I have made a blur effect that you can use to mimic selective circular and/or linear focus.
It is a Title Effect (without text) so you can edit it as a connected clip on top of the video you want to apply it to and adjust the length as needed.
In the effect controls (which you will find when you click the "title" button in the inspector) there is a pop-up where you can choose between the following Blur Types:
- a circular gradient blur
- a single linear gradient blur
- a double gradient blur
- a combination of the circular gradient blur and the double linear gradient blur
There are on screen controls for the start end end points for both the linear blurs and the centre of the circular blur. These parameters can also be altered numerically in the inspector and keyframed if needed.
Unfortunately the inner and outer radius for the circular blur don't have on screen controls, only sliders in the inspector pane.
The Blur Amount for all blurs is rigged into a single slider.
To install: unzip the file and drag the Multi Gradient Blur folder to your User/Movies/Motion Templates/Titles folder.