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Different cameras for stereo compositing with a 3D rig
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Author:  wodendigital [ 20 Oct 2013, 18:23 ]
Post subject:  Different cameras for stereo compositing with a 3D rig

Hello all. I am researching for a project I am doing next year.

To keep it brief and to the point I want to use a stereo rig in order to composite the image from a modified camera over the top of my normal shooting image. Camera A is a Blackmagic Cinema camera, but due to the nature of the camera I can't modify it In the way that I need to. So we are looking into modifying a hacked GH2.

—There would be no interaxial separation. I would simply be overlaying the two images, masking out the areas I want shown by the modified camera in post.

—Neither cameras have Genlock so I would have to LANC the two together, but I realise there will be shutter drift very quickly.

—Whilst both cameras are m4/3 mount the GH2 has a slightly larger sensor. This will affect my field of view obviously, but not my depth of field. Technically all I am doing is using more of the image circle by a crop factor of 0.3. Same lenses will be used on both cameras.

—The modified camera image will look very different to the standard camera

—I am at no point utilising the whole frame with the modified camera. Only the areas I am masking out in post.

So I am desperately looking for opinions on what potential issues I might have and whether this experiment will work with the option I detailed above. I don't really want to shoot with two GH2 fir these shots but if this is the only way to do it I may have to.

Thanks for your time.


Author:  nosys70 [ 21 Oct 2013, 11:39 ]
Post subject:  Re: Different cameras for stereo compositing with a 3D rig

all that is pretty useless if you cannot make sure the picture will match.
even if you use same camera and same lens, there will be small discrepancies to correct.
I do not really understand your project, if you use a rig with overlapping pictures, you basically
have twice the same picture. I do not see what effect you can bring to the 2nd picture that cannot be done in post.

Author:  wodendigital [ 21 Oct 2013, 15:59 ]
Post subject:  Re: Different cameras for stereo compositing with a 3D rig

The GH2 will be modified for infrared. You can fake a general IR 'look' but it is impossible to recreate what i am trying to do, in post.

Only parts of the frame will be visible from the modified camera, as it will be masked out in a composite.

When you say discrepancies are you talking about shutter lock or field of view/image size. Shutter lock I'm concerned about, field of view not so much, considering my subject and what I'm shooting.

Unfortunately I have to be vague.


Author:  Dregolan [ 21 Dec 2013, 15:23 ]
Post subject:  Re: Different cameras for stereo compositing with a 3D rig

Hey, I'm trying the same thing but with two gh1s (all I have at the moment) have you run some tests yet? I still have to convert for IR but I'd love to see what's comes out when overlaying IR with normal video. Can you post/pm me any results if you get them? One other idea I can't afford right now but I think would be cool is two 5ds with magic bullet running hdr for both the IR and normal camera, now that would be a hell of a thing!

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