Sony EX1/EX3 Mirror rig DYI
 

Hi all...

I've been building a mirror rig using My Sony EX1 and Convergent Design's EX3, for the purpose of testing and product feedback for the nano3D. We first put together a side-by-side rig, shot some real world projects, and quickly learned the limitations in terms of I.A. and stereo space compared to a mirror rig.

I thought I'd share some of the process, both in design and construction, for all that are interested. Not everyone will want to build their own rig, but it's an interesting process and quite a learning tool for the stereographer in training.

The first step was to determine the major components and parameters;

1.) Zero I.A. up to about 5" of I.A. at full wide angle (64.7 degrees Horizontal FOV) on the EX zooms was important. This determined the size and shape of the mirror and in fact, the whole rig.

2.) I also wanted the I.A. to be evenly split between the cameras, centered over the tripod pan. Most rigs just move one camera, so any pan tends to occur under one eye, with the other eye pivoting around that point. Not very natural, IMO.

3.) I also wanted an "over" rig, with the second camera shooting down. This allows for tripod tilts and jib operations easier than the "under" rig style. Of course CMOS skew needs to be accounted for, and that means that the over camera is orientated so that the tripod base faces out from the rig.

Nothing beats the real thing, so before heading into the computer to design the rig, I mocked up the cameras in real space to get a feel for the volume and see what issues I might face. Here are some alignment tests during the design process;

http://ftp.datausa.com/imageshoppe/i...EX3_rig_01.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_03.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_08.jpg

As an aid to alignment, I built some foam core lens hood extenders that allowed optical axis placement and a visual check for alignment, as you can see in the photos. Since then, I learned that there's an actual PL mount tool similar to this, that you can use on "real" cameras... nice.

More to come...

Regards,

Jim Arthurs

Rig design and materials
 

Next in the process was selection of materials. I'd seen pictures of the 3D Film Factory rigs...

3D CAMERA RIGS

...and noticed that they were built, for the most part, with components from the 80/20 company...

80/20® Inc. - The Industrial Erector Set�

So, why re-invent the wheel? I did take a number of design changes, where I thought the Film Factory rig was lacking, beefing up the main assembly and allowing for my dual camera I.A. adjustment.

While the side-by-side rig I built for Convergent Design had toe-in, here on the mirror rig I made the command design to keep everything parallel, and rely on the nano3D's ability to preview horizontal adjustments. Since the nano3D also allows for image flip and flop, can preview anaglyph, you can pretty much eliminate all the billions of black boxes needed to preview your stereo in the field.

In my 3D program of choice, Lightwave, I designed the rig and created a cut and part list for the 80/20 materials...

http://ftp.datausa.com/imageshoppe/i...X3_layout4.jpg

Navigating the 80//20 catalog and creating an order is a bit like learning a new language, but soon I had a nice package of materials on my workbench, all cut and tapped, ready for assembly...

http://ftp.datausa.com/imageshoppe/i...ror_rig_01.jpg

While it would take some time to get everything really put together, within an hour I was looking at this...

http://ftp.datausa.com/imageshoppe/i...ror_rig_03.jpg

More to come....

Jim Arthurs

camera attachment and stability
 

The big problem with the Sony EX1/EX3 is the tripod screw area... it's horrible. The entire bulk of the camera depends on a tiny metal plate less than 1.25" by 1", held to the bottom of the camera by 4 tiny screws. On top of that, the bottoms of the cameras are curved and non-planar, an attachment nightmare.

There are third party options, various base plates and the like, but I wanted something better, something actually registered so that you could remove and return the cameras to the mounts and not have to re-align.

The solution that came to mind was to take a pair of Bogen 357 release adapters and modify the camera plates with a custom molded base. This was going to be a world of hurt in terms of effort and time, but I felt it would pay-off.

So, step one; pull RTV silicon molds from the bottoms of each camera.

http://ftp.datausa.com/imageshoppe/i...EX3_rig_04.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_05.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_02.jpg

Next, pull male copies from the molds, using a mineral filled urethane plastic..

http://ftp.datausa.com/imageshoppe/i...EX3_rig_09.jpg

I then filled in all the tiny details and screw recesses on the males, creating a smooth "plug" for casting the final camera seats.

