Chroma Key

Discussion in 'The Professional Gallery' started by ort, Dec 26, 2005.

  1. ort

    ort TPF Noob!

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    Here's the problem:

    The background must se evenly lit. The model on a 1 to 1 with the back ground. The key carries the load. The fill bouncd off the wall. Hair/model-backlight at no more than 15% of the total light on the model. I'm losing the shadow details. If I increase the lights I have to increase the backdrops lights. The bright background spills on the model. If I move the lights I get a shadow on the backdrop which forces me to jack up the backdrop lights???

    This is an endless circle.

    Is the background floressant (sorry, no spell check). This would solve the problem but the spill will increase and be in the UV range. Filter?

    Spot metering helped but I wont have the freedom if I use this.

    I want to pick the brain of someone who works or has a CK studio. I have a few talents. I'm sure we can help each other.

    Ort
    www.artbyort.com
     
  2. Unimaxium

    Unimaxium TPF Noob!

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    I'm no studio photographer, but if you're having problems with the colored backdrop spilling onto the model, then why not just increase the distance between the two? If there's a greater distance, then the light reflecting off the backdrop onto the model should be less intense. The backdrop itself will stay evenly lit, and you will be able to increase the lights on the subject more without it brightening the backdrop as much. I bet this suggestion is ignorant somehow (I have zero experience in a studio), but thought I'd post my thought anyway. Someone else who knows what they're talking about will hopefully come along and help better than I can. Good luck.
     
  3. df3photo

    df3photo TPF Noob!

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    I agree with Unimaxium on increasing the distance.
    By chroma key, do you mean that the background is chroma key green or blue? like what they do on the news durring the weather? if so, get a light and toss a colored gel over it of the oposing color of the back ground... Its been awhile but I think at the school I worked at in the TV studio it was painted chromakey green and they used a magenta gel over the lights and pointed them at the back of the subject (you model or tallent) to cancel out the green reflections... give er a try...

    did that make sence? (sorry im a few beers into the night...)
     
  4. terri

    terri Administrator Staff Member Supporting Member

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    Hi Ort - I'm moving your thread over to the Portrait forum, where it will get some more views and, hopefully, you'll get some more input on your lighting situation. :D

    Welcome to TPF!
     
  5. ort

    ort TPF Noob!

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    Similar to weather studios but they avoid my problem by not shooting full length. The backdrop is 12 feet behind the model, however, their feet are standing on it. I asked a local director who has a chroma key studio in town and he's allowing me to visit a filming today. I like the gel idea and will try it tonite.
     
  6. ort

    ort TPF Noob!

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    [​IMG]
     
  7. Unimaxium

    Unimaxium TPF Noob!

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    Awesome! So what exactly was it that got you the final result you wanted? Did you do the gel thing? Did you learn any good tips from the director at the filming? That's a pretty nice final result. What was the final setup?
     
  8. ort

    ort TPF Noob!

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    I signed a non-disclosure at the studio so I can't go into their set up but what I was doing wrong was following out dated information. You don't need gel filters, backlighting or anything else as these things are required for the softwares inability to extract chroma key screens. PS requires even lighting. Ultimatte advantedge doesn't! Ultimatte even retains the shadows if you want. The model in the shot was poorly lit as this was shot prior to learning the secrets. An even light on the backdrop helps but a clean plate of the screen, the background and the original is supplied to ultimatte. The SW takes a long time but it even lets you match the white bakance of the forground with the background and the spill is cleaned up for you. It even feathers the edges based on the resolution of the image.

    There are a few little things that I had to come up with and a few little bugs but I've a shoot today and I'll be putting the studio to the ultimatte test (sorry ;)).

    The background in this pic is just a SB-600 laying on a black card. The shadow in the center is from a reflector behind the model. I think the image would have been more dramatic if she were shirtless so I'll work on that.

    The model was shot with a modified rembrant, Key, fill and one reflector.
     

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