The science

https://en.wikipedia.org/wiki/Scheimpflug_principle#/
media/File:Scheimpflug.gif

The science behind this effect comes down to the depth of focus and how it is faked to change perspective. The technique creates a false depth of field around the subject with blur added in during post to create the illusion that the part in focus is tiny.
It uses the Scheimpflug Principle seen in the image, named after an Austrian army Captain 'Theodor Scheimpflug', which looks at the idea that if the subject plane is not parallel to the image plane, aka the camera is at a higher, then the image will only be in focus along a certain line.

https://upload.wikimedia.org/wikipedia/commons/thumb/
d/dd/Z-buffer.jpg/220px-Z-buffer.jpg

The other science behind the technique of smallgantics is z-buffering or depth buffering that is applied through the blur effect. Z-buffering uses black and white matte areas to add or show depth of subjects inside 3D graphic rendering software. In the case of smallgantics editing you draw a black and white matte sequence around the object in the scene then assign the focus parameters.