February 9th, 2007, 11:49 AM | #31 |
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Thanks for the detailed explanation, Charles! I am so thankful that you are on this board!
So, are you saying that an iso-elastic arm will stay in its vertical spatial position if you placed it there and let go??? In the sled, it is perfectly balanced when you can put the post at any angle and it stays there without effort. If it is unbalanced, the camera will tilt or roll or basically move. Of course, proper operation of the sled is to make the sled slightly bottom heavy so the weights stay on the bottom... :) So is iso-elasticity the equivalent of a vertical displacement balance? Or did I just totally misunderstand iso-elasticity? Thanks again for explaining this concept to me, Peter |
February 9th, 2007, 12:00 PM | #32 |
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A truly isoelastic arm will indeed stay where you put it. However, that can be a little disconcerting to operate, and the arm may not "track" properly (the two sections of the arm lifting at the appropriate rate in unison). The larger Steadicam arms allow one to dial in the appropriate amount of isoelasticity to taste, while the Flyer and Merlin arms have it pre-set. Having less of an isoelastic feel simply means that a certain amount of lifting force is required by the operator, but it turns out that this is more natural for most people and it is still much less than an arm that has no such feature.
The balance of the sled and the action of the arm are two separate systems, so it's probably not worth trying to draw a commonality between them except that they work together to achieve the effect of the stabilizer. If I had to compare the two actions, I would say that you balance the sled, and you tune the arm. The balance of the sled is minute and absolutely critical, whereas the arm can still function over a wide range of settings, but one tunes it to where one likes it.
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February 9th, 2007, 12:59 PM | #33 | |
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Having played with lesser hand-held stabilisers, and with the Merlin (albeit briefly and without any skill in balancing), the miniscule masses involved required a huge amount of zen to guide the camera, and most of the time the camera seemed to know where it wanted to go. A bit of stiction would seem to be an asset in these circumstances - the 'ideal wetware arm' if you like. |
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February 9th, 2007, 01:39 PM | #34 |
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Again, though, we are talking about two different components: stiction in the gimbal will affect the angular axes (and make the camera feel like it has a mind of its own) while the action of the arm has to do with the shock absorbing and vertical travel capabilities. Stiction in the arm will make it feel like a rough ride, but it won't cause the camera to veer off necessarily.
But yes, the original iso-elastic Steadicam arms (Master series) were prone to stiction largely due to the bearings being used. The current generation are beautifully smooth.
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February 9th, 2007, 06:20 PM | #35 |
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brilliant info thanks so much.
i'm obviously too cynical for my own good...reading words like 'isoelastic' as meaningless marketing drivel....but Charles has given it meaning and made clear an absolute distinction in the steadicam brand which all previous threads i'd found hadn't...and mr tiffen uk didnt draw my attention to either. So useful, thanks again. I have to ask though, have i got this right....steadicam achieved isoelasticity, then provided a means of dialling it out because it wasnt entirely desirable to operators, so in most instances of use they are not isoelastic. Meanwhile steadicam patent what, the term 'isoelastic' or the characteristic?...so other makers can presumably only make (for want of a better term) nearly-but-not-quite-isoelastic arms? So is there actually only a marginal (isoelasticity)difference in use between steadicam and some of the 'good' others? i could see this as being marginal but of great significance in heavy flying, but surely less so as weight drops. I bet im coming across as incredibly pedantic! On the subject of wires and pulleys i'm now wondering if this design is aiming towards isoelasticity?? http://www.floatcam.co.uk/floatcam-showreel.htm Thanks again. |
February 9th, 2007, 07:03 PM | #36 |
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Reading backwards again i'm thinking my points have already been adressed really so apologies for the above.
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February 9th, 2007, 11:51 PM | #37 |
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I'll be honest with you chaps, I have not been an owner of the Steadicam brand gear for over 10 years now so my knowledge is somewhat peripheral (sort of like what one knows of a Sony camera if you own and use a Panasonic). So there may be slight discrepancies in what I'm saying, technically speaking. Perhaps Mikko can chime in and clarify if I make a boo-boo.
I believe that the principle of isoelasticity as defined by the Steadicam patents deals with the dynamic deflection angle of the spring force as the geometry changes within the arm, which maintains continuous tension. The only other technology that is able to achieve this is the compression spring canister system in use in the PRO arm (and "knockoffs" of same). The trick is finding just the right amount of isoelasticity that the arm feels natural, much in the same way that a slightly bottom heavy rig is more natural to operate (although a few intrepids prefer a more neutral rig, which doesn't work for me at all). The real bottom line with this is that if one were to analayze the group of freaks and miscreants that are full-time Steadicam operators, an extraordinarily wide range of preferences and operating setups emerge. That is to say, for most videographers who own Betacam-style cameras, for instance, 9 out of 10 will have virtually identical setups, while the same sampling of Steadicam guys will turn up any number of individualized bits and pieces, custom modified parts and fiercely different techniques. I experienced this just today when I was testing out some new gear in the presence of 3 other operators...nearly everything we discussed involved a "really? I don't feel that way at all" or "I've never even considered doing it that way" etc. So when it comes to isoelasticity, the higher-end arms that allow for adjustment are there to please the individual operator's preferences (imagine a car that is not just either standard or automatic transmission, but could be dialed between the two in increments--now THAT would be heaven!) The lower end rigs do not offer this adjustability simply because that level of operator is less likely to feel the need to tweak, being more accepting of whatever is given to them. And finally--geez, what a long-winded rant I'm on--having tried both the Glidecam Smooth Shooter and the Flyer (and now the Merlin) setups, I can honestly say that while the GC is a nicely made piece of gear and works fine, there is a substantative performance difference between that and the Steadicam arms--it's not just a hype/brand name/catchphrase mentality...and remember, I don't even own Steadicam gear at the moment.
