---
title: Yellow Screen and how Mary Poppins changed film making
date: 2020-08-23T12:19:00+01:00
author: John Henry Donovan
canonical_url: "https://johnhenry.ie/blog/2020/08/yellow-screen-and-how-mary-poppins-changed-film-making"
section: Blog
---
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# Yellow Screen And How Mary Poppins Changed Film Making

Posted on 23rd August, 2020

Yellow Screen or [The Sodium vapour process](https://en.wikipedia.org/wiki/Sodium_vapor_process) used by Disney and made famous by Mary Poppins (1964) used a specially coated prism in an old three-strip Technicolor camera. They were able to film [technically brilliant mattes](https://filmmakeriq.com/lessons/yellow-screen-revenge-blue-screen/) even with transparency. There was only one camera with [this unique prism](https://www.youtube.com/watch?v=26b7uqZcXAY&t=606s). Nobody was able to replicate it, and it was only ever for 35mm film. Blue Screen was developed for larger film formats at the time like 65mm, Ben Hur in particular.

![A diagram shows an apple's image split into different colors using a prism. A camera on the left captures the apple, and a prism in the middle divides the light into red, green, and blue beams to form another apple image on a yellow background on the right.](data:image/png;base64,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)

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