Learn to Read the Spin Test - A Guide for Achieving Dynamic Balance with Your Steadicam
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- čas přidán 26. 06. 2024
- Timestamps:
00:00 - Introduction
00:37 - What you need to do before the spin test & an important process to remember
03:17 - Purpose of spin tests & basic physics behind the dynamic balance
06:23 - Spin test results, how to read them & physics that help you understand them
10:29 - External links of useful knowledge (This is important too)
Useful Links:
Steadicam Dynamic Balance Quick Guide - by Chris Fawcett
• Steadicam Dynamic Bala...
(The section that Master Chris talks about the pattern behind the 3 masses' positions is at about 2 minute mark in that video)
A Dynamic Balance Primer - by Jerry Holway
people.ok.ubc.ca/creative/Gli...
Music Credit:
Sail Away - by AG Music
Bright Day Ahead - by Geoff Harvey
Elegant Commercial Piano - by Roman Cano
from Melody Loops
Additional Notes ↓↓↓
There is a brilliant question being asked in the comment section about how one would assume naturally to move camera forward if sees the lens tilts up, I then realized I didn’t do a good job explaining this clearly enough in the video. After that, I took some time to think about how I should explain it a bit further and I wrote this reply which I just copy-and-pasted here for anyone who might have the same question. Hopefully this could clear up some of the confusions, if so, it’ll be great:
--------------------
“
There are 3 masses we are dealing with here, camera on the top (C), sled batteries (B) and sled monitor (M). The sled will only be in dynamic balance when all 3 masses are in the spatial positions relative to each one another.
Figuratively speaking, it is much like trying to solve the equation of “C + B + M = 10”. Besides the infinite combinations of the positions there are, what we are aiming to do in the video is to fill in the numbers into the equation, so that we will reach one of the infinite combinations that 100% gets the sled in dynamic balance.
In the video, once we have the monitor in the desired position, we will never move it again during the rest of the balancing process. Figuratively speaking again, this is like algebra, now we have “C + B + 5 = 10”.
In the rest of the balancing process, we put/fix the camera on the top in position, and then get the sled in static balance by changing the battery position only. Once done, we do the spin test. If the sled spins in dynamic balance, it means we hit the jackpot and now we have reached at one of the infinite solutions. (It could be “2 + 3 + 5 = 10” or “1.3 + 3.7 + 5 = 10”, so on and so forth…, we just wouldn’t know exactly the value and yet we don’t need to know.)
If the spin test does not show the sled spinning in dynamic balance, we change the camera to new position (this act will ruin the current static balance), and we’ll need to get the sled back to static balance again by changing the battery to an also new position. We repeat this process until the sled spins in dynamic balance during the spin test.
***
With the understanding of the above, when the lens tilts up during the beginning of the spin test, it does NOT mean “back heavy”. Remember, our sled should be in static balance in the first place, before the spin test. Therefore your camera does not make your sled back/head heavy.
What you are observing (the lens titling up), is a combined effect of the pendulum and the spin. Dynamic balance is the spin without pendulum. The pendulum is caused by the camera being away from the pivot point.
P.S.
Ideal situation to prove there is a pivot point, imagine camera in the dead center on top with 2 equal weights on the sides of the bottom of the sled. This will be a “0 + 5 + 5 = 10” situation.
”
Great video Anthony
Oh, this guide is surprisingly good! 👏
Very hepful!
I'm glad it is helpful!😊
Congratulations for this awesome tutorial, perfectly explained and helped me to get a perfect dynamic balance. Thanks a lot!!!
You're welcome, man! I'm super glad this video is helpful to more and more people!
Super helpful. I wasn’t able to get my Steadicam into dynamic balance until recently. I actually had to re-center the gimbal on my Archer 2 because it was off. Very nice explanation and excellent animations. You’re a great editor.
Thanks for your kind words! I'm glad this video is helpful! I had off centered gimbal with my rig too last year. I have the volt system on the gimbal and it needs to be disassembled first before the gimbal can be re-centered. Since I don't know how (even after seeing a video instruction), I end it up sending my rig off for repair. Now it's all good.
