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Shackiness when running


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#1 Lohengrin Zapiain

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Posted 16 January 2007 - 04:00 PM

I have been having problems when doing running shots or fast phased shots with my Ultra. There is some kind of vibration on the image once I reach certain speed and then it disappears when I slow down. It looks like going on a bumpy road or like the vibration you would get if you ran holding a piece of paper by two of the edges and let the wind hit it.

I don't notice the vibration on my monitor but it shows on rushes.

Incidentally I had had this problem ONLY when I was using SR Advanced from Panavision and never with another camera. I search the forum but I couldn?t get any info.

Have any of you had the same problem?

Thanks and have a great 2007 filled with loots of work and money

Cheers
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#2 Afton Grant

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Posted 16 January 2007 - 04:26 PM

Hey Lohengrin,

It sounds like there is something that is not as secure as it should be and therefore creating vibrations when you run. This could be anywhere on your sled or camera. Even something slightly loose way down at your batteries will travel up through the post and into the image. Take some time and go through your rig piece by piece making sure that anything that can be tightened, is.

Even if your sled is completely buckled down, sometimes a lens will not mount completely snug. This happens more often as the physical length of the lens and its attachments grows. For example, I've found when shooting HD with a Pro35 adapter, lens, mattebox, and eyebrows, chances are good there will be some play in the lens. This is bad for vibrations and also for your focus motors.

Perhaps I can solicit some suggestions from the rest of the forum about what to do with "playful" lenses.

Best regards,
Afton
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#3 Lukas Franz

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Posted 17 January 2007 - 01:33 AM

Hi guys,

I had a similar problem once with a JVC HD101 and a PS lens adapter. And the problem has showed only as soon I was running with the rig. Luckely we had no video transmitter and the director watched the footage right after the shot. I didn't recognised the shakiness while shooting.

I didn't find out the problem on set and after the shooting we had to bring back the cam and the adapter.

Greets. Lukas
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#4 WillArnot

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Posted 17 January 2007 - 02:44 AM

Guys,

This speaks to an unfortunate problem that has haunted Steadicam for a long time. Now that you are aware of it, you will probably see it in alot more shots if you look for it. I'm not talking about your work in particular. I see it in alot of TV shows on fast walk and talks where I know the operator is hustling and not able to walk as smoothly as he might do otherwise. Watch the edges of the frame, you will probably start to see similar hi frequency vibrations that are not consistent. They come and go according to the physical energy the operator is producing.

Lohengrin, the vibrations you describe are high frequency and almost certainly related to the rigidity in the top stage. I know you say this has only happened w/ the SR but have you run with lots of other cameras? Have you really been looking for said vibrations? Have you done a long walk and talk on a 75mm and looked for it? Not that we often do walk and talks on a 75mm, but if it is there on a 75 mm, it's there on a 35mm.

Lack of rigidity in the top stage and base plate is an issue that many manufacturers have a hard time admitting to and will often simply deny. The easiest way to test is thus: The old 'Squeeze' test - with your baseplate mounted firmly in your top stage (no camera needed) and sticking out 2 inches or so in front, squeeze down on the end of the plate and see if there is any flex in the plate or top stage. Squeeze hard and be honest.

In the past I have used little wedges jammed in under the plate to try and stiffen this flex. This is a factor of several design flaws that I won't go into too deeply. It is fairly logical. Some 35mm set ups I fly can get up to 30 inches long from matt box to mag, and I've had HiDef cameras with zoom lens that were 39 inches long. That's almost 4 feet. Ridiculous but true and points to an exaggerated but realistic scenario.

What is the surface area that is being clamped by your top stage? If the ENTIRE top stage is truly clamping down, at best you have 3 x 5 inches engaged. It is easy to see how much mass is sticking way out in front and behind, and where the hi frequency resonation can come from. The length and mass of the camera exert far greater force on the plate than the squeeze test. If the plate flexes AND you have flex in the top stage the vibration effect is obviously compounded.

If you look further into this matter you will begin to find out why so many people now use Greg Bubb's XCS fat plate. It is the only baseplate that has ZERO flex. That is partly because it is a box structure and not a flat plate structure. I am not sure if it fits in the Ultra, I think it does, but this would certainly help.

Secondly, obviously the design and structure of the top stage is paramount as well. This is why PRO came out with the Donkey Box 3 and why Tiffen put a completely re-designed top stage on the Ultra 2.

Rigidity is crucial to me. Nothing compares to the rigidity of the XCS topstage that has no bearings in it to introduce flex. I did a 200 yard hard mount shot on a 150mm carrying a medium two shot at 50 ft away, and it looked f*%#*ing incredible. 3 gyros. There is no other sled that is as rigid as the XCS 2" post and top stage.

Once you start getting really into this, look at the diameter of the post where it meets the top stage. For all the integrated 4 stage posts, that diameter is smaller than the diameter of the post that the gimbal is on. While I understand why this has to be for a 4 stage post, I hate the idea that at the place where you need the best connection possible, why one would shrink the footprint and attach with a smaller base. This is why I much prefer to carry less weight in a 2 stage post and have a separate super post for long work. By having a 2 stage post, the diameter at the top of my post actually increases (shock, horror!) from 2 inches to 2.5 inches and almost 3 inches in diameter by nature of how the bottom of the top stage is constructed.

All these variables add up. To me they are crucial to high quality work. Vibration is unacceptable for custom made $60,000 sleds. I can buy a nice Mercedes for that much... and it doesn't vibrate.

