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Well, I did my big show and...

Discussion in 'Multimedia, Projection, and Show Control' started by SjonRokz4u, May 25, 2009.

  1. SjonRokz4u

    SjonRokz4u Member

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    I took your advice and went with the monoprice RG. Power point and DVD were great, but the cam was a little different. I noticed behind the image I was showing, there was a larger duplicate image in the background. I was using a cam to a switcher to 300' of rg to the projector. Rear projection. Any advice.....Thanks, Shaun
     
  2. ruinexplorer

    ruinexplorer Minion CB Mods Premium Member Fight Leukemia

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    Just to be clear, are you talking about "ghosting"? This would be when there is signal degredation and you will get a duplicate of your image slightly offset from your main image. This is something that we have discussed that happens when the impedance differs down the signal path. It also can occur due to poor sheilding.

    If you can expand on how your gear was set up (as specific as possible with gear and cables) and a more concise definition of the image that you saw, we might be able to help you find the cause to this issue.
     
  3. SjonRokz4u

    SjonRokz4u Member

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    Thanks for helping out. I dont think it was ghosting, but i have never expirienced ghosting before. Im getting that ghosting would be an image about the same size slightly offset from your image, faint but obvious maybe like an old tv set would get (not sure if your old enough to remember, Im 45). Thats not so much the case, Ill get back to the image, 1st let me give you the set up. video was set up at front of house with the PA maybe 80' from stage. The 9x12 was center stage to ceiling height 15' rear projection screen Dalite fastfold, Hitachi projector about 6' high and far enough back to fill screen, set to mirror, then something I never saw at home in the settings, but after I mirrored it wanted a mirror h or mirror v (horizontal and vertical I assume). Now back to FoH there was a laptop for powerpoint inbetween sets, a DvD player for quick intro movie and two motion backgrounds, and a JVC GYDV500 tripoded cam shooting straight ahead to the stage and screen, all 3 items were plugged into a $50 switcher. The powerpoint and dvd looked great and were issue free so Ill leave them at this point. The cam was wired from the bnc out through a 10' or so bnc cable probably rg to the switcher and adapted at the switcher end with a bnc to rca adaptor then plugged into the switcher. Out of the switch was 3 100' lines of the RG suggested to me in my 1st post a month ago, and all 3 were coupled by bnc to bnc couplers, at the projector end there was a bnc to rca coupler then plugged into the rca in on the projector.
    As for the image, imagine the cam pulled in tight enough to get a shot of the performer from roughly the waist up. That pretty much filled the screen from top to bottom with a little frame space over his head, and a pretty good amount of frame to the left and right. i didnt notice anything until he pulled the lens back for a wider shot. So imagine the image Im shooting is now from the ankles up, behind that, very clearly defined is another image of the same thing only its considerably larger. So large in fact that my image was showing from the feet up and the other image was filling the screen and only showing about from the knees to mid torso. I immediatley made him pull the cam tighter, the secondary image pulled tighter as did my image. Once we were back to the tighter shot, the secondary image was from maybe upper thighs to mid chest and stayed there th entire night. It was definatley a live shot in the fact that it was in time with the performers movment. The cam was about 8' high, and I dont know if it matters but there was a follow spot over our right shoulder about 12' high. I hope this is everything you need to know, sorry so long winded but I wanted to try and cover everything.......................Thanks!!!!!!!
     
  4. SjonRokz4u

    SjonRokz4u Member

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    Re:A quick addition to the post

    To put it into perspective, my image filled the screen basically at 12', it would have taken about a 25' or 30' screen to frame the 2nd image the same as the 1st image
     
  5. lighthouse

    lighthouse Member

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    Was the performer standing in front of the screen? It sounds like a classic case of pointing the camera at it's own output, except in this case the output is huge in the frame.
     
  6. waynehoskins

    waynehoskins Active Member

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    Yeah, that's definitely the camera looking at itself on the screen.

    Also, just a clarification, "RG" doesn't specify any particular cable; it stands for "Radio Guide" (or possibly "Radio Grade"), an old obsolete military descriptor for coaxial cables. All old-design coaxial cables had an RG designator.
     
  7. SjonRokz4u

    SjonRokz4u Member

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    So its sort of like feedback on a monitor in a PA system. I was thinking that but didnt know if that was possible. Any suggestions on how I handle this situation when it comes up again. A center screen with the performer infront of it. These guys are wanting to do the same thing at the end of July
     
  8. SjonRokz4u

    SjonRokz4u Member

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    Just a note. The Decking of the stage is 13' below the ceiling so the screen is set up behind but up aginst the center stage decking and the bottom of the screen is about a foot above the decking
     
  9. ruinexplorer

    ruinexplorer Minion CB Mods Premium Member Fight Leukemia

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    Well, the only way to avoid this is to not allow the camera to see the projected image. I suggest having your speaker be slightly offstage one direction and the screen offstage the other direction. I would then try to have my camera set slightly off center the same direction as the screen. This will give you more options for how tight of a shot you want.

    As for your previous question, ghosting is similar to what you saw on your older TV sets. While there are more ways that you can get ghosting than what I previously mentioned, those were some of the ways that you could have encountered it with this type of set-up.
     
  10. SjonRokz4u

    SjonRokz4u Member

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    Thanks guys!!! it sounds like everyone agrees. So in July I guess Ill try to get him more off axis from the screen,or theyre talking about using 2 projectors and 2 9x12s. If thats the case, I guess its problem eliminated. Alao, in the future when having a center screen, it must be high enough that the cam doesntr pick it up. Correct and Thanks again.................Shaun
     

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