GH4 Balancing Gh4 & Devin Graham Glidecam

[Ben01]

Hi all,

I have a gh4 with lumix 12-35mm f2.8 and have recently acquired a Devin Graham Glidecam but am having a few issues stabilising it properly.

Obviously these things were designed for much heavier cameras (although the minimum weight spec says 900grams) but im hoping to find some folks who've managed to perfectly set it up despite its light weight.

The general consensus seems to be to put two counter weights each side on the base (4 total) and leave the fins fully in (not extended). That automatically makes the base very heavy. Apart from the camera and lens (about 865grams) I have also added an ND filter, a different quick release plate on top of the included quick release (to match my tripod for easy changing) and 1 counter weight. I estimate the top weight to be about 1100 - 1200grams and I'm using a drop time of about 2.5 seconds.

I seem to be able to balance it okay statically - standing still it stays level and doesn't sway - but am having great difficulty achieving what is termed "dynamic balance" - I.e when you walk and come to a sudden stop the Glidecam should also come to a complete stop and not keep going by rolling forward or back. This seems to be the biggest problem for me and I'm hoping some folks on here might be able to give some advise ???

Many thanks 

 

[Imamacuser]

Here's a tutorial on how achieve dynamic balance, it's a different stabilizer but the principles apply.

 

[CharlesPapert]

What you are describing has nothing to do with dynamic balance, but that's OK--that term is easily misunderstood.

The nature of having a slightly bottom heavy rig (2.5 seconds drop time) is that it is something of a pendulum. When you come to a sudden stop, the bottom of the rig will have more inertia than the top and "want" to keep going, which causes the pendulum issue you described. This is perfectly normal. As an operator, you actually have to apply a TINY bit of counterforce to the post to prevent this from happening. It's like a little tap, like pressing a button and letting go, you don't want to grab and hold. If you are coming to a stop, you want to apply that stop to the front of the post, under the gimbal...if starting from dead stop, you apply to the back of the post. There are many tutorials online to discuss this type of thing.

As an experiment to prove why this is happening, try making your rig neutral i.e. infinite drop time and doing the same test. Without any bottom weighting it will sort of float around aimlessly, but you should see that coming to a stop doesn't make it kick out at the bottom as you've experienced. Without that bottom heaviness, it's tough to get the system to "behave" and you are constantly guiding it to level rather than it finding its own level, so you make it a little bottom heavy and then manage the forces that result from this.

Learning how to control the rig during acceleration and deceleration is one of the standard skills that any gimballed stabilizer owner must learn. It takes a while so don't get frustrated!

"Dynamic balance" refers to the way that the various masses are distributed around the rig and how they affect the rotational attitude of the system. If for example you had three weights at the front of the sled and one in the back, you could get the rig to statically balance again by sliding the camera backwards. But if you did a fast pan, you'd find that the nose of the camera would always dip down mid-pan. In the case of a simple co-planar lower mass such as your Glidecam, as long as the bottom is built symetrically from front to back and side to side, you should never have problems with dynamic balance with your rig.