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February 12th, 2007, 10:31 PM | #38 |
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Heh, thanks for the deferral Charles. No boo-boos in your comments :)
I will however add my highly simplified "version" of the description of Iso-elasticity into this already overlay complicated mix of discussion! I like the describe the Iso-elastic performance of an arm as how "bouncy" it is. > A non-Iso-elastic arm will be very bouncy and, as Charles noted, wants to return to it's center point and therefore needs more effort to lift or lower from that neutral point. > An Iso-elastic arm is less bouncy and pulls to it's neutral position even less. At the extreme it doesn't pull at all, but can in deed remain where you leave it. I've done that with a G-50 arm once. It was amazing, but as Charles notes; also very strange. ----- And, because I feel this post is too short, now for a bit of the tech behind the arms.. The less tension (strain) a spring is under, the more bouncy it is. The tighter you pull a spring, the less bouncy it seems - as more energy is needed to make changes in tension. You can test this with a rubber band: Pull it tight, and then notice how much less "stretchy" (bouncy) it feels. With a the springs of a Steadicam type arm at a certain tension, the arm can become Iso-elastic. > The earlier ("original") Steadicam arms - Up to the Model 3a & EFP arms, where not really "Iso-elastic" arms, as they where pretty bouncy. However when you had them adjusted to maximum payload (by tightening the springs), the arms became almost Iso-elastic. But, as soon as you loosened off the springs to carry less weight, the arms became bouncy again. The Patent has expired on this original arm design, and this is essentially how every non-Steadicam Brand arm works & performs. - A Glidecam Smooth shooter arm for example should become less bouncy as you load it up with more weight. The same applies to all non-Steadicam arms, including the aforementioned Pro arm. > The newer Steadicam arms (Starting with the Master/Ultra arm, now including the G-series, Flyer and Merlin arms (and the ProVid/SK arms too)) are built in such a way that instead of changing the tension of the spring to adjust carrying capacity, you instead change the end position of the spring and it's mechanical advantage. As the Spring tension doesn't change, the arm can be built with the spring pre-tuned to a state that provides for Iso-elasticity. THIS is why they are called "Iso-elastic" arms; because they remain turned to be Iso-elastic regardless of the adjustment of carrying capacity. Steadicam still has active patents on this design, which is why no other manufacturer can offer a "Iso-elastic" arm, that remains Iso-elastic as you adjust it's carrying capacity. > The G-series of arms takes this all one step further, and combines the systems! You set the arm's carrying capacity ["Lift"] by moving the spring, and then you set the arm's Iso-elasticity (bounciness) ["Ride"] by changing the spring's tension. This is the fine tunability that Charles mentioned that only becomes necessary at higher levels of operating. Every operator has their own personal preference as to how Iso-elastic they like their arm. Some like it bouncier, some like it almost invisible, most like it somewhere in between. It's all part of the decision when choosing an arm. Whew, OK, that got a little detailed, but hopefully it clears up some questions about what arms are and aren't Iso-Elastic, and why. - Mikko
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February 12th, 2007, 10:49 PM | #39 | |
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February 12th, 2007, 11:01 PM | #40 |
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Oop, yeah my bad on that one.
The Pro arm does act differently to most arms. But it's not paticularly Iso-elastic if I recall? It's been a while since I flew one. - Mikko
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February 13th, 2007, 12:17 AM | #41 |
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The PRO arm is not technically iso-elastic, but it acts similarly to one in that it is, as you say, not particularly "bouncy". In other words, it's like an isoelastic arm that is tuned down a bit to give it a bit of feedback, the way most people like it. It requires little force to hold up or push down, especially when compared to any other non-isoelastic arm.
