Long exposure on shakey ground

[carleton]

I'm trying to take a long exposure (3-5 mins) on a gantry that vibrates in a factory. The vibrations are varied and not at fixed intervals. Has anyone experience of photographing in these conditions? If I used large bags filled with foam or bubblewrap and stood the tripod on these, would it suppress the vibrations? Alternatively, if I suspended the camera from a large stepladder with bungie cords etc, might this work?
Please, does anyone have any suggestions?
Thanks.

[Liam:]

Have you tried using a wooden tripod? I have heard that they are able to absorb more vibrations than modern day ones.

[Richard Mc]

this may be out of your budget but you might want to look into using a gyro set-up.

http://www.ken-lab.com/

[IanG]

I photographed under similar conditions in a UK sugar beet factory (http://www.lostlabours.co.uk/sugar/index.htm) a few years ago, in the end I just used my tripod as normal. I made some trial shots in the beet extraction area which had by far the worst vibrations and was surprised how sharp the resulting images are.

It's more important to make sure your tripod is anchored well, so it doesn't jump with the vibrations.

Ian

[civich]

If the subject is fixed try multiple exposures during the vibration free periods until the accumulated time equals what you need. Has worked for me occasionally.

[eric black]

time will be your friend- the longer the exposure the more of a chance you have of the vibrations averaging out. I have done this with very slightly moving subjects and have come out with surprisingly sharp results. When faced with a situation like this, I do tend to make multiple exposures to up the odds of getting what I want.

[vinny]

http://blog.tompaiva.com/category/www-tompaiva-com/

[jp]

You might try putting a shot bag (of lead shot), or a bench rest shooting bag under each tripod leg. Shot bags are used to dampen hammer blows in metal work, and bench rest shooting bags are used to position sometimes heavy rifles for methodical but accurate target shooting.

[GPS]

...
If I used large bags filled with foam or bubblewrap and stood the tripod on these, would it suppress the vibrations?
...

It could suppress the vibrations but it would not help you, quite the contrary. You would introduce uncontrollable movements of the tripod on the bags themselves and the last things would be worse than the first ones...:(

[BetterSense]

If I used large bags filled with foam or bubblewrap and stood the tripod on these, would it suppress the vibrations?

Maybe, but it's hard to tell. It really depends on the frequency and amplitude of the vibrations, the compliance of the ground and tripod, and so on. You might be very successful in damping the vibrations, or you might make them even worse if you total system's "Q" just happened to be resonant with some of the vibration. Vibration damping can be very complicated. Usually the rule of thumb is just to add mass so to suppress the resonant frequency into ~Hz ranges but for long exposures even that might not help you.

[Stephane]

Break it down to 180 exposures of 1 second each... or 360 exp 1/2 s... Sinar copal self cocking shutter would help.
But I am not sure if shadow light will affect the film the same as continuous exposure.

[Brian C. Miller]

Has anyone tried Sorbothane (http://scientificsonline.com/product.asp?pn=3037000&cmss=sorbothane)?

[Nathan Potter]

BetterSense makes perfect sense and explains the problem well. I think he implies that it is impossible to predict a solution without an experiment. Such vibrations are a system problem involving all parts of the camera support system - even including the camera.

Possibly you should try using a vibration meter mounted securely to the camera to determine when existing vibration is at a minimum and for how long, then experiment with some vibration isolation devices as recommended above.

Applying very heavy weight to the tripod will reduce the period of vibration perhaps below the period of the support structure. Then additional advantage might be gained by using vibration absorbing material under the three legs. I've used multiple thin sheets of latex 0.020 inch thick maybe 20 to 50 pieces stacked on top of each other for pretty effective isolation.

Nate Potter, Austin TX.

[BetterSense]

http://www.sparkfun.com/commerce/product_info.php?products_id=9198

If you are a nerd like me, a few of these (placed orthogonally to each other of course) hooked up to a portable oscilliscope, sound card, or true RMS voltmeter would make a good vibration sensor.

Or a dish of water. Which should also help alert you to any approaching T-Rex's.

