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-   -   Crazy though it sounds (https://www.dvinfo.net/forum/dolly-track-cable/115050-crazy-though-sounds.html)

Colin McDonald February 17th, 2008 11:15 AM

Crazy though it sounds
 
Has anyone had any experience of using railway tracks to run a dolly on?

What problems apart from the trains (there won't be any) would you anticipate?

I have a somewhat unusual shoot in the planning stage.

Andy Tejral February 17th, 2008 01:17 PM

Quote:

Originally Posted by Colin McDonald (Post 827883)
Has anyone had any experience of using railway tracks to run a dolly on?

What problems apart from the trains (there won't be any) would you anticipate?

Mainline, well mantained track would be perfect for a dolly. But they are going to have trains on them and the railway is going to be a little fussy about you working near let alone on them.

Branchline track is less well mantained and will not necessarily be smooth enough.

Abandoned track will likely NOT be suitable at all--depending on how long its been abandoned.

And one last thing: unless you KNOW the line is abandoned, expect a train at any time!

Onno Perdijk February 17th, 2008 01:18 PM

Quote:

Originally Posted by Colin McDonald (Post 827883)
Has anyone had any experience of using railway tracks to run a dolly on?

What problems apart from the trains (there won't be any) would you anticipate?

I have a somewhat unusual shoot in the planning stage.

I have done it a couple of times:

First Time we have taken a lorry from the railroadcompany: Bad choice, Iron wheels on iron tracks gives a bumpy ride on slow movements and long lenses... (rust)... We had to do some cleaning and sanding before it was a usable shot.

The second time I did some prerigging and made my own plywood-dolly with scateboardwheels. That worked very nice, beside the fact that we (in the filmbiz) have a less tolerance in trackwidth as the the railroadcompany has.. The distance fluctuaded within 4 cm.... so be aware with the figures you are measuring.

Our filmtrack joints are nearly perfect, the railroadtrack joint are useless: The gap in between sections can be an inch, some wood and tape will help you to get rid of it (put the tape crossway the gap, as you get what I mean??)

Good Luck

Onno Perdijk
Keygrip, amsterdam, Holland
www.solidgripsystems.eu

Andy Tejral February 17th, 2008 01:26 PM

Quote:

Originally Posted by Onno Perdijk (Post 827940)
The distance fluctuaded within 4 cm....

That would be the poorly maintained kind.

Something like the Chunnel, that would be perfect.

Colin McDonald February 17th, 2008 02:33 PM

Quote:

Originally Posted by Onno Perdijk (Post 827940)
I have done it a couple of times:

...Our filmtrack joints are nearly perfect, the railroadtrack joint are useless: The gap in between sections can be an inch, some wood and tape will help you to get rid of it (put the tape crossway the gap, as you get what I mean??)

Good Luck

Onno Perdijk
Keygrip, amsterdam, Holland
www.solidgripsystems.eu

Thanks - this is the kind of thing I needed.

These tracks are in a former depot, now used for another purpose altogether, so no need to worry about trains. The rails are set in concrete so they won't (I hope) be any more out of gauge than when they were in regular use for transport maintenance. The track is being used in a most unlikely way at the moment, but that will probably help if I get to use it.

I hope to be able to post some footage if and when the project comes to fruition but I can't say much more for now as there are a lot of permissions still to be negotiated.

Any further thoughts welcome. One thing - I am not concerned about noise from the track and wheels, but vibration would be an issue. The lighting will not be entirely under my control either.

Onno Perdijk February 17th, 2008 03:25 PM

the 4 cm (in)tolerance was in the curved situations btw... just to be aware of when you are making your own dolly!

I do not want to be to smart but: sound is a wave.. and a wave is a vibration.... :-0) So if there is a sound, there will be a vibration in the camera (noticeable or not?)

Onno

Colin McDonald February 17th, 2008 06:30 PM

Quote:

Originally Posted by Onno Perdijk (Post 828000)
the 4 cm (in)tolerance was in the curved situations btw... just to be aware of when you are making your own dolly!

I do not want to be to smart but: sound is a wave.. and a wave is a vibration.... :-0) So if there is a sound, there will be a vibration in the camera (noticeable or not?)

Onno

The track is all on a straight.

Sound and vibration - interesting - never really thought about this before. Sound waves are with us always, but the actual energy imparted to an object set in vibration by them is normally fairly miniscule. Sound waves do not usually vibrate cameras to the extent that there are problems with focus or resolution (but be careful with trombone pedal notes close up, and filming beside speaker columns to name but two known problems). The frequencies I would expect to be most likely to cause problems would be those at the bottom end, near slower shutter speeds. Unless you have encountered an operatic soprano who can shatter lenses I am not aware of mid to high frequency sound waves being an issue on vision.

I did however find my camera and tripod setup had a resonant frequency which could be triggered by one particular speed of zoom.
http://www.dvinfo.net/conf/showpost....5&postcount=22

Vibration through direct mechanical contact - camera mountings, floors, towers, on vehicles etc. on the other hand is a constant pain. There are buildings where vibration from trains, traffic etc - even the ocean - makes it hard to film and often this can't be heard, just felt (and seen).

I do not expect to filter out all noise from using railway tracks for dollying inside a building (actually I don't even want to in this case) but I hope not to have wobbles on the camera.

Cole McDonald February 18th, 2008 05:47 PM

The cops'll probably kick you off of them as well...so keep that in mind when scheduling shoots.

Alessandro Garabaghi February 19th, 2008 09:56 AM

Sound is very much a vibration, trust me if I pull up to your scenes with my truck on full blast, it will most likely vibrate all your cameras and maybe even knock over a tripod or two =D.....

Colin McDonald February 24th, 2008 08:58 AM

Suggestions for insulating layer
 
The place is now an art exhibition area, so no trains or cops (thank you Cole!), but the whole project is still awaiting permission to film in this building.

I checked the track carefully for joints yesterday and found the likely trouble spots. There are several small 4 wheeled trolleys already in the place and they run fairly smoothly by railway standards (though not to camera dolly standards).

I am thinking of using one of the trolleys, which are about waist high, with the tripod on minimum height sitting on it. Some kind of vibration insulating layer will be needed. It will have to be absorbent enough to kill most of the vibration but not so flexible as to introduce new lower frequency oscillations.

I'm going to keep the dolly shots as wide as possible so any remaining vibration is not so noticeable.

I thought of some sort of foam or layers of heavy cloth. Any suggestions?


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