Great Tutorial!
Thanks very much, Evan!
Brilliant!
Thanks so much! Sorry, I've been away, hence the 1 year reply. Nonetheless, I gotta say express my thanks!😊
Great video🤗
Thanks very much 😊
Thank you for this amazing tutorial. I have a question. My glidecam doesn't have internal cables, so I need to have a cable that runs outside the sled between the camera and the monitor. I have freedom of movement when operation, but I cannot spin the sled 360 degrees. How can I check the dynamic balance in this case? Thank you very much
Thanks, man and sorry for the late reply!
Would it be possible to do the balancing first and then plug in the cables?
I did run into situations when my internal cables failed and we had to plug cables directly from the camera to my monitor to get feed. Not ideal, since loosen cable shifts the balance.
We did the balancing first, then looped the cable over my shoulder (we had a very long cable) and someone was holding it behind me to prevent the gravity from making the cable drag my sled.
I know that may not be your situation, you probably have a cable with the right length, it's just being external.
👏🏾👍🏾🙏🏾
Thanks very much!❤
Antony this is super cool tutorial ! I have one question. I have problem with dynamic balanced steadicam in low mode. Do you have some tips in that situation?
Thanks, man! Sorry for the late reply!
Theoretically, the method in the video works the same with balancing in low mode. We can do the same thing with the spin test after we put the sled on the balancing post and flip it over by adjusting gimbal position (making the camera mess side heavier).
There's one thing that may make things trickier, that is when your monitor and batteries are extended too much. Say, if it's extended longer than your camera mess, then your sled looks like a "T" in low mode. (Hopefully, I'm not making things more confusing...)
Usually, this won't really happen, since most of the camera builds we'll be flying are quite lengthy anyway. However, if it happens, adjusting the monitors and batteries' distance to match with the length of your camera build you're flying, will make balancing easier.
Generally speaking, if you get your sled in dynamic balance, it won't be too far away of getting back in dynamic balance when you flip it upside-down.
Hope this helps,
Cheers,
Antony
Great Video and tutorial! Thanks for upload! I'm only a "Glidecam Operator" but... who cares :)
Thanks! I'm super happy to hear that you think it's good :)
@@antonyzhao5394 You're welcome! Very good explained, also with animations! Great
Thanks for ur knowledge …buf ;( so take time if i do like that because maybe u try 2-3 more time for this. On the set we don’t have enough time…
True! This may not be the best way, but just one way to do it. Once the operator has enough experience with one set up, they don't need too many tries at all. Even if they try this way, shouldn't take longer than 3 minutes. :)
The pan-bearing on my steadycam-gimbal is a bit "stiff". The bearing that is active during your spin test.
So, if I myself do a 360, the lens does not stay in front, but is off by like 10-20 degrees.
What can I do to alleviate this?
Thank you.
Deeply sorry for the late reply! I've been away for a while. The bearings should be smooth if they are in genenally good condition. What model of steadicam are you using? Can this steadicam brand's distributor conduct a service for your gear in your local area? If your steadicam rig is new, "stiff" might not be a good sign, if the rig is used for a fairly long time. the bearings might need to be cleaned during service, especially if you have been working in the desert or beach where sand can get in.
So if the camera is tilting up it means it is a bit back heavy or not? Doesn`t moving the camera backwords makes it worse?
It’s a bit confusing, I know. I’ll try my best to explain.
There are 3 masses we are dealing with here, camera on the top (C), sled batteries (B) and sled monitor (M). The sled will only be in dynamic balance when all 3 masses are in the spatial positions relative to each one another.
Figuratively speaking, it is much like trying to solve the equation of “C + B + M = 10”. Besides the infinite combinations of the positions there are, what we are aiming to do in the video is to fill in the numbers into the equation, so that we will reach one of the infinite combinations that 100% gets the sled in dynamic balance.
In the video, once we have the monitor in the desired position, we will never move it again during the rest of the balancing process. Figuratively speaking again, this is like algebra, now we have “C + B + 5 = 10”.
In the rest of the balancing process, we put/fix the camera on the top in position, and then get the sled in static balance by changing the battery position only. Once done, we do the spin test. If the sled spins in dynamic balance, it means we hit the jackpot and now we have reached at one of the infinite solutions. (It could be “2 + 3 + 5 = 10” or “1.3 + 3.7 + 5 = 10”, so on and so forth…, we just wouldn’t know exactly the value and yet we don’t need to know.)
If the spin test does not show the sled spinning in dynamic balance, we change the camera to new position (this act will ruin the current static balance), and we’ll need to get the sled back to static balance again by changing the battery to an also new position. We repeat this process until the sled spins in dynamic balance during the spin test.
↓↓↓
I’m sorry! I took a long detour to answer your question. Here we go: With the understanding of the above, when the lens tilts up during the beginning of the spin test, it does NOT mean “back heavy”. Remember, our sled should be in static balance in the first place, before the spin test. Therefore your camera does not make your sled back/head heavy.
What you are observing (the lens titling up), is a combined effect of the pendulum and the spin. Dynamic balance is the spin without pendulum. The pendulum is caused by the camera being away from the pivot point (reaction point). I hope this will answer your question and not giving you more confusion.
P.S.
Ideal situation to prove there is a pivot point, imagine camera in the dead center on top with 2 equal weights on the sides of the bottom of the sled. This will be a “0 + 5 + 5 = 10” situation.
@@antonyzhao5394 Hey Antony, thanks a lot for this detailed answere. I think I got it now :)
@@AlexFlatoni You are very welcome :)
What it’s the use of dinamic balance ? If u ask to go with the camara pointing down or up and then u must move it fowards or backwards on you top stage
It's a fickle thing. A steadicam sled with dynamic balance helps you to control the inertia while operating. That being said, I knew operators don't care much about dynamic balance and still be able to deliver their shots with no problem. All the "pointing down or up and then u must move it fowards or backwards" shenanigans in my video, it's just me trying to strip the complex physics down to something that work fast enough to achieve dynamic balance in general conditions. If it helps, hooray. If it doesn't, well...then I need to work on it, haha.
Okay, so this part of dynamic balance makes sense, however when I go to balance my sled I’m also getting a side to side swing as well as a back to back swing.
I initially assumed this meant that my camera is not placed correctly or that one side was heavier due to the Viewfinder (for example on an Amira)
However despite getting the sled in static balance I’m still getting this spiralling side to side back to front swing that I can’t seem to resolve.
I want to assume that if my camera rig leans to the left it means I need to shuffle my camera to the right? - though I don’t know and I’m struggling to find an online solution…
I’m fairly new to this and I imagine with time and experience I’ll fix it…
Any solution found ? Maybe this is a gimbal centering issue ?
@@bastienchill it was worse!!
My head on the sled was skewed by 1-3 degrees off to my bottom 🫠 I have to rotate it back almost ever 2nd job because the only thing keeping it in place is a quarter screw tightening clamp……
Just gotta wing it till I can buy a better sled. - and also yes, I think my gimbal might be out but it’s survivable
@@matthewshanks3684 I am facing a similar issue but cannot get my dynamic balance right, even after adjusting the gimbal centering. Lining the top and bottom stage is indeed the other option. I will probably take the screw off the top stage to re-align it properly. Looks like it will be long guessing/testing steps to find the right spot…
@@bastienchill oh yeah, I did mine by holding the sled horizontally and then rotating the alignment by eye.
Though I’ve been thinking of setting up a tool of some sort I can use to calibrate my sled alignment more accurately.
The other common issue I’ve seen is not aligning the base plate on the camera correctly, whether this is the Steadicam plate or the cage/ plate on camera.
The one thing I’d recommend is if you have static balance on your sled but still getting a weird wobble, hold the sled up as if your doing a drop test but face the front of the camera/lens to the sky, let it drop and if it goes to the left or the right that could mean your top and bottom alignment is off, if not it could just be your dynamic balance is off in which case following the video above will save you hahaha.
@@matthewshanks3684 thank you for your detailed recommendations, it’s very valuable !