Heavy Duty Backdrop CrossBar that doesn't Sag

[egproductions]

I bought a very large and heavy vinyl backdrop (10' x 25') and my current crossbar isn't cutting it. Because the crossbar sags in the center, you wind up with wrinkles in the vinyl on the sides. Can anyone recommend a crossbar that can handle the weight without sagging? Ideally it would be something that is still portable/collapsible.

 

[patrickbaldwin]

Or a third stand in the middle to take the sag out. Might be easier to lug than a thicker pipe. It's what I do on a 20x 20 silk that I use for stills.

 

[JPNola]

Consider this one:

https://www.bhphotovideo.com/c/product/183103-REG/Photek_S_4023_4_Locking_Background_Crossbar.html

No personal experience with it, but it looks pretty stout.

and another candidate:

https://www.bhphotovideo.com/c/prod...djustable_Background_Holder.html/prm/alsVwDtl

Speedrail is the way to do it right. Just not all that practice for travel or for keeping your kit compact.

http://www.filmtools.com/grip-and-electrical/rigging-equipment/speedrail/speed-rail-1-25.html

 

[Alpha Beta Omega]

I have a Manfrotto 272B and never noticed sagging with heavier loads.

 

[craftyphotons]

I also have a Manfrotto 272B which I'm currently using to support an uncut 86" seamless roll (which I believe is ~12lb). No sag for me!

 

[Bruce Watson]

I bought a very large and heavy vinyl backdrop (10' x 25') and my current crossbar isn't cutting it. Because the crossbar sags in the center, you wind up with wrinkles in the vinyl on the sides.

Welcome to the wonderful world of physics. You're in a gravity well, when you apply weight like this (evenly distributed), it results in a hyperbolic curve of the support beam. You can't eliminate it, all you can do is reduce it. Indeed, the curve is there even without the backdrop -- just the weight of the crossbar itself creates some amount of curve.

Sadly, anything you can use to remove the majority of the curve while clear spanning 25f is going to be pretty large.

The "easy" way out of this is to add a third support in the middle.

Can anyone recommend a crossbar that can handle the weight without sagging?

Even an I-beam is going to sag some (unless you build into it some reverse curve, the same way you would for the reinforcing I-beams in a concrete highway bridge, but I suspect this level of engineering is above what you're willing to pay for). If you are using a telescoping system, the joints are going to be your main problem as the slop in the joints will all be taken out by the weight of the bar/backdrop, and all in a direction that accentuates the perceived sag. That's just the laws of physics.

So again, the easy way out is to add a third support in the middle.

Alternatively, you could hang the backdrop from grommets every half a meter or so.

 

[David W. Jones]

The crossbars in my studio are from either Lowes or Home Depot, I can't remember which. Visit their pipe area. I purchased transportable length pipe which is threaded on the ends, and then used a connector to lengthen a pair for my green screen.