jason_greenberg_motamedi Posted January 2, 2003 Share Posted January 2, 2003 I notice that on a number of older stutters, Compounds and Compurs, as well as on many barrel mounted lenses, the aperture has a significantly higher number of blades than on newer copal shutters, so older the aperture of older shutters approximate a circle better than newer ones. What (if anything) is the signficance of this? I know that printers use (or used) waterhouse apertures enabling them to control not only the size but also the shape. Does it matter for LF use if the aperture is pentagonal, octogonal or circular? Link to comment Share on other sites More sharing options...
ole_tjugen Posted January 3, 2003 Share Posted January 3, 2003 The number of blades will affect the shape of out-of-focus highlights. While I see no reason for having 24 blades (Compound #5), you will surely see the difference between 4, 6, 8, 12...An extreme example is 35mm mirror lenses, which have donut-shapet highlights. This can really ruin "bokeh", I guess? Link to comment Share on other sites More sharing options...
david_goldfarb Posted January 3, 2003 Share Posted January 3, 2003 Rounder is thought to be less distracting for the rendering of out-of-focus highlights, but it's not as big an issue as the design of the lens. Lenses for 35mm and medium format SLRs with auto-diaphragm lenses usually have many fewer blades to reduce shutter lag by making it possible to stop down the lens from wide open to the taking aperture more quickly. This was not an issue for older, manual diaphragm lenses. Link to comment Share on other sites More sharing options...
eric_mims Posted January 3, 2003 Share Posted January 3, 2003 Look near the bottom of this page for an example: http://www.photozone.de/3Technology/lenstec3.htm ~~Eric Link to comment Share on other sites More sharing options...
murrayatuptowngallery Posted March 14, 2006 Share Posted March 14, 2006 I was just told in a physics class that odd vs even number of blades is also a qualitative parameter in the optical transform behavior (shows up as artifacts) because different Fourier components result from odd vs even. One produces a 'star' effect. Knowing that odd and even blade lens designs exist makes me wonder if ther are any even number lenses are 'cult-classics'. That popular 'Hasselblad' (Zeiss?) lenses have odd (