Next I machined up some aluminum riser plates to compensate for the different optical axis heights between the two cameras;

http://ftp.datausa.com/imageshoppe/i...EX3_rig_12.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_10.jpg

Now I was ready to cast the custom seats in plastic right onto the modified plates/risers...

http://ftp.datausa.com/imageshoppe/i...EX3_rig_13.jpg

Giving me these...

http://ftp.datausa.com/imageshoppe/i...EX3_rig_14.jpg

After they are sanded down, and all the areas where buttons on the cameras might be covered are revealed, they will be ready to work. A completely custom solution with precise registration.

Oh, did I mention that the EX3 actually tilted DOWN a couple degrees in normal mounting, and wasn't perfectly perpendicular? I had to compensate for that in the mount as well with a few shims under the riser... good times...

More to come...

Jim Arthurs

The Mirror Frame
 

Next up is the mirror and mirror frame assembly. My mirror needed to be 10" by 18.5" to accommodate the full wide angle of the EX1/EX3 stock lens, and allow about 5" of I.A.

I got the 50/50 mirror from these folks;

Stereoscopic Mirror Manufacturing

Custom cut, it was about $210 US... I don't want to break it! I will be using a piece of plexi as a stand-in until the rig is finished. And yes, the upper camera will have a fail safe to keep it from sliding down and crashing into the mirror.

I puzzled over the mirror mounting for some time. I didn't want any stress on the mirror, and I wanted it supported as much as possible. I took aluminum channel guide designed to fit around 1/4" thick panels and bent a three sided frame out of it, with the corners re-enforced with gussets.

http://ftp.datausa.com/imageshoppe/i...EX3_rig_16.jpg

The inside of the channel will be lined with 1/16" sponge neoprene on all three surfaces to cushion the glass. Did I mention I don't want to break it?

To mount the frame to the rig, I'm machining some attachment posts that will allow the frame to be adjusted up or down, and will add some rigidity to the assembly. Here's one in progress on the mill...

http://ftp.datausa.com/imageshoppe/i...EX3_rig_17.jpg

More to come...

Jim Arthurs

Thank you
 

Thank you Jim! Please keep posting
Cheers

Great Posts!

We have been using a 3D Film Factory Rig for the last 4-5 months, so its fascinating to see this approach.
Thanks Jim,

Bwe

Camera saddles part 2...
 

Hi all... finished the fitting and sanding of the camera saddles and did all the necessary opening up of areas for access to all controls and ports. Used my big 10" disk sander and a dremel tool for the close work. I still need some fine sanding and some spot putty, maybe a paint job.

http://ftp.datausa.com/imageshoppe/i...EX3_rig_18.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_19.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_20.jpg

This was the moment of truth on quite a series of steps and labor that I outlined earlier. Wow, this WORKS. Absolutely no play in the cameras, so solid and rigid that it's a bit scary. Perfect registration, and I feel comfortable removing the cameras and putting them back and not having to worry about a re-alignment.

Some manufacturer needs to get on mass producing this sort of cradle/saddle for the EX1 and the EX3. I know I'll use them for my normal day to day tripod operations as well.

More to come...

Jim Arthurs

The mirror frame, part 2
 

Okay, I've got the mirror frame finished, save for the neoprene. I did have to make a second mirror frame, as my first one was about .25" too wide. Operator error, measure twice, cut once, etc.

The pivot supports turned out great, no chance of stressing the mirror and they tighten down real well... plenty of adjustment, the frame can be moved independently on the supports up or down, the support mounts can be moved forward or back, and shimmed higher if necessary.

http://ftp.datausa.com/imageshoppe/i...EX3_rig_21.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_22.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_23.jpg

As an overview, here's the rig at the moment, I just need to finish the camera platforms (the EX3 platform is finished) and I'll be ready to give it a go.

http://ftp.datausa.com/imageshoppe/i...EX3_rig_24.jpg
http://ftp.datausa.com/imageshoppe/i...EX3_rig_25.jpg

Oh, I still need to find the balance point for the tripod mount, but I'll wait until I can load up the rig with the cameras and all accessories before doing that.

