Controlling the Blur in Homemade Lenses
Getting SA under control does not necessarily mean eliminating it altogether. SA is the primary ingredient for producing beautiful soft focus effects. The trick is getting SA to produce images that are generally sharp, and in which the bright highlights are surrounded by a subtle glow.
Let's take a careful look at what happens as we stop our homemade lens down.
Starting wide open (in this case f/ 1.5), the photo on the right shows the expected soft image with a wide, dense glow surrounding our bright subject.