The eleven things I check

A post producer asked me recently how you know when a VFX shot is finished. How do you know when it looks real.

"Real" is the wrong test. When a shot is working you don't register it as a VFX shot at all, so "does it look real" is a question you can't feel your way to. By the time you are asking it, you are already looking too hard.

What you actually do is run down a short list of tells. Every one of them is a place the eye can catch and stop believing the frame:

• Black point
• White point
• Saturation
• Contrast
• Edges
• Focus
• Volume
• Light
• Mass
• Grain
• Lens characteristics

Most come down to one question: does the element sit in the plate the way a real object would, with the same blacks, the same falloff, the same weight. The last one is the tell people forget, and it is really a whole family. A real lens leaves a fingerprint on everything it photographs: the way it renders an out-of-focus point into bokeh, the colour it smears at the edges, the distortion, the halation blooming around a highlight. Match the element and miss the lens, and a flawless composite still reads as pasted on, and nobody can quite tell you why.

None of this is making it real. It is making it unnoticed. The shots people remember as great VFX are usually the ones that failed a little, just enough to be seen. VFX are done well when nobody mentions them, because they never registered as something that wasn't just in front of the camera.