I'm ordering up some more small items for the finish. Boy, these pictures remind me I need to do a full workshop clean-up soon!

More to come...

Jim Arthurs

Thanks everyone for the feedback on and off the forum!

Hi Bwe, I'd love to hear about your experience with the Film Factory Rig, and any comments you might have on what works well, and what doesn't. I'm sure I'm doing things differently in certain areas, and it's never too late to change things!

One thing I would be interested in knowing is if you're able to shoot at more than one focal length, or how difficult it is to re-adjust if you do change zoom.

I'm optimizing my rig for the EX1/EX3 combo, but I'm pretty sure a couple of RED's could fit on it as well with just a swap out of the camera support posts.

I do now have a great appreciation for folks that want to manufacture a rig, it's no small undertaking, and something I would never want to do.

Regards,

Jim Arthurs

Jim,

You are having way too much fun! The cradles look great, when can I get a pair?

Have you seen these for alignment: adjustable instrument & camera mount: Huber Industries I'm thinking about some uProcessor driven stepper motors to drive the screws.

Brian

Well funnily enough I have been using the EX1/EX3 combo aswell, and for the most part it is working well now. Initially it was alot of work to figure out the best way to put it together.

We have the Indie rig, and the first thing we realised was that we couldn't have the ex3 as the (top,left,moving) camera. It was just a bit too heavy for the mount so it wouldn't sit at 90 degrees, im sure with some stronger mounts it would be ok, I just havent taken the next step yet.

Then to squeeze the cameras into the rig so they could line up we pulled off a few of the crossbars, the handle/controls of the cameras initially would just overlap.

http://www.naluproductions.com/downloads/indie_rig.jpg

Apologies im not the well versed on the materials/building side of things.

Before any shoot I use a laser level to align everything, while monitoring the picture on a laptop.

http://www.naluproductions.com/downl...ie_laser01.jpg
http://www.naluproductions.com/downl...ie_laser02.jpg

Its usually right to go from then on, changing focal length is a bit of a pain, but just having a checklist of things to run through each time helps. We actually plan alot of shots either full wide or full zoom, and have those two positions marked out on the rig so it can quickly be lined up. Don't have a zoom system yet (asking santa for that one), and sticking to shooting parallel so any small adjustments/cropping I do in post, which is inevitable anyway.

Love your mounts and the position of the lower camera on your rig, just having the ability to move both cameras horizontally is something I really wish we had. Also having just one point to move pieces would be great.

eg. one spot to move mirror forward/back, one spot to raise the left camera up and down, rather than 4-8 screws each time :)

Bit long winded, apologies. Any specific questions let me know :)
Big grats on the rig too, its looking great.

Brendan

The use of the laser level is interesting. That it gives you a cross hatch pattern is really nice. Can you share where one obtains this laser tool?

The laser is a GREAT idea, THANKS Bwe, and it gave me an idea to do something similar... I've got a shop laser that I'm mounting to fit the front of the mirror box so that it's an all in one solution with registration to the rig... That way you just clip it on the front, and you can align without having to set up an external unit.

Here's the laser I'm using, it has a precise shaft and can fit into a jig with good registration...

LittleMachineShop.com - Edge and Center Finder, Laser 3/8" Shank

Regards,

Jim Arthurs

Not being a wood worker or machine shop guy I'm somewhat confused by your terminology here. Does this laser unit that you've linked to provide the cross-hatch type of pattern we see in the above photos? Where are you mounting it to obtain a perfect centered spot?

Hi Bruce, this video should explain the function of the laser in the shop...

Laser Center/Edge Finder In Action

It doesn't make a cross-hatch pattern, just a fine dot. It would be mounted at lens center on a support at the front of the mirror box, dead center (adjustable up or down). I would then put paper cross-hair patterns on the lens fronts and align from there... I'll post pictures when I get to that point to make it more clear...

Jim A.