Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Which special effects filter produces circular highlights as seen in this photo by Magda Wasiczek?
I can't say which exact brand/model of filter was used but any opaque circle with a smaller circle cut into it would produce this effect when placed over the front element the lens.
How well it will work depends on the maximum aperture and construction of the lens
I believe you also get this kind of bokeh if you use a mirror lens.
(Random google results:)
Required, but never shown