Canon PowerShot SX400 IS Black Manual (en)

Shooting Movies with Subjects at the Same 
Size Shown before Shooting
Still Images
Normally, once movie recording begins, the image display area 
changes and subjects are enlarged to allow for correction of 
significant camera shake. To shoot subjects at the same size 
shown before shooting, you can choose not to reduce significant 
camera shake.
to access the [IS Settings] screen.
Choose [Dynamic IS], and then 
choose [2] (
You can also set [IS Mode] to [Off], so that subjects are recorded 
at the same size shown before shooting.