Working around horizontal light spill with Chromakey

<p>When using a Chromakey technique, obviating light spill from a rear vertical plane doesn't seem difficult to accomplish. Just move the subject from the vertical plane—perhaps as much as 20' in front of it. However, obviating light spill from the horizontal plane doesn't seem as straight forward as the subject can't be moved above it. Given that I meter light on both planes so that the color is as uniform as practical throughout the scene, how would any reflection from the horizontal plane be avoided? If I reduce the EV of the horizontal plane to a level that does obviate any reflection, which may require several EVs, won't pulling the key be impaired?<br>

Appreciate some input. Thanks in advance.<br />CW</p>

<p>I have the same problem and haven't found a satisfactory solution. I keep the base of subject (legs, feet, etc..) out of frame for right now.</p>

 

<p>When I have to shoot a head to toe key, I use white as the background,<em> </em> white will reflect white which is alot easier to deal with spill than green or blue.</p>

<p>@Beerbrain/Ronny Perry<br>

I do similar to you and then mask out the background and layer in something else. However, that doesn't remove a "white-cast" for anything in the subject that is say 50% opaque. See through fabric, for example, will still have "white spill." Chromakey does a great job in such cases.</p>

 

<p>I called Jim Tierney at <a href="http://www.digitalanarchy.com">www.digitalanarchy.com</a>. He readily agreed that light spill from the key color on the floor was tough to prevent. He mentioned a few ways to reduce it, such as stragically placed black matte to reduce the amount of reflection overall and floor lights. He also has a video on post work to paint out the spill—I learned something from that and perhaps it is the best solution. The video is here: <a href="http://tinyurl.com/nv84ro">http://tinyurl.com/nv84ro</a>.</p>