GH1 Stereoscopic Rig Collaboration

... actually, what made you decide to place the 2nd body at the bottom? Is it to avoid reflections? I'm just thinking that if placed at the top (and with the whole rig lowered), you could use its LCD to frame the shot. Of course you'd then be literally 'shooting from the hip' :).
 
g.l said:
So it's attached to some kind of belt? How heavy is it to wear?
Click to expand...

I built a harness from a fireman's respirator pack. It works really well - transfers the weight to your torso evenly. It's not vibration dampened, however. I have a a spring-arm steadycam that I'm modifying for this purpose.

The all-up weight with light is 16 lbs.
 
g.l said:
... actually, what made you decide to place the 2nd body at the bottom? .
Click to expand...

It's a simpler, more stable mount with one camera underslung. Also makes the rig top a convenient place for lights. The basic beamsplitter is a prototype Aquavideo Aero - which we're now using for a LOT of projects. Absolutely the most square rig I've ever used - and will be very affordable when it's released for retail.
 
g.l said:
... actually, what made you decide to place the 2nd body at the bottom?
Click to expand...

Haven't you seen my rig (there is a picture somewhere in this thread)? I've decided for bottom placement because of several advantages over the top placement (brightness of the sky, sun reflections, dust, ...). It works really good. It has been used on one commercial and the footage is excellent. The only problem is polarisation.
 
Last edited:
crunchy said:
The only problem is polarisation.
Click to expand...

I've experimented with 1/4 wave retarding film from this company.... http://www.apioptics.com/quarter-wave-retarders.html

This is very useful when shooting near water, where the polarization disparity can be really untenable. If you follow the CML-3D discussions on the topic (http://www.cinematography.net) you'll find some helpful tips on using 1/4 wave retarders in front of the beamsplitter. The problem that I'm having is that, with long lenses, the optical quality of the filters, beamsplitter glass and retarder film becomes an issue. With wide lenses - not so much of an issue.
 
David Cole said:
If you follow the CML-3D discussions on the topic (http://www.cinematography.net) you'll find some helpful tips on using 1/4 wave retarders in front of the beamsplitter. The problem that I'm having is that, with long lenses, the optical quality of the filters, beamsplitter glass and retarder film becomes an issue. With wide lenses - not so much of an issue.
Click to expand...

I followed that discussion. However, I am quite reluctant to add some glass/plastics in light path. It's a pity that you cannot solve such problems easily.
Concerning problems with CPL (circular polariser), I discovered that everything is fine and I've made a mistake, so I deleted part of my previous message.
 
Any idea how to make a Y-cable or modify one of these microcontroller-driven remote shutters to operate 2 cameras?
Would be great to do 3d time-lapse.
(They all run GND through 3 metal-strips first shorten one, then both resistors. So I can't just drop in a double-switch after opening the case.)
 
Marcus:

As you have noted, you can't simply Y the shutter release cable - as the camera uses variable resistance to determine which button has been pressed. You can cobble together a circuit to switch the resistors onto the remote lines fairly easily - or - you can use a wireless intervalometer controller with two receivers (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150640017160#ht_2025wt_1165).

Something to consider... the GH1s and 2's poll the remote lines to sense the resistance values. As the polling begins when the camera boots up and each camera will boot up independently, the shutters may not release precisely in sync. To minimize this issue you can power the cameras up simultaneously. The simple circuit to do so is posted earlier in this thread.
 
Last edited:
So they sense the presence of a remote shutter at boot and I can't switch to an external microphone later without powering off the cameras?
(Well okay. Maybe just open up the camera again and see if I can separate these two functions at a later time.
I already took one apart and put it back together again because I fried that microscopic polarity-safety diode on the power supply because
some Chinese switched the meaning of red and black in their Canon 450D battery-grip.)

The wireless ones seem to cost a fortune and I can't buy the receivers separately.
That circuit was what I was asking about.
I can't switch a relay if there's just a change in resistance on the first camera.
The drop from 2.5V to 1.0 and 0.5V with just a few mA for sensing doesn't quite lend itself well to switch anything simple reliably either.
No idea yet.
 
RE: External Mic.... seems like remote operation and external audio are mutually exclusive.

RE: Circuit... it's pretty simple to build a simple timer circuit (555 timer IC) that drives two solid state switches to switch the resistor values onto the remote line, if you don't want to drop the coin on the wireless remotes.
 
David Cole said:
RE: External Mic.... seems like remote operation and external audio are mutually exclusive.
Click to expand...

