The mini beam splitter rig: portability for 3D documentary filmmakers

The mini beam splitter rig concept we came up with to film elements of our first 3D documentary has come to fruition.

We decided to try and build because the thought of moving and setting up our Film Factory 3D Indie BS Rig for one or two close ups is just too painful. Now we can use this smaller unit to shoot these components for the explosive demolition series Blowdown and save schlepping the full-sized rig around the Fonte Nova Stadium in Salvador, Brazil for when we’re shooting extensive B roll in one location.

The goal was to custom-design a rig that would house two Canon 7Ds and that was small enough and light enough to be operated by one person, handheld.

To achieve this, the mini beam splitter rig:

1) Has customized aluminum rails that aren’t as big and fat as the ones on the Film Factory Indie rig.

2) Is bolted and tweaked specifically for the dimensions of the Canon 7Ds.

3) Has a smaller box.

4) Is designed so the second camera is underslung – easier to handle because it’s not as top-heavy.

5) Allows us to get camera lenses closer to the mirror.

It was whipped up in a couple of days, and it’s not pretty – but it is portable and robust. We’ll see if it works.

Shooting a 3D documentary: Film Factory 3D Indie BS Rig mirror issues

So … we’ve broken the backup mirror we purchased for our Film Factory 3D Indie BS Rig to shoot our first 3D documentary.

This wouldn’t be a huge problem if the stock mirror that came with the rig were up to QC par.

But it isn’t – which is why we were using the backup in the first place.

Here’s the issue: one side of the stock mirror is coated and one side isn’t – the coated side is reflected to the camera that’s mounted on the top of the rig.

This disparity seems to cause a difference in light between the two cameras, to the order of one stop (ie. the upper camera gets about half the amount of light as the horizontal camera).

Our stereographer, Sean White, also found that there’s a slight colour difference between the two cameras, and a mild fogginess to the stock mirror.

We plan to use this rig to shoot the implosion of a condemned sports stadium in HD. And we deal with high-profile broadcasters – we have to deliver high-quality footage (for them and, more importantly, for a worldwide audience).

So Sean grabbed the spare – which we bought in case we break the original one while filming on an industrial site in Salvador, Brazil for the explosive demolition series Blowdown – to see if it gave us more consistent picture.

It did – there’s only 1/3 to 2/3 of a stop difference between the two cameras, the colour is almost matching, and it’s fog-free.

Though none of us are sure why this is the case, we moved to film with the superior mirror (ie. the backup became the starter).

But while Sean was re-screwing it into the rig, it cracked.

The placement process is quite a balancing act – screw the mirror in too loosely (or mess up the gaffer tape), and it threatens to slide out the bottom when you position it at 45 degree angle.

Sean thought he had found the sweet spot for tightening, but he was used to adjusting the stock mirror … the backup shattered under a similar amount of tension (which makes us think the first mirror may contain more plastic, but that’s just a theory).

Needless to say the setback is disappointing.

Sean got in touch with 3D Film Factory. They won’t exchange the stock mirror for one that’s like the backup. But they will sell us another backup at a deep discount.

Granted, this rig is cheaper than most of the other ones out there, so we can’t expect the moon.

But considering how integral a working mirror is to the system, hopefully quality discrepancies and the finicky screw-in process will be rectified in the future.

Shooting a 3D documentary: building a mini beam splitter rig for close ups

Vision alert. So we’re thinking of designing our own mini beam splitter rig to shoot close ups for our first 3D documentary . Here’s why: as I’ve mentioned,we’re trying to sort out our B cam system using Film Factory’s 3D Indie BS Rig – this should hopefully work for the majority of our B cam shots.

But it isn’t the most portable system – something that will surely prove challenging on an industrial site, where the explosive demolition series Blowdown takes place.

For the odd close up of the crew loading explosives etc. in a condemned sports stadium in Salvador, Brazil, it’s painful to think about moving the whole rig and setting up just to get a shot or two.

And we’d like to avoid using a side-by-side rig  because it’s a mission (if not a mission impossible) to get the cameras close enough together to film these types of shots.

If there’s a way to build a mini beam splitter unit, one person could just move in and get this footage with way less trouble (ie. instead of two people to set up the full-sized rig, etc.).

As an added bonus, we could also use this system in a temporary pinch if the main B cam system happened to go down.

We bought an extra mirror anyway, in case the one that came with the Film Factory Indie rig system malfunctions mid-shoot … why not try and put it to use?

Our stereographer, Sean White, knows a machinist who may be able to help us build this mini rig we’ve envisioned.

We’d probably use Canon Vixias – smaller than the Sony EX1/EX3 combination we’re trying to make work with the Film Factory Indie rig – and rig it as an underslung system.