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February 13th, 2007, 11:21 PM | #42 |
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Hey guys here is a trailer that almost all of the footage I shot with was used while doning the new vest and arm that I field tested for Steadicam 2 weeks ago. Note that this trailer is part of my product which is a quick hit for my customers and is not designed to feature the much longer shots that show the incredibly smooth sustained shots. I also had no test time with the rig I got it in and brought it directly to a 13 hour shoot. Since it is a prototype there were no instructions prepared. I am also self taught and have never taken any steadicam classes nor any normal camera operation classes for that matter.
http://www.firstsightpictures.com/de...hptrailer.html I am also relatively new only shooting around 60 weddings in the past 2 years, but I am a tool freak and have a ton of camera accessories. Currently my tool of choice is a Glidecam smooth shooter with a custom mount for the Steadicam Merlin. I also have the Glidecam 4000, which is used with the smooth shooter before the Merlin was released but I rarely took it out on wedding shoots because if I did I would have to make two gear runs to get my cameras and the rig. When I got the Merlin I was blown away by the ease of use compared to the 4000 sled. You can make trim adjustments lighting fast and it is easy to switch to different shooting modes. When I got my 4000 I recall complaining to the awesome Dave Williams that when the camera went off the front axis that I balanced it the camera would start spinning on it's own. He informed me that this was a challenge with dynamic balance that took steadicam many years to master and is only handled well with very expensive rigs. So when I got the Merlin the most impressive feature to me was the way it handled the dynamic balance problem. Besides the poor trimming system of thumbscrews and crappy industrial washers to counterweight that the 4000 sled has it was also too frustrating to achieve and keep dynamic balance. Moving off axis you have to assert too much control pressure to keep the camera trim. With the Merlin I could trim in an instant assert no control pressure while walking around it 360degrees and it would maintain perfect dynamic balance. So the with the incredible dynamic balance, trimming and other features coupled with the extreme portability of the Merlin gave me the idea to get an attachment designed so I could mount it to the Smooth shooter and run the Merlin for a full shooting day. So now with my rig I could also carry all my gear in 1 trip. I could put on the vest with a camera bag in 1 hand, tripod bag in the other and a small camera backpack on each shoulder for a 3 camera shoot. The spring arm and Merlin would collapse and stow in the back of just one of the backpacks. When I'm transporting gear I definitely look like SWAT, but it is the lightest fastest transport, setup and breakdown for run and gun style shoots where you need tools that help you attempt to make a run and gun look like a cinematic style production. So to make a longer story short…. I got the opportunity to test this prototype and compare it to my current rig and needless to say I was blown away. I really love the smooth shooter but hate the 4K sled, but compared to the new arm the Smooth shooter now feels like it now belongs in the garage with the sled. I used to think the smooth shooter was effortless to move through the boom range which is from the waist to the upper chest, but the new arm is truly effortless, actually incredible.... I could move the camera from my knees to just above eye level with truly no effort it was actually a bit freaky feeling. Almost like I was guiding the camera with my mind..... To adjust the spring arms on the smooth shooter you have to have an allen wrench to adjust the springs. With this new arm in less than 1 minute with the rig flying I could switch out a WA on the camera trim it and then very easily adjust the arm with very simple turning of a thumbwheel located on the top of each arm. The only thing I did not know is there are also fore and aft adjustments at the arm mounting point to further tweak the balance, but it didn't really matter because with the adjustments I was able to figure out and make I was pissing myself with how good it was compared to my current rig. The vest is also much less bulky making it lighter, less noticeable and it was much easier to travel with. I can see putting this in my baggage taking up only a little more than half the space of my current vest. So I was able to run the rig for almost the entire shoot. I did not use it for prep, but started at preceremony and wore it through the entire ceremony and post ceremony which was Catholic and the total time running the camera without dismounting was over 2 hours. Much of the ceremony I would also operate at full zoom and still have tripod like shots. Then I traveled to the reception site and did 1 hour of cocktail and photo session and then ran it for majority of the reception through all of the main dances and very long toasts. So I shot about 4 hours of footage on the rig. Sadly since going full time my only physical activity is on the weekends that I shoot otherwise I sit and edit all week, so in the last 2 years I have gotten very out of shape and have gained over 20 lbs, but at the end of the night I had only a minor fatigue. With my normal rig I would get a very harsh burn in my lower back. So with the portability, ability to fly and then immediately dismount lock the arm to my chest and shoot handheld style makes this my dream production rig that I would take to every shoot. Needless to say I was seriously considering not sending the rig back Monday morning and telling Steadicam they would have to come take it from my cold dead hands.... |
February 13th, 2007, 11:50 PM | #43 |
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Bruce:
What you are describing as dynamic balance is actually a non-linear gimbal, i.e. the center of rotation of the gimbal does not line up with the center of the rig, which causes it to fall in one direction or another when clocked. Dynamic balance has to do with the distribution of masses at the top and bottom of the sled. A rig that is out of dynamic balance can be statically balanced (no matter where in the pan rotation you place it, it will stay level, unlike the situation you describe) but if you were to spin it continuously, you would see it predictably and repeatedly lose level on each rotation. It's complicated stuff. Fortunately you don't have to worry about that with the Merlin. With a Glidecam, assuming that the gimbal was linear (which apparently yours wasn't), the dynamic balance could be tweaked by shifting washers at the bottom, either along the slots or by actually redistributing how many are front and back, and then sliding the camera fore and aft to compensate.
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February 14th, 2007, 11:25 AM | #44 |
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Great review Bruce!
Your footage looks really good. I can see that the Merlin Arm will be huge for wedding & event videography. - Mikko
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February 14th, 2007, 03:26 PM | #45 | |
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