The reason I go into all this is because it takes us operators being aware of these things and holding the manufacturers to a high standard that things move forward. Otherwise, they are just happy to take your money... and lots of it.
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#5 Peter Milanov

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Posted 17 January 2007 - 11:17 AM

I had the same problem. After some talk to Tiffen I got hold of Kyle Young that explained that one source of this problem are with the top plug that connects the post with the tilt stage. The early Ultras had a weaker, smaller top plug that later got replaced with a beefier one. I´ve enclosed a picture of the old plug, if you have this one you better get it replaced (it´s a $1000 upgrade). I´ve noticed a great improvment after upgrading.

Also, I have been bugging Tiffen to let me buy the new Ultra 2 topstage to replace the old one, but Frank Rush told me they have no plans on offering this part separately... But if more people are asking for it they might have to reconsider.

Attached File  top_post_plug_1.jpg   67.76KB   240 downloads
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#6 Matt Burton

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Posted 17 January 2007 - 12:21 PM

Also, I have been bugging Tiffen to let me buy the new Ultra 2 topstage to replace the old one, but Frank Rush told me they have no plans on offering this part separately... But if more people are asking for it they might have to reconsider.


I think that it's disgusting that they won't sell you the new ultra topstage separately, sounds like corporate madness.
-matt
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#7 Alec Jarnagin SOC

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Posted 17 January 2007 - 12:46 PM

Will,

As usual, very articulate. Yes, vibration is our enemy and it amazes me at how often it is overlooked. Obviously, everyone has their own threshold of acceptability and let's face it, solutions to the problem often come with the price tag of weight or even convenience. I, too, use the XCS 2" post for the reason Will states as well as using a DB3, and XCS plates. There is no doubt that these things all add a little weight when compared to other options (I'm comparing the weight of the post with other 2 stage posts). None of these are significant though and I feel they truly make for better shots. Others will accept a smaller attachment point at the top of the post for the flexibility of the four-stage post. Some will give up the luxury of the side-to-side bearings in the top stage for the extra rigidity.

It sort of goes back to a fundamental belief I have: the more complicated the plumbing, the easier it is to muck up. Features are great, but I don't want them to cost me too much rigidity. Of course, we still need to be able to do our job. The most rigid rig out there would be a camera permanently fixed to a post with a fixed lens and fixed accessories because you wouldn't be able to adjust it (not very useful).
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#8 Jerry Holway

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Posted 17 January 2007 - 02:18 PM

Once you start getting really into this, look at the diameter of the post where it meets the top stage. For all the integrated 4 stage posts, that diameter is smaller than the diameter of the post that the gimbal is on. While I understand why this has to be for a 4 stage post, I hate the idea that at the place where you need the best connection possible, why one would shrink the footprint and attach with a smaller base. This is why I much prefer to carry less weight in a 2 stage post and have a separate super post for long work. By having a 2 stage post, the diameter at the top of my post actually increases (shock, horror!) from 2 inches to 2.5 inches and almost 3 inches in diameter by nature of how the bottom of the top stage is constructed.


Will-

I generally agree with most of your points, and you are certainly on target with all of them.

One minor exception is the above. Flexiblity/vibration is related to both the material/construction, post diameter (both inner and outer), and post length - the latter by more or less by the cube law (double the length and it's eight times more flexible). One reason that the Ultra's smallest post diameter is on top is that when it's stressed with a heavy camera, it's typically very short (with less flexing by the cube law), while the sections furthest from the gimbal actually need the biggest and stiffest diameters, again, because the difference in diameters is not as important as the length of the posts. Not intuitive, granted, but true.

Flexing in the Ultra top stage can be reduced via the methods you mentioned, and by tightening all screws, and pre-loading the bearings. All vibrations can be reduced using the provided stiffening system, which reduces vibrations from the battery and monitor rods as well.

Be sure to tighten everything down well - I've done this many times, and done the wedge trick, too. - But frustrating - hence the new stages in the Clipper twos, Archers, and the Ultra2, as well as improved and stiffer monitor and battery mounts.

As for selling the Ultra2 top stage separately... ultimately, I think it's a good idea, but right now I know they are working hard to get them out the door with the rest of the sled attached. Making them backwards compatible is not as easy as it may seem at first blush. There are electrical differences (different connectors, numbers and types) as well as mechanical ones (devils in the details to the nth power), which would require different cabling harnesses or adaptors, all of which have to be designed, tested, thought through.

Jerry
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#9 Lohengrin Zapiain

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Posted 18 January 2007 - 10:19 PM

Wow... thanks guys,

I have a lot to digest with all this information and new things to try with my Ultra. I guess I'll have to learn to live with certain amount of vibration and I will also learn to control it.


As for the Ultra top stage connector I guess I will check that out and replace in case I have the old one.
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#10 WillArnot

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Posted 18 January 2007 - 11:33 PM

Alec, thanks man for your helpful summary and clarity where i tend to get long winded. Certainly, to each their own.
Jerry. Thanks for that. It is counterintuitive at first but makes perfect sense.

I should stress that although i did still witness some minor plate flex I was extremely impressed with the new Ultra 2 and Tiffen, and Garrett's, and your dedication to constantly improve the integrity of the Steadicam. I love the small size of the new Ultra 2 bottom. The new top stage is a big step in the right direction finally, and the centering ability of the gimbal is damn sweet. I have always been envious of the tilting head. So handy for low mode work and maintaining dynamic balance w/ tilt angles.

I was at Woodland Hills Panavision today, starting my first foray into the Genesis world. I will be giving Tiffen a call tomorrow regarding a possible power cube order. I will continue this in Batteries.

Will
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