Yes, if you don't open the camera and start soldering inside it seems that way.
I'll have a close look at that circuit when I return from CCCamp.
Here are some photos (click the "photos" -link) from when I took it apart the first time...
http://marcuswolschon.blogspot.com/2011/07/taking-apart-camera.html
All you need is a PH0 screwdriver, some pliers to apply enough force to the screwdriver and some patience.
The board on the left side looks simple enough. And there even seems to be some space left to just maybe insert a separate connector for a remote shutter to leave the original one for sound.
(I'll upload higher resolution photos soon. Just recently found out that Google+ -users can upload 2048x2048 instead of the usual 800x800 with no disk-space-limitation.)

RE: Circuit... it's pretty simple to build a simple timer circuit (555 timer IC) that drives two solid state switches to switch the resistor values onto the remote line, if you don't want to drop the coin on the wireless remotes.
Click to expand...

That timer would mean I need a display and a microcontroller and buttons and a power supply and a tested and working program,.... I somehow have to set intervall, initial delay, number of photos to take and exposure-time.
That's exactly the part I wanted to avoid. ;)
 
Remote and audio can be switched, but not during recording - so if you use the remote to record, you cannot use an exernal mic until you stop. It's possible a firmware hack might defeat that at some point.

EDIT: to clarify, on the GH2 at least it looks like this is only a firmware limitation. I tested with remote and mic wired up, and the firmware won't play ball.

BTW, I bought the cheapest 46mm faders I could find, and lucked out on them - they do NOT act like pola filters, as they are configured circular/linear (front/back), so they're infinitely more suited to dual-body 3D. The downside is that they produce a slight colour cast from blue to yellow as you rotate them (the entire filter, the fading itself doesn't produce a cast). Anyway the casts are taken care of by auto/manual white balance, and the filters are ultra-thin, so I'm very pleased.
 
Last edited:
MarcusWolschon said:
That timer would mean I need a display and a microcontroller and buttons and a power supply and a tested and working program,.... I somehow have to set intervall, initial delay, number of photos to take and exposure-time.
That's exactly the part I wanted to avoid. ;)
Click to expand...

That was exactly my concern, until I read about a simple approach that just measures the interval between two shutter activations, and then continues shooting using it. That's what I ended up implementing in my circuit - the only user interface is a switch which powers the microprocessor that monitors the next two focus/shutter activations and then fires away. It will only be as accurate as you can trigger it in real-time, but it works for me.
 
GH2 Rig up and running

GH2 Rig up and running

I'm having great results with my GH2 rig.


I'm so happy with the motion coding in the latest series of patches for the GH2 (especially Driftwood's GOP3 132M AQ2) that I'm not looking back to the GH1 for visible-light use. I'm sending my last set of GH1s for full-spectrum sensitivity modification. By the way - this is straight out of the rig without color correction - you can see the tint from the beamsplitter mirror reflection side.
 
As per above, I've been doing quite a bit of work with full-spectrum shooting in 3D. One of my rigs uses 2 GH1s with the sensor stack modified for full-spectrum sensitivity. Here's a little sample:

 
Now that some of you seem to have working 3D rigs - what are you guys using for monitoring when aligning the rig and shooting? Are there monitors or 3D multiplexers that have HDMI inputs, and not prohibitively expensive? I'm looking at the AJA Hi5 3D, but that needs HD SDI on the inputs. Any advice?
 
I started building my own StereoMirror type monitor (2 HDMI panels, with a beamsplitter to overlay the images), using custom 5.6" panels & LCD controllers. It's note quite complete, I found that I don't desperately need it the way I shoot lately so I haven't finished it yet. But it will definitely come in handy with the up-to 10m camera separation hypers I plan on shooting.

Apart from stereo previewing, I'm also looking forward to just having a 720p view of what I'm shooting. The low-res LCD screens on the cameras really don't show you enough detail to gauge a shot. Yes you can focus with the focus-assist blowup, but then the shot is heavily cropped and you still can't see how your DOF falls over the rest of the frame.
 
Thanks for your reply, g.l. But I address the monitoring question again, since I shoot with a mirror rig (the Genus Hurricane Rig) and need to align the cameras correctly - a difference view from both cameras would be most helpful. Maybe David Cole can chime in on this? David, what do you use for monitoring when aligning and shooting 3D with your rig?
 
Sync demo.

Sync demo.

Just a quick demo to show that a simul-powered GH2 dual rig is capable of excellent sync. This is a crop from my GH2-3DD, 1080 60i take, 3mins in:

_gl%27s%20GH2-3DD%20sync%20demo.gif
 
Last edited:
You must log in or register to reply here.
Back
Top