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Unmatched frames on two RED MX

Yaron Harel

Yaron Harel

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Hello all,
we made a test with two RED MX preparing to shoot 3D project, we use two Zeiss Ultra prime 35 mm lenses and two RED MX build 36.10 software version, when we try to match the two cameras after we adjust them on the 3D rig we notice by adjust the 3D monitor to side by side frames that the frames doesn't match it's unmatched a bit on 4K 16:9 and there a big deferment on 2K 16:9.
is anybody can help me with this?
Thaks Yaron.
 
Yaron,

3D is a simple yet extremely complicated procedure, were so many things must be taken in consideration beside simple alignment.

Did the two lenses used were Matched for 3D?

Did you calibrate the 3D rig?

It will be almost impossible to answer your a question to your problem with out knowing all the variables.
Was it a Parallalx shoot side by side, or on a beam splitter? Which 3D rig was used?

Do the images do not pair do to the convergence, or the interocular disparity is too great?

Is it the lighting difference from frame to frame on a Beam splitter rig you talking about?
Or is the image framed differently and unmatched?

What and how exactly the images do not match? Sample?
 
Hello Keith and Ketch,
I'll try to answer most of your questions, the unmatched was on the size of the frames, the lenses was two Zeiss 35mm ultra prime well calibrated lenses, we use Stereotec Live Rig as 3D rig, Ketch about your question about rig calibration I think I maybe have an idea, the cameras on the rig can move backward and forward so maybe the vertical camera (the one that reflect) was to far from the mirror and that was what cause the unmatched, the cameras was totally parallel position and no convergence was done, for monitoring we use Panasonic BT-3DL2550 monitor that can show overlay/line by line/side by side view and 3D simulation, and yes I know that 3D can be very simple and on the other hand very complicated but I'm doing 3D for couple of years and learned all the time.
thanks for your answers, Yaron.
 
any knock in the lens too, shifting elements every so slightly can attribute for the unmatching in framing. the focal length my no longer be that true focal length anymore. Even if the lenses were made together to match, somewhere down the line, something about them isn't going to match anymore. a 25 mm lens getting knocked around, won't look the same as a brand new made 25 mm. Even focus can shift depending on what elements got mis aligned.

It's integral to have a good post solution, that works in conjunction with production to compensate for all this stuff. RED allows a great deal of flexibility in the R3D to let you do all this right in RCX. so much resolution you can resize, shifts in color compensated with RCX. etc.
 
I assume that when you say your frames don't match, you mean that one camera is seeing more than the other camera. One quick way to test whether it's the beam splitter rig or the cameras (/lenses) is to simply put them side by side and see if you still have the problem.
If you do, well there's no easy way to change the zoom on primes or to change the physical position of the sensor in the camera. So if you want to move ahead with this gear, you may have to do a test in post and see if you can adequately match the geometry without too much abberation. If it's consistent, then you really only need to know the correction parameters from one set of frames and you can apply it to all your footage. A lot of extra processing, but - it "could" be that simple.
There's a script that works within After Effects - exporting a set of frames to stereo photo maker, which has automated geometric correction - then bringing it back in to apply to a full clip. Cheaper than something like Ocula or Iridas or the like.

Note - take extreme care in analyzing in terms of vertical parallax. My opinion anyway.
 
The lenses may be different unless they have the same letter on the focus scale, from memory there are 7 different focus scales for UP's, get 2 matching ones & they will match quite well.
 
Hello all those who response,
from your answers I understand what I have to check, as I said in my previous massage the frame of the left (vertical) camera was a bit little from the right (horizontal) one, the only thing I didn't check was the distance of the vertical camera from the mirror that reflect the image of this camera, at the moment I can check this issue I'll do it and post my results immediately in this forum.
Thanks to all of you, Yaron.
 
I hate to be blunt........but if your are prep'ing a 3D shoot and you can't overcome this issue then you need help.

but Ketch is right.......there is alot of variables here to go over and check.

It sounds like you have 2 different "fields of view" almost as if you had 2 different focal lengths on the camera.....I would check the epic settings.

other wise this is really something that someone needs to be there to help you troubleshoot.

Good luck....!!!!!!!!


have fun!
 
I guess I'll throw a few simple ones out there real quick.

1) MAKE SURE that the lenses are EQUAL distances from the mirror. Place a piece of bright tape on both sides of a lens, on both camera/lens sets. This makes it a bit easier to make sure your lenses are equal distances from the mirror. They should look damn close to being "one lens". Your rig should be at it's "0", no I/O, zero parallax to match the two lenses. If the two are the exact same distance to the mirror, that's one variable eliminated.

2) One thing that wouldn't really affect your problem, but MAKE SURE the cameras are both perfectly back focused. Will cause headaches after the rig is built, so do it first and do it right.


And a question, is this happening on multiple focal lengths (different lenses)? Did the rental house know this is for 3D, or should I say, have they rented them out as a set for 3D jobs before? Can you vouch that they match, or did someone (the rental house) tell you that it's a matching set of UP's?

just trying to help eliminate variables.
 
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