!


I have a shoot in two weeks, I think I might try them on. they would also be good for slick floors!! At least if the camera is stationary.

dale

Try turning on your steadyshot. In this instance it might be more help than hindrance on a tripod.

I cut some 6-in squares from a camping mat (closed cell foam - I think this is what Chris meant by solid foam) and taped a double-thickness to each tripod foot. It certainly helped, although my problem was a wooden floor with people dancing, and probably the music not quite so loud as your concerts.

before speaker isolation was commercially available, we used to use 2" thick neoprene rubber. It's REALLY heavy and damped out any vibration thrown at it. Typically we'd use four 3"x3" squares under a speaker. I'd imagine you could put his stuff under a tripod with great results. I'll see if I can find a source. It's been a lot of years!

You could try several styles of blister sheet used for packaging, you know the stuff they give little old ladies to pop in nursing homes.

This has both the air cells and a good spread of them. So there hopefully should not be movement of the shot by the operator walking around on the plywood sheet if you make it larger. By the way, I would make that thick to avoid compliance in the board allowing the tripod to move or local bends popping the cells during the concert. You don't want people diving for cover thinking the local gangbangers are having at it.

You could also try strings of the larger sausage cells used for heavy items in crates but I think you will find these too compliant and hard to manage, needing two plywood sheets and glue to hold the cells in place. The strings would have to be laid out in concentric boxes otherwise they will tend to roll in one direction.

These would be the closest you will get to three or four concentric patterns of small to medium kiddybike cycle tubes for corner airbags which would also be a bit floaty.

To stiffen cycle tubes, fill them with water. What little air remains in them and their ability to stretch would do the rest

Thanks for all the great suggestions.. I still havent started to work on anything yet but i will report back when i do.. I have some things to film in a short while so i will need it sorted in the near future.

The problem with loud sounds is not easily overcome. Adding a sheet of wood into the mix is adding another microphonic element into the mix. The drum beats will be picked up and the sheet will vibrate in sympathy. This is the exact wrong direction to go. (Sorry Chris)

Chris is right in that adding mass and decoupling is needed. One way to do this is to use a foot level spreader or dolly. The three points can be isolated from the floor by just sand bags in some cases, by triangles of wood with three tennis balls glued on and the tennis balls partially cut off, or with small soft rubber things. I am being specifically vague here because each setup and each venue has their own requirements as to what is the best decoupling compliance.

Adding mass to the tripod near the top can help detune the tripod from resonating at the specific frequencies that are upsetting the image. Sometimes putting a sand bag one just one leg can fix all the problems in vibrations. As a general rule, try not to have all the legs have the same mass on them so that they all don't resonate together at the same frequency. Sand bags are your friends.

And one last thing; most image stabilization systems do not like vibration and can make the image look even worse. Make sure that any stabilization is turned off in these kind of environments.

In summary, detune similar parts so they don't have the same resonant frequency, image stabilization off (but it shouldn't be on when using a tripod anyway), do not add sound receiving materials into the mix such as sheets of anything, and decouple the legs from the vibration using any method that works for the situation. This last point means carrying around many different things in your concert kit bag.

Well, welcome back, Les.............
 

Glad to see you survived the earthquake carnage unscathed.

Back to the chase.

When I was considering the problems faced in the environment that Randy shoots in, I was minded of those aerial video clips from Vietnam, showing the results of high level bombing on jungle areas in high humidities.

Those as can hark back that far will remember the rapidly expanding doghnuts of high pressure "cloud" created by the blast wave travelling at the speed of sound in air (the ground blast travelling considerably faster and clearly visible in some shots.

Mapped to Randy's circumstances, if you consider those big speaker banks as "ground zero", then the first thing the pressure wave is going to do is push that floating wooden floor down vertically, then suck it back up again, creating a vertical pressure wave radiating out from said "ground zero", travelling at some colossal speed, as it is radiating through a (more or less) solid.

This means that to protect the camera support you need to isolate it from that vertical wave. I gave a lot of thought as to how to acheive this isolation and every scenario just led me to the same dead end due to the sheer bulk of individual shock absorbers for each leg and the sandbags required to achieve the necessary inertia.

Being mindfull that sandbags need real estate and must not at any point touch the floor, else they will "short circuit" the isolation, I concluded a platform was really the only way to go.

However...............

Going back to "ground zero" for a moment, we need to look at the second thing that is going to happen with that shock wave. This is, of course, a spherical pressure wave travelling at the speed of sound (much slower than the floor shock wave) which is going to rattle the teeth of anything with a plane cross section parallel to the line of travel.

Compared to the tripod legs, head and camera, the platform has a minute plane cross section in the direction of the shock wave travel, AND, being suspended at some distance above the floor will allow the shock wave to travel both over and under it, cancelling it's effects out to a great extent. There will be some minor attempt to move the platform back and forth but there should be enough inertia imparted by the necessary sandbags to keep that to a minimum.

Thus, although the platform is not ideal, it appears to be the lesser of all the available evils.

(Sorry Les......:)

Of course, this leaves us with the major problem of that airborn pressure wave acting on the above mentioned legs, head and camera. As you have highlighted, Les, this is a real can of worms, and whilst all your suggestions are valid, I can see no perfect solution but to have some sort of rigid, curved barrier which physically prevents the pressure wave from impinging on the exposed elements.

How you contrive such a monster, move and position it etc etc is proving a major stumbling block, tho' as anyone who has sought temporary refuge in a disco from the speaker towers by cowering behind a concrete support pillar can attest, it works.

Nice to see you back, Les!


CS

Thanks Chris!

One has to consider that there isn't a simple single spherical pressure wave expanding from a point. In any real concert environment there are multiple sources and multiple paths for them to be reflected. If the tripod is on a floor that isn't 1 meter of concrete the floor itself can re-radiate stored sound energy. There are many variables to consider that can affect a sheet of plywood sitting a few centimeters from the ground.

The reason I am so emphatic about this is because I ran into this situation and solved it.

The particular situation was one where I was AD on a music video shoot and the camerman had brought along his homemade (but well made) dolly and track system. It tracked smoothly but as soon as the drummer started to kick away at his bass drum the image went wild. The cameraman and the director had no idea what was going on and asked me to look. The dolly was a sheet of plywood straddling two runs of rigid plastic tubing on roller skate wheels. The tripod legs had been placed in sockets that placed the legs at two corners over the wheels, and one over the middle of the board. The only thing that tamed this problem for them while they needed the tracking shot was to sand bag the centre of the board, place a sandbag on the middle of the board leg, and hang a weight from the middle spreader. The floor that all this rolled on was a thick poured concrete base. The camera behaved properly hand held, and on a tripod NOT on the plywood sheet.

As I said, there is no right solution that works for every situation. Each vibration problem must be approached with imagination and the willingness to try whatever works for that one time. Floors will be different, the acoustics and speakers will be different, the camera might be different, and the height of the tripod can change things too.

I did not say what I did in my previous post as a theory, it is from practical experience.

One last thing. A sheet of wood a few centimeters above the ground does not provide a symmetrical area top and bottom to a pressure wave, and it also depends on the wavelength of the sound involved.

Good thread
 

I just ran into this tonite at a concert, the base on the drums was so loud, my back camera was bouncing. I think I'm going to get a couple of those foam puzzle pieces and see if I can do some testing. Maybe if I cut sections off, tape them together and put them under the legs............. is there anything gaff tape can't do?