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Digital levels

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#1 Ed Moore

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Posted 15 April 2008 - 09:33 AM

Question for those you with the RVBM sleds (requires visit to bank manager) - my archer has a bubble level which is obviously not very useful when the sled is accelerating or changing direction rapidly. As my levels are most often screwed by fast cornering, this is annoying.

The cure for my levels is more practice, but I was wondering whether the digital variety of level, with the on-screen display, works in a different manner and therefore provides useful information with regards to level 100% of the time.

It's my understanding that levels of any sort are seen as perhaps something of a crutch for the very experienced operators, so I'm not suggesting that having a digital level is some sort of magic sauce, just curious about the technology involved.


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#2 Matt Petrosky

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Posted 15 April 2008 - 06:59 PM

The digital levels are not inertia-proof, but I think they handle it a bit better in terms of a faster recovery to an accurate read-out. Also the sensor itself is usually mounted very close to the center of the center post which serves two purposes. One, it can provide a more accurate, less-biased reading (assuming proper zero setting) because it is closer to the center point of the gimbal (which would be the ideal placement for a level sensor). And two, because the sensor is not way out on the monitor like a bubble level it takes a faster pan to upset it then the equivalent if the sensor was placed on the monitor.

Not sure if this explanation is clear, maybe Eric or someone can chime in. Also to clarify that the digital levels for steadicam are not technically artificial horizons (gyro horizon), like in aircraft, which are more tolerant of inertial forces.

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#3 Jerry Holway

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Posted 20 April 2008 - 12:33 PM

All the simple "level" indicators on our sleds (either bubbles or "digital/electronic") measure acceleration.

What we call "level" is simply the long term acceleration of gravity, and therefore we can't easily separate long term from short term. Relatively simple level systems like the one in the Master Series through the Ultra2 are more useful than a physical bubble because they can electronically ignore signals that can't be generated by the sled changing its angle (the sled can't change angle that fast, so it must be acceleration of the sled, so don't display that.) It can also ignore signals beyond a given number of degrees (say +/- 5ยบ) because we can easily tell if we are that off level, therefore the recovery time to long term acceleration (level) is faster.

More complicated systems use additional, different sensors for rotation and complicated software to try to keep track of where it's been and what each sensor is saying... it's guided missile stuff, and it can get confused, takes time to boot up, etc. The Alien uses this sort of technology, as does some of the big tripod mounted gyro heads.

All these simple level indicators are most useful when still, or moving at a constant speed straight ahead or backwards.

Use of an electronically fast (or bubble) level while tracking straight forward will also tell you if you are keeping to the straight path and flying well or over-managing the sled.

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#4 Ed Moore

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Posted 21 April 2008 - 05:32 AM

Thanks gents.
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