In Photoshop, masks have a density. In this video i will show you how you can recreate this in Affinity. The opacity of a mask only affects the visible parts of the mask where as the density also changes the global opacity of mask. I will also quickly share how you can apply a feather to a mask by using the live gaussian blur filter.
PS. I am using Affinity Designer in this video, however the steps are the same for Affinity Photo, just keep in mind that Affinity Designer does not allow you to add a live mask.
Hope you found this video useful and thanks for watching