[IanG]

Vibration is relative and BetterSense isn't speaking =nonsense :D

In a factory vibration is transmitted to just about everything in an area, and it's all relative. An example in the sugar beet factory would be in the control room where the liquid in a cup of tea/coffee would be visible vibrating, particularly when heavy presses on the floor above kicked in. However the mug wasn't moving in relationship to the desk, computers walls etc.

Likewise in the beet extraction area where a huge slow churning drum weighing many tons causes severe vibrations everything is vibrating. Damping a camera against those vibrations and could have the opposite effect and cause greater unsharpness in the images.

When I made my first shots I was positioned on a steel walkway, I fully expected blurred images instead I found just the opposite good sharp negatives & prints the only movement is the rotation of the drum.

You need to do a test shot.

Ian

[lenser]

My first test would be with rubber pads like the kindergarten pads from Walmart, etc. or a cut up (at least 12"x12" pieces) pad like hair stylists stand on at their work stations. These are extremely cushioned and should dampen at least a good deal of the vibrations. Use these as large foot pads for a heavy tripod with rubber feet that are fully extended (the feet, not the legs) over the usual spikes. If you've got a wooden tripod, so much the better. You might also suspend a heavy shot bag C. 20 pounds) or water bag (C. 7.5 pounds, from a surgical supply co. for traction weights) from the underside of the tripod column to further anchor everything into the pads and to absorb vibrations sort of like the motions dampers on profession bows for archers.

Finally, either an air release or a very long cable release so it's not stiff like many short ones. Set your shutter, wait half a minute or so to let any vibrations from that action to die down and then make your shot. It's obvious, but worth stating anyway, do not move while the shutter is open unless you are on very solid base like concrete.

[sergiob]

Use a very big format, that way when you downsize the image, unsharpness will not be evident.

[GPS]

Use a very big format, that way when you downsize the image, unsharpness will not be evident.

That would only lead to the use of longer focal lengths and consequently even more pronounced vibration problems. :(

[Liam:]

If its in a factory can you not wait until everyone has gone home? Or is that a stupid question...

[Michael Rosenberg]

Bettersense, well does make sense. I have done photography and photomicrography when vibrations were present. Dampening the vibration frequency wave by using weight is your best bet. Put the tripod legs in buckets filled with sand (the cheapest and one of the best absorbers of vibration energy, and then tie the center columnof your tripod to a heavy weight. Do not let any weight swing off the center column as that will introduce vibration.

Mike

[Steve M Hostetter]

you say that the vibration is not constant.. I don't know why you couldn't cover the lens w/ cap while the vibration is happening and remove the lens cap when it settles down.

Do this as many times as you need to and remember to stop the clock in regards to exposure time while your lens cap is covering lens

[Steve M Hostetter]

^^^^I keep forgetting some of these lenses use shutters^^^^:D

[debanjan]

If feasible, have three buckets filled up with sand and use them as the base for your tripod legs -- many speaker stands are made with this principle to reduce the vibrations of the speaker itself and produce better sound..

[Harold_4074]

The comment by Bettersense is on the right track; all other things being equal, more mass means a lower resonance frequency. But the frequency is (roughly) proportional to the square root of the ratio of restoring force (the "stiffness of the spring") to mass. If the catwalk isn't noticeably swaying, the vibrations frequencies are probably in the tens of hertz or higher, and you can achieve a resonant frequency down around a hertz or less by using a large mass and soft spring.

This used to be done for analytical balances, optical equipment, and the like by putting a piece of plywood on three inner tubes (forklift or wheelbarrow tubes are conveniently sized) and then stacking bricks or bags of sand on top. With just enough air in the tubes to "float" the assembly and level it, whatever is on top will be isolated from upward-traveling vibration at frequencies much above the "bounce" frequency.

A word of caution: you mentioned a catwalk, and we are now talking about a fairly large load (your weight plus the isolation stand) that might be a bit much for the construction. But you can test it out on the ground to get an idea of whether or not it will work.