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Balancing the EFP

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#1 TobyBarraud



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Posted 21 June 2004 - 05:25 PM

I've been sneaking some posts in on the General site, but I know this question is pure Newbie...
I've read Holway's illuminating paper on dynamic balance, and have a basic understanding of what is involved. It seems essential to be able to adjust the distance of the battery and monitor from the post, but I have an EFP sled, and it doesn't seem to be very adjustable down there.
Am I missing something?
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#2 pbalsdon


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Posted 21 June 2004 - 06:22 PM

Not all rigs will allow you to do a "dynamic balance" which is what Jerry's paper is all about. A static balance is all you can achieve if you are unable to make adjustments to the below gimbal section of your rig.
Find the centre of gravity of your camera (with all accessories including film or tape attached). Mount the dovetail plate so it's centre is as close to that point as possible and mount the camera to the sled.
Put the rig on the spin side of your docking bracket and make sure the rig is bottom heavy by adjusting the gimbal up or down the post or lengthening the post. Move it to the upright position and adjust the dovetail position backwards forwards and sideways until the rig sits perfectly vertical. When you've achieved this tilt the rig to the horizontal position and allow it fall back to the vertical, this should take around three seconds. If it's quicker than that move the gimbal down the post or shorten the post, (if it's slower adjust the other way) and by trial and error find this three second "drop time".
If the drop time is too quick the rig will want lean off horizontal when cornering and then start to "pendulum" when instead of just correcting itself back to vertical. If the drop time is too long it will be more sensitive to errors from your hand while operating. The three second drop is a rule of thumb for beginners, as you become more experienced you can adjust this to suit your style and the requirements of the shot.
I used rent an EFP that had mod done, I think by Bob deRose, that allowed fore and aft adjustment of the battery bracket and also a CRT monitor fitted (Chroziel?). This rig had a great feel and was the first rig I could dynamically balance. It also had the capability to mount two batteries and carry a 35mm camera although I never tried that.
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#3 TobyBarraud



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Posted 21 June 2004 - 06:44 PM

Thanks for the low down, though it sounds like bad news: no dynamic balance for the EFP. I will nevertheless follow your intructions and at least have the rig static balanced with something like a 3 second drop time.
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#4 Ruben Sluijter

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Posted 21 June 2004 - 08:02 PM

There are some aftermarket toys available that will allow you to dynamically balance the EFP, I don't know if the DeRose mod is still available somehow but you might also want to try and as Howard Smith (MK-V) as he once made a great little battery mount as a custom job.
If you ask him nicely enough he might be persuaded to make another one.
You might even be able to do it yourself with a little tinkering, all you need to do is to seperate the battery part from the electronics part and allow it to slide in and out somehow (maybe with some rods).
The cable that goes from the battery to the electronics should allow for this and can otherwise be extended.

Being able to extend the battery far out is going to make a huge difference and make the EFP a great lil' rig for you.
It will make your shots much better to have both a static and dynamically balanced rig.
Good luck

Peace, Ruben "EFP: Extended Feels Proper" Sluijter
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#5 Howard J Smith

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Posted 24 June 2004 - 11:23 AM

Hi Ruben - chaps.

The other thing I did for Rubens EFP was to add one of our monitor arms (www.mk-v.com)
This allowed the monitor to be moved in and out as well.
If anyone is interested in this upgrade please email me
We can also upgrade the EFP sled to an MK-V very easily.

Hope this helps

Howard J Smith
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