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Sled length


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#1 Philip J. Martinez SOC

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Posted 12 April 2007 - 08:44 PM

Just a question.

It seems that Steadicam brand sleds are 28?-71?

Where the other brands are 17?-28?

Why is this?
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#2 Michael Stumpf

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Posted 13 April 2007 - 11:50 AM

Just a question.

It seems that Steadicam brand sleds are 28?-71?

Where the other brands are 17?-28?

Why is this?



Because of weight distribution.
The heavier the top stage and upper junction box is the longer post you are going to need to counter balance.
As well as, the lighter the lower part of the sled is the longer the post is going to be needed.
Steadicam brand has electronics in the upper stage and motors for their tilting and such.
That adds weight and therefore requires longer posts to balance.
Many of the Steadicam brand also uses the single battery system as well as lighter LCD monitors on the lower section of the sled.

Combine those two aspects together (heavier top section AND lighter lower section) and you have the need for a long post to balance the cameras you put on the sled.

This is at least part (and maybe most) of the reason.
Oh, and in some cases you can request the length post you want too.
The 28-71 inch post you are referring too sounds like "super posts" to me and extend out far for ultra low and ultra high
mod operating.
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#3 Jerry Holway

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Posted 13 April 2007 - 05:30 PM

Philip-

The difference in post lengths also has a quite a bit to do with how the sleds are made; sometimes the post is shorter (17-28") but the sled base may add 10 inches more than that to the overall sled length... so you are not comparing apples to apples when one copmpares the "post length" between rigs.

The Ultra and Ultra 2 sleds' posts go right to the bottom of the sled, so the minimum sled length may appear to be longer than others. In the shortest modes, the Ultra sled is the same length as the Master Series sled was (which had a much shorter and quite limiting post). If one just compared post lengths, you would think the Master Series was 13 inches or so shorter than the Ultra.

The 28-72" post length does indicate an integral superpost, but the longer length has almost nothing to do with a heavier top stage. It's less than a pound up there; lens changes often shift the weight more than that, let alone different cameras.

An integral superpost gives the operator flexibility in placing the lens relative to the gimbal, especially if the camera is lighter. Heavier cameras restrict this feature, but one can at least balance anything easily, without adding weights to the bottom (anything they've thrown at me, anyway!).

Hope this clarifies.

Jerry
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#4 Jerry Holway

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Posted 14 April 2007 - 09:29 AM

Jerry- (I'm replying to myself!)

Michael is right that the original Ultra may longer in the minimum configuration than some other sleds, and will end up a bit longer (1"?) than some other big sleds (all other things being equal) with most camera packages.

As Michael said, the weight of the battery and the weight of the monitor both dropped as thye changed from the 5" Green Screen to LCD (-3 pounds) and better NiCads (as did all NiCads). The latter had only a very minor effect on sled length, and the monitor weight change was mitigated somewhat by being able to drop the monitor much lower than before (and further out for increased inertia, more than before).

As a result of exactly these concerns (and some other desires), the Ultra 2 has two monitor mounts to get the monitor extremely low, and with two batteries, the battery pack is about the same weight as the original NiCad. The new battery pack can also rotate downward, keeping the posts shorter, although the rig length grows...

The length of the Ultra post (28-71") was chosen to get the sled to the "magical" six foot length and to a reasonable minimum length, with the maximum flexibility of gimbal position, and the bigger diameter posts downwards for maximum stiffness. All these concerns (and one or two others!) were taken into account.

The rotating battery mount of the Ultra2 permits an even longer possible sled...

Jerry
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#5 Philip J. Martinez SOC

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Posted 14 April 2007 - 05:09 PM

Thanks for the reply's
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