On this video by photographer Anthony Morganti shows to better use the redial filter in Lightroom.
The redial filter has been around for some time in Lightroom and it is a great tool for selectively changing and manipulating areas within your image. The first really useful tip Morganti shares on this video is how to create a simple oval radial filter quickly – just choose the radial tool hold the ctrl/cmd (PC/MAC) and double click on the image. If you lower the exposure you will get a nice vignette.
The second quick tip in this video has to do with creating a perfect circle (using the shift key) and duplicating it (right click => duplicate) to create to exact round radial filters.