Proper sandbag placement advice for newb?

K

kat.hayes

Active member
I have read lots of conflicting info regarding the best way to stabilize C-Stands with sandbags.

I am pointing the largest leg of the stand in the same direction as the weight from the light or gobo arm, and I am placing the sandbag over this large leg (see attached images).

1. Is this the correct way to place my legs? I am able to spread my legs out in different ways, I just picked the way that seemed the most stable.
2. Is this the correct way to place my gobo arm, light, consistent with the direction of my legs?
3. Does the sandbag placement look correct?

Thank you.
 

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Well for starters, unless the angle of the picture is messing me up you need to get that arm going the other way. It's best to have the weighted side of the arm to the right when facing the knuckle/tightening knob. This way the weight is going down in a way that tightens the knuckle. If it's to the left, it's loosening the knuckle and may fall.

As for sandbag placement I too hear tons of conflicting information at all levels of experience. The important thing is to know whether it's secure or not. The way you did it is common, makes sense but you've already got the weight over a leg so I don't see a TON of use in putting even more weight on that leg, seems redundant. I prefer having the weight of the sandbag on the other side acting as a counterweight.

This usually means either two sandbags, one on each opposite leg, or wrapping it around the stand from the other side. But that also makes it easier for the bag to fall off. Just make sure it's secure.

Also make sure the sandbag isn't resting on the floor, otherwise the thing will already be falling over before the sandbag starts doing any good.
 
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For the photo on the left: When you said “you need to get that arm going the other way” “It's best to have the weighted side of the arm to the right when facing the knuckle/tightening knob.”


1.) I’m not sure what you meant by getting the arm going the other way? What is the weighted side of the arm? Do you simply mean that I should put the tightening knuckle on the opposite side of where it currently is?


2.) Are you suggesting to put the sandbag on a leg in the back to counter the weight from the arm/light? I could also just add a 2nd sandbag to a back leg and keep the one where it is.


Thanks!
 
In regards to the knuckle/arm...

I can't really see what the deal is from that picture, so you tell me: Is that knuckle, the twisty handle thing that's facing the camera... when you twist it, is it just for the mount to put the arm/head on the stand? Or does it open the head itself? Meaning if you twist it, does the head open up so you can slide things into the holes, then tighten it again?

If it's the former, and there's another handle in the back I just can't see, then nevermind.

But if it's the latter... it's like this. The weight of the arm, meaning the side that has the light on it, needs to be pointing to the RIGHT when you're looking at the handle (so in the picture above, viewing it from the camera's angle, the side with the light on it would need to go to the right). This is because that weight on the arm is pulling the arm down, which is twisting the knuckle. Since we twist it to the right to close it, if the weight's pulling it to the right, it's tightening the knuckle and keeping it locked. All good! But if it's to the left, it's actually opening the knuckle, which might cause it to come loose and the light will come crashing down. You can test this by grabbing your arm, putting it on a stand and pushing down on each end of the arm. See how the side that's going to the left opens up? And if you push hard enough, the whole thing will come loose. But the side that you push to the right is locked and steady.

As for the sandbag, if you want to put a second one on the back, go for it. Often there's not enough sandbags or it's not worth the time to run and grab another, since usually one sandbag on a properly mounted and rigged stand/light will be enough, but if you can spare the bags and the time it won't hurt.
 
i thought i heard/read something about the idea being that the sandbag reinforces the center of gravity or some such, and thats why we bag the tallest leg/leg under the weight. also the reason you sometime wrap the bag around the column itself rather than drape it over ANY leg.
 
As I understand it that looks correct except for the knuckle issue. The counter intuitive physics behind putting the sand bag on the same side I guess is because the issue of stability concerns the c-stand being bumped. If it is not disturbed it doesn't matter where the centre of balance is, so long as it is inside the footprint of the feet. Unless it is bumped it doesn't matter if it's dead centre or 1mm from the edge.

If you weight the intuitive back leg it does a few things. It is intuitive to put the sandbag there because it brings the centre of balance towards the centre of the footprint.

But...

