I seem to remember reading about something that goes between the dolly and the camera head that removes small bumps. The article said that it allowed them to do without dolly track in a lot (but not all) situations. It was relatively small in size. Does this ring a bell with anybody?
Marty Mullin writes:
>>I seem to remember reading about something that goes between the dolly and the camera head >>that removes small bumps. The article said that it allowed them to do without dolly track in a lot (but >>not all) situations.
Chapman Vibration Isolator -- there are a couple of versions/sizes.
IA 600 DP
Chapman make a device that goes between the head and Mitchell fitting on the dolly that has steel bars that go in two axis and then there is a plate with linear ball bearings that slide on these bars. These bars have coil compression springs that push on this plate. The bars go horizontal and to my surprise they take the bumps from low frequency vibrations out pretty good. The camera and the head slide left to right and front to back. Makes no sense to me as I would expect the bars to be vertical. I have seen it work.
Clairmont Camera makes vibration damper but this is more for things like a car going over a wash board road as these are high frequency vibrations.
Denny Clairmont wrote:
>>Chapman make a device that goes between the head and Mitchell fitting on the dolly that has steel >>bars that go in two axis and then there is a plate with linear ball bearings that slide on these bars.
I think the folks at Chapman were thinking the same thing. At NAB this year they introduced a vibration isolator that operates vertically. It looks a little like a Steadicam on steroids.
IA 600 DP
Hmmm... the vertical travel parallelogram unit that Chapman has for damping vertical movement has actually been around for a while. I've played with it a few times and spec'ed it for two or three jobs which cancelled. Clever design with spring counterbalance and air shocks with both compression and rebound damping adjustment, which makes it tuneable for a variety of nose loads... I think it is primarily meant for use with remote heads on tracking vehicles, though, like many devices, I think it could be adapted to a number of specialized uses. I will point out that the horizontal spring-loaded linear bearing device should be relatively operable with either a geared head or a fluid head, since it is rotationally rigid, whereas a rig with vertical springs might be a bit harder to use with a fluid head without a bit of sponge or backlash in the tilt axis unless you operate with two handles... one rear pan handle as usual and one forward pan handle and lower than normal tilt drag.
I admit that I have never used that horiz device as a stabilizer... but it is a great thing to stick on a dolly if you want to add a bit of camera shake for dramatic effect... operator operates as normally and someone else grabs the body of the pan head and shakes it against the tension of the springs.... we used it that way on something once.
LA based VFX DP/supervisor
The problem I'm trying to overcome is how to dolly with out track on a rubber carpet that's "covered with low, small bumps about the size of a nickel." Would that be low or high frequency vibration?
>>The problem I'm trying to overcome is how to dolly with out track on a rubber carpet that's "covered >>with low, small bumps about the size of a nickel." Would that be low or high frequency vibration?
It depends on how fast you are moving... but seriously, that would be low frequency vibration. This is a tough one, because it all depends on how far apart they are and the diameter of the dolly wheels as to whether or not they will bounce you up and down a lot. Go with either soft wheels or pneumatic wheels if the options exist where you are getting your dolly... and you might even consider a dolly with large diameter wheels like the old Fisher 9 which might bridge between the dots without bumping.
For that matter, if you are definitely not on track, (or going to channels when on track) get a dolly with full width wheels instead of wheels that are cut out for round track as the greater width might help... If you can get a piece of the floor and take it to Chapman or Fisher and roll one corner of a dolly over it, you will know immediately what you are in for.
You are going to HATE this suggestion, but an ancient Moviola dolly with a little air out of the pneumatic tires will work just fine... but the dolly is a pig.
LA based VFX
Chapman's have a few variations on the VI (Vibration Isolator) as mentioned here; the original VI is the horizontal unit that everyone seems to be aware of.
There are 3 different Vertical Super VI's, the Original, the Mini and the Mini Micro. The original was designed for use on the Lenny Arms with the Chapman Gyro-stabilised head.
The Mini was designed for more compact applications and comes standard with the gimbal (underslung adapter) for mounting remote heads it can be utilised overslung with the addition of a 3" Riser and a horizontal VI (the traditional VI).
The Micro Mini was designed specifically for Dolly applications as per your request; it comes standard with the traditional VI and cannot be underslung. This would best suit your needs.
All of the above can be tweaked as Mark mentioned to allow for different camera loads (read weight) and different shock response, in an ideal set up the VI should always return to 0 i.e. a point of neutral balance, Chapman's or one of their vendors should be able to demonstrate this on collection.
Further, to this discussion as Mark mentioned you should look to using a very stable dolly with Pneumatic Tyres (Soft Compounds will not suffice, they are only really beneficial on 'ballroom' type surfaces), the Pneumaticscan be deflated to better accommodate the surface, my suggestion would be to use a Hustler IV also from Chapman's with a set of Pneumatics. The Hustler IV has round, crab and conventional steering to accommodate your environment, and it has 8 well sized pneumatic tyres which with a little deflation and a Micro Mini Super VI should hopefully accommodate your request, alternatively use a slider, a skater mini or lay track ;).
More information :http://www.chapman-leonard.com/
Under Products you will find a heading: VIBRATION STABILIZING MOUNTS.
DISCLAIMER: ONE8SIX are a Chapman Leonard Representative.
Hope this helps,
Dean Slotar | One8Six Cape Town
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