The Sweet50 optic is part of Lensbaby's Optic Swap System. The system offers two different mounts that attach to the camera like a lens, and then you can choose many different optics with the effect you want to insert into the mounts. Apart from the Velvets, which are only offered as stand alone lenses, all other effects can be purchased as lenses for this very interesting system. I really appreciate being able to carry several optics with me with minimal weight and bulk.
As the name suggests, this optic creates a sharp, rounded image area surrounded by blur and soft bokeh.
It is a lens that I really appreciate for its softness and it is definitely ideal for my floral photography style. Thanks to the macro discs I can also photograph details. Trying it on both mounts, the Lensbaby Composer Pro II and the Spark 2.0, I could see the different results. The Spark can be tilted more, creating a 'pulled' effect of the blur.