I think placing it as you have does a couple of things. First if the sandbag comes off it should still not fall over since it should have been balanced before the placement of the sandbag and the long leg is in line with the weight. Bagged behind if it comes off there is a momentum from the centre of gravity shifting even without a bump. If the centre of balance is already too close to the edge of the footprint it could go over just from that. Second if it was weighted at the back and it gets knocked backwards then the sandbags will enhance rather than reduce that momentum, and couple that with the boomed weight shifting to the rear as the angle changes. Also two legs provide a stable pivot hence less resistance to the momentum. Further if you only use one bag then as the stand shifts you may get a torsional factor that twists the stand as it comes down.

I'm sure the pros know the real answers but my high school physics approves this method.
 
Knuckle on the right, big leg towards the weight, sandbag on the big leg. If you need more bags there's a good chance you are using the wrong stand, but best to wrap it around the leg so it isn't touching the ground.
 
In the 1st picture, the knuckle is on the stand the opposite way from what it should be. The part where the arm is going through should be on the ⅝" pin on the stand and the arm should be going in between the circular pieces through the ⅝" hole. And in the second picture, it looks like the high leg isn't open all the way, the only time we really do that is if the stand is right up against a wall.

That sandbag placement is fine when the weight isn't too off center. Remember, only arm out when you need to, try to keep it vertical and move the whole stand to where it needs to be to support whatever it's holding in the right position. But if you do have to arm something out and it feels like it'll tip over, wrapping the bag around the the riser column helps.
 
Fascinating. I've heard that the sandbag should be wrapped/tied around the central pole, on the grounds that it then can't fall off, and its central weight makes the main 'tripod' of feet more stable...
 
Thanks for all of the replies, I am a bit confused still. With regards to the knuckle issue:

1. In Photo 1, are the knuckles what I have labeled as #1 and #2?
2. If so, my understanding of all the responses is that I simply flip both of these to the other side?
3. In Photo 2, are the knuckles what I have labeled as #1 and #2 and #3?
4. If so, my understanding of all the responses is that I simply flip all of these to the other side?


Thanks!
 

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Moseph said:
In the 1st picture, the knuckle is on the stand the opposite way from what it should be. The part where the arm is going through should be on the ⅝" pin on the stand and the arm should be going in between the circular pieces through the ⅝" hole. And in the second picture, it looks like the high leg isn't open all the way, the only time we really do that is if the stand is right up against a wall.

That sandbag placement is fine when the weight isn't too off center. Remember, only arm out when you need to, try to keep it vertical and move the whole stand to where it needs to be to support whatever it's holding in the right position. But if you do have to arm something out and it feels like it'll tip over, wrapping the bag around the the riser column helps.
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Agreed.


Impact-C-Stand-Review.Still006.jpg
 
This topic is a joke one, isn't it? Then correct place for extra ballast is the place it's needed for the weight and position of the items it's assisting not falling over. It's just physics lowering the centre of gravity to a place inside the area contained within the support footprint. I means slinging the legs to assisting the balance instead of compromising it, and placing extra ballast in the opposite direction. Move the load, and you need to re-ballast.
 
http://www.dvxuser.com/V6/showthread.php?312340-correct-way-to-sandbag-a-c-stand

The above thread, which you should have found by searching, tells you what I found out. That is, put the longest leg under the weight bearing arm, and wrap the sandbag around the shaft with the sand directly opposite that longest leg (between the other two legs). This method gives maximum support to the weight, and pushes the center of gravity back towards the central shaft where you want it. There's a picture in the above referenced thread (post #9) that shows what I just described.

Try it. Indeed, try them all. See if you can find better stability than my method. I couldn't, but that's just me.
 
i think it depends on the available bags too, right? some are designed to wrap around the column and " stand up", some are not shaped right for that and are too floppy.
 
sonofaresiii said:
Well for starters, unless the angle of the picture is messing me up you need to get that arm going the other way. It's best to have the weighted side of the arm to the right when facing the knuckle/tightening knob.
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This. And contrary to many opinions here I was taught the tall leg should be under the weight with your sandbag over it as close to or on the centre column. The large leg is the load bearing leg and its holding all the weight. This is why you shot it and not the others. If its able to move then the stand can tip. This isn't a crane where the centre of gravity is high and needs to be counterbalanced. Always double shot if concerned about the weight because of postioning etc.
 
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