One camera would be positioned below (instead of above), and the spare mirror would be angled the opposite way as the one on the full-fledged beam splitter rig.

This rig would theoretically snap onto a tripod, and would achieve a small enough interaxial distance for us to get the close-ups we need without a mega hassle.

If any stereo, etc. issues arose, we’d correct them in post – theoretically a relatively small workload considering we don’t use tons of these types of shots in our shows.

At the moment, it’s just an idea – but seems fittingly par for this unchartered course.

3D beam splitter rigs for Sony EXs: filmmakers weigh in

It seems we’re not alone in the quest to find a beam splitter rig/camera system that will work as our B cam setup for shooting our first 3D documentary.

My previous blog outlining the issue has been posted on the Yahoo! Group thread P+S Technik 3D Stereo Rig + 2 Sony EX3, where there are entries from several people looking for information on how to make this – and similar systems – work for them.

Here’s our particular issue: we’ve been testing a Sony EX1 and a Sony EX3 mounted on a Film Factory 3D Indie BS Rig, but are having issues getting the cameras optimally positioned.

One alternative mentioned in the Yahoo! thread is a P+S Technik rig, but from what I gather it’s more expensive than the Film Factory Indie unit we’ve purchased.

Another up-and-coming alternative seems to be Alister Chapman’s “Hurricane” beam splitter rig, evidently designed specifically with Sony EX3s in mind.

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3D documentary filmmaking: why Sony EXs aren’t ideal for our beam splitter rig

A week of testing our B cam beam splitter rig system has revealed that the Sony EX1/EX3 duo we’re using with the Film Factory 3D BS Indie Rig aren’t ideal for shooting our first 3D documentary.

The issue isn’t technical – Alister Chapman reports using the same cameras successfully, and we were able to genlock the EX3 to the EX1 by connecting the EX1’s Y channel of the component output to the EX3’s genlock in connector, just as he has.

It’s logistical …the cameras are just too big and cumbersome for this particular beam splitter rig.

We’ve modified the rig so they fit better, but getting them aligned vertically is rough – the mics protrude and we’re still seeing the edge of the box and/or the bottom of the mirror when we use our Sony EX 5.8 mm lens (which has a 56-degree horizontal angle of view).

Wide shots are a must for Blowdown, the explosive demolition documentary we’ll be filming, so we need a system that will effectively capture this kind of footage – ie. we need to hit the sweet spot on the mirror, have the cameras vertically aligned and not see the rig when we use wide-angle lenses.

The alternative is enlarging the image in post to eliminate the part(s) of the shot that contain the rig, but that will degrade the quality, so I want to try and avoid this (especially since we’ll be blowing the footage up it to a certain degree already to facilitate convergence).

So, now we’re working with Canon Canada directly to get loaners of the XF305, which has just been released.

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Shooting a 3D documentary: review – Film Factory 3D Beam Splitter Indie Rig

Our crew’s spent the last week testing the B cam system we hope to use to shoot our first 3D documentary.

Here’s what we’ve learned about the Film Factory 3D BS Indie Rig:

Pros

1) Relatively affordable: rings in at $3,895 US plus shipping and handling (we also bought an extra mirror in case the first one smashes in the field. Don’t think we’ll find a second lying around at the condemned sports stadium slated for explosive demolition in Salvador, Brazil, where we’re going to be filming, and shipping one in would surely be a nightmare).

2) Robust but adjustable: the rig’s sturdy, so I think it will stand up well in the field. But luckily the structure isn’t rigid – we’ve had some difficulty lining our Sony EX1 and EX3 up properly (see: large and cumbersome … it’s a problem), so we’ve disassembled the rig, manually repositioned parts, and tightened them to try and accommodate the cameras.

Specifically, the aluminum rails are locked in with screws that can be loosened, adjusted, and locked back in. Without this flexibility we’d have no hope of effectively adjusting the heights of the cameras relative to the base rail (which we’re still working on. Argh).

Cons

1) Manual operation: It doesn’t have all the fine, automated controls that the higher-end feature film rigs do. It lacks motorized components, so factors such as interaxial distance and convergence have to be adjusted manually. In feature film production, it’s often one person’s job just to operate the remote to make these adjustments on automated units.

2) Heavy load: This is just something the crew’s going to have to get used to – 3D shooting demands so much more gear. But it’s still a downer. Total tally: the rig, a tripod, two mid-sized cameras, the nano3D recorder, the Transvideo Cineform 3D Monitor, all the sync cables, and battery. We think it may take two extra bodies in the field just to move all of these components around.

And the cameras are a whole other story … more to come on the Sony EX1/EX3 issue.