7Artisans has released a new 79mm split diopter filter. As with many filters, it goes on the end of your lens between the subject and the camera. This one doesn’t screw onto the lens, though. While shooting, you hold this one in front of your lens (or try to mount it to a camera cage) for maximum positional control.
The typical application of split diopters lets you film two subjects on very different focus planes while keeping them both sharp. 7Artisans, though, says that they have another less common effect. Split diopters, in bringing the plane of focus closer in the area they cover, also blur out your actual plane of focus. This lets you selectively blur parts of your image to, as 7Artisans describes it, “enhance your visual storytelling”.