google these keywords and you’ll learn a heck of a lot about green-screening.
“the specialist green screen”
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“If the blur comes from a too slow shutter speed or by too narrow depth-of-field, you’ll have to tweak the keyer and possible sacrifice other parts just to manage the fuzzy edges.
A blurred edge between foreground and background means that you will have to compromise between the edge and despilling settings, and quite possibly have to keyframe these settings to compensate for different levels of blur on different parts of the clip.
Instead, add motion blur in post by using optical flow technologies such as ReelSmart Motion Blur and add depth-of-field by layering chroma clips and post-blurring them.”(the specialist)
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its impossible to answer your lighting, spill, and shadow problems precisely without seeing a high quality photo of the original shot, but I’ll tell you this, I’d rather face horrible green spill problems than slow shutters. Also, try a demo of Primatte Keyer Pro. It’s a little more intuitive with mouse clicks and transparencies.