I sometimes enjoy pictures with distinctive 'swirly bokeh', like the kind produced by my beloved Hobson Cooke Kinic 25mm f/1.4: Subscribe to see EXIF info for this image (if available) Subscribe to see EXIF info for this image (if available) Seeking this look I recently purchased a Helios 44-3, which is supposed to have the same qualities. For example, see this: Swirly Japanese maple | Flickr - Photo Sharing!. The Helios is based on an old Zeiss biotar design, and from my understanding the only differences among the different versions are the coatings and number of aperture blades. The optical design is identical. However the copy I received was completely unable to produce any kinds of swirls, no matter how I tried. None! So that got me thinking (always a dangerous thing) . . . What lens characteristic causes swirly bokeh? I thought I'd read that it is a result of astigmatism, but if this is true then shouldn't all copies of the same lens, with the same design, produce the same result? Or is it something else--a result of misalignment, so that a lens that's been knocked around might produce swirls (or not) compared to one that's in better condition? I truly don't know and am appealing to the lens experts in here (you know who you are!) for an answer.