3d Alexa Fun

[Alec Jarnagin SOC]

In addition to the stress on the operator, arm, and gimbal, these rigs have to put massive leverage and weight on the top stage. I wonder how the specs work out?

[Kevin Packer]

A friend of mine works at 3DCC here in Toronto and they seem to be innovating a lot of lightweight setups. Their newest one called the Hawk Eye is basically 2 SI2K's mounted in one box completely fixed and pre-aligned. So as long as the subject stays a min of 6 feet from the lens all is good and everything is in focus and they'll converge and adjust in post. Best part the whole thing is 10 pounds or less. It's definitely more geared toward documentary or TV run and gun style but it's still nice to know not all 3d is heavy as f***. I tested it out on my rig with this nice new touchscreen monitor/recorder deck right before they went to New York for a mock concert shoot. I was never told who the operators were but maybe they could chime in on how it went?

[Thomas English]

That leverage on the top stage also massively concerns me. Generally you have so much shear weight pulling so many things in the wrong direction. You definately worry for your kit. Whats also so tricky is that tiny distance between the front of the gimble and the back of the upwards pointing camera. Controlling that gimble is so it doesn't bump that camera is hard at first.

 

I know one camera is pointing upwards and its CG is below the Gimble but I still don't get how short Larry's post is. I've only worked with 2 REDs on similar dimmensions and my post is never that short. The Alexa's must be more rear heavy than the REDS.

 

Its noted that he is carrying a battery on the back of the top camera. This has helped shorten the distance of the bottom 3 batteries away from the centre post. That distance being too long is a nightmare on hard mounting systems

[Pedro Guimaraes SOC]

In a recent conversation with him, weight had less to do with his concerns than the problems associated with convergence adjustments and its effect on quality steadicam operating.

 

 

He's probably referring to IO adjustments not convergence. Convergence cange doesn't affect balance too drastically as one camera is just toe-in. Usually when you change IO the balance changes and it can affect your horizon.

 

Even with a well balanced p+s rig with counter moving cameras you still can get a change in horizon.

 

Besides, 90% of what I shoot we shoot "parallel" and converge in post. The only reason to really converge on set or in-camera is for LIVE broadcast work. Most of the time there are many advantages to leaving convergence for post.

[Alec Jarnagin SOC]

Kevin,

 

My wife ended up DPing that New York gig. I was not available but the two operators were Aaron Medick and Nicolas Doldinger. I know Aaron pokes his head in here now and again and has a few pictures.

[John Buzz Moyer]

He's probably referring to IO adjustments not convergence. Convergence cange doesn't affect balance too drastically as one camera is just toe-in. Usually when you change IO the balance changes and it can affect your horizon.

 

Even with a well balanced p+s rig with counter moving cameras you still can get a change in horizon.

 

Besides, 90% of what I shoot we shoot "parallel" and converge in post. The only reason to really converge on set or in-camera is for LIVE broadcast work. Most of the time there are many advantages to leaving convergence for post.

.

 

On the pace system, convergence is the most significant balance affecting attribute. It most definitely will change the balance of the rig... during a shot.

Edited July 27, 2010 by John Buzz Moyer

[Michael Tsimperopoulos SOC]

On the pace system, convergence is the most significant balance affecting attribute. It most definitely will change the balance of the rig... during a shot.

 

Hi, I am a little confused. I thought that Pace solved this issue three years ago...

 

From David Emmerich's interview in SOC magazine (spring issue) regarding "Avatar":

 

"Jim (Cameron) saw me struggling to keep the Steadicam under control during moves where the IO and convergence shifted, and told the guys at Pace Camera to come up with a solution. The president of the company, Patrick Campbell, came through with flying colors. He built and programmed a slick motorized plate that slid the whole bottom portion of the sled side to side to counter what the camera did on the other end. He installed it the day I had some fairly big Steadicam shots to do and it worked perfectly on the first try. It’s no exaggeration to say it saved my ass. Jim looked at what I was able to do and said something along the lines of, “So this is how you shoot when you’re not blindfolded with one arm tied behind your back.” After that we shot a signifi cant amount of the live action with the Steadicam and life was good."

 

I don't know... Is it the only system that auto-compensates ? Am I misreading something ?

[Pedro Guimaraes SOC]

Most systems I have heard about that have counter weighting built in only do so for IO changes. This would include p+s Freestyle, ScreenPlane and the upcoming 3ality "steadicam rig the ts-4.

 

I know pace is toe'in in both cameras for convergence instead of just one. So maybe it's also like this in the "steadicam" version.

 

The problem is because of front heavyness, we tend to put accessories and maybe even a battery on the horizontal camera (as evidenced by Larry's above pic) This would mean that the rig would go out of balance when adjusted because the weights of each end of the beamsplitter are different. This would be the same effect for IO and convergence adjustment on the pace rig since the weight is clearly different on both cameras.

 

This is exactly what I experienced on the p+s rig.

 

 

For reference,

 

IO or IA (change in camera distance) will always be the biggest factor in affecting our steadicam balance. Since the cameras can change positions anywhere from .5" apart to 4" apart during a shot.

 

Convergence (1 camera or both rotating inwards) will always affect less since the camera position is not moving. The camera is just rotating inwards. I when I say rotating I mean very little! milimeters. This adjustment even tough minimal will definatly affect balance but not as much as a change in camera position.

Edited July 27, 2010 by Pedro_Guimaraes

[John Buzz Moyer]

Okay... Yes, Pace did solve the problem by having a sliding attachment integrated into the bottom of the sled. Basically, as the "convergence" changes during the shot, the bottom assembly counters the weight change from the camera moving on top. There were times during a lock off, and the convergence puller adjusted convergence, the camera would be affected by that motion. If the talent moved from a distance closer to camera, I could feel the motors working to counter balance the system. It was just enough to wiggle the horizon ever so slightly. In my experience, our stereographer and DP would set the IO per shot and leave it... the convergence, like focus, would change based on the action of the talent in the frame. We were lucky to have a dailies trailer to check the choices every day to verify the work. Yes the IO is the adjustment with most horizontal movement, But, as stated it was set per shot and the convergence change was the only adjustment affecting balance.

 

The film comes out next month by the way...

[dave]

looks heavy