GPI ARM

[Alexandre Lucena]

I have learnt it is possible to combine light, medium and strong springs in the GPI arm to accomodate

different camera set ups. Cool. How are they placed as to obtain the optimum tension? for

instance are they placed in cross section or two in each section, the front and the rear .

 

Thanks

 

Alexandre

[Michael Stumpf]

I have learnt it is possible to combine light, medium and strong springs in the GPI arm to accomodate

different camera set ups. Cool. How are they placed as to obtain the optimum tension? for

instance are they placed in cross section or two in each section, the front and the rear .

 

Thanks

 

Alexandre

 

Well, there aren't "medium" springs.

There are light (blue tip colored) and heavy (black tip colored).

 

And you criss cross them in each section...meaning if you put the heavy spring in the top of

the section closest to the socket block, you put the heavy spring in the bottom of the section closest

to the post.

85% of the time you need one light and one heavy in each section

of the arm and that takes care of most 35 mm film cameras.

[Charles Papert]

I may be remembering this wrong, but I think that the only reason to alternate the heavy and light canisters in the way you describe, Michael, was simply to make the socket for spring adjustment more accessible to the wrench (both in the middle)? i.e. it's not a performance based necessity--the arm will respond the same regardless of which type of canister is on top or bottom.

[Alexandre Lucena]

Thank you Michael and Charles for claryfing.

 

I have recentely custom built an arm and I am willing to accomodate cameras like the

HVX 200 and heavier ones such as Betacams and lighter 35mm. From my tests so far

the cross section would allow for the two light springs to be tensioned

slightly and the heavier springs were disabled which suficed for a DVX 100 with the aid of a

heavier camera plate adapter made of steel instead of alu.

[Alec Jarnagin SOC]

"From my tests so far

the cross section would allow for the two light springs to be tensioned

slightly and the heavier springs were disabled "

 

Not sure what you mean by this. The only way to "disable" the springs is to remove them! The PRO arm only needs one spring per section to function. As for canister placement, it makes no difference - it is simple preference as to which canisters you want to be able to adjust while wearing the rig. Hell, you could even put two heavies in one section and two lights in the other and be able to fly certain cameras, but obviously you'd never do this because it would be hard to wrap your brain around regarding where to place the tensions.

[Alexandre Lucena]

Alec

 

The arm that I built uses extension springs. I unscrew all the way the ones I do not need to use.

They are not placed in canisters.

 

 

Alexandre

[Alec Jarnagin SOC]

Alexandre,

 

Sorry, don't know how I missed that part of your post! Thought you were using a PRO arm.

 

Enjoy your new arm.