I know from selling on the auction site that lenses with multiple blade "near circular" apertures are in some demand due to their perceived effect on the out of focus areas - the so called "Creamy Bokeh". The Pentacon 135 and 200mm Meyer Optic designed telephotos having 15 blade preset apertures are a good example. Pretty much all lenses with more than 9 blades were plain manual or preset, and non-automatic, although some semi-automatic lenses had more. For example the 300mm Tair, which came with the Photosniper set, had 16 blades which closed down automatically, but needed to be opened back up again manually It occurred to me to wonder why they were made with so many blades, at a time when (as far as I remember) no-one cared a toss about Bokeh. They must have been very expensive and labour intensive to make. What was so special about a near circular aperture? And what about enlarging lenses, where out of focus rendering seems totally irrelevant? Some of those had multiple blades too. Any thoughts?.