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Indie filmmaker, need advice on glide tracks??


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#1 Greg Banfield

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Posted 17 November 2011 - 02:46 PM

I'm a horror writer hoping to make the step to director.
I have a 7D, lenses, lights, Manfrotto tripod, Sony Vegas, and a shed load of scripts.
All I need now is camera movement equpment and I am ready.
I am looking into glide tracks for that gorgeous sideways establishing mid-shot.
Anyway, question is this..
These tracks can cost an arm and a leg for a mere metre of smooth movement. But.. what makes it slow?
Question sounds stupid, but I understand a smooth movement with no jerks or changes in direction.
But as far as the slowness goes, is it down to cameraman skill or does a professional glide track give 'resistance' to maintain a steady speed?
I've never had or even seen one of these things up close so I have never got to play with one.
http://www.glidetrac...detrack-sd.html
It's hard to find a shop in the UK with these kind of things in-store.
So to summarise, do they resist against irratic pressure fluctuations or are they simply a rail and carraige and it's down to you to be smooth?
If it's the latter, I can engineer something like that in my sleep.
Anyway thanks for your time.

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#2 Phil Rhodes

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Posted 17 November 2011 - 04:58 PM

I'm sure you've seen pictures of high end track and dolly setups - they're simply very, very heavy, and it's very hard to make something that heavy move in a chaotic manner. Physics sees to it that the thing tends to keep going in a straight line. This is why small, lightweight dollies can sometimes give less than stellar results - piling on a couple of spare wheels and a bunch of sandbags tends to improve things. Until the thing breaks, of course.

Beyond that, it comes down to careful tracklaying, well-maintained equipment and skilful pushing. Moves that need to go on for more than one length of track rely on the sections of track being properly mated together and supported, and laid in a straight line. This usually means knocking wedges in underneath the track to support it and keep it level. If it isn't properly supported, even if the track is level, it can flex and cause the camera to roll around drunkenly at various points in the move. Grips commonly polish track with furniture polish, both to let the wheels glide (particularly around corners where they might not want to actually roll) and to ensure absolute cleanliness. The surface of track and the condition of the track wheels is something that often doesn't get the attention it deserves. Needless to say all of these things are difficult with tatty plastic track and a dolly that's been repeatedly rolled over a gritty concrete parking lot.

There is usually no resistance beyond just the weight of the dolly, meaning it's just as hard to stop as it is to get going, especially if there's an operator and focus puller aboard.

Like most things involving precision, it's the culmination of a lot of things not being wrong all at once.

PS you can rent mine if you like!
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#3 Stuart Brereton

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Posted 17 November 2011 - 11:43 PM

It's the weight which gives you your inertia and hence the slow steady movement, as Phil says. Bearing mounted Sliders tend to be very expensive. So called 'Skateboard' dollies are generally much cheaper and more flexible, although the build quality varies, and they don't have the inertial drag. Most people tend to drag their fingers along the slider or rail as they push them

I have a Dana dolly which is very solidly build, well thought out, runs on 1 1/4" pipe (32mm for those on the metric system) and is good for cameras up to 100lbs with a mitchell (moy) base built into it as well as adaptors for 75mm, 100mm and 150mm bowl fittings.

They recommend schedule 80 Aluminum pipe for use, but I've had great results with 1 1/4" steel electrical conduit which I can get at Home Depot for $9 for 10ft. I'm guessing B&Q would have something similar. The Dolly is about $600, so £400 plus tax and shipping.
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#4 alex payne

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Posted 29 January 2012 - 10:48 AM

it's distance. the farther the camera from the subject, the wider the lens, the slower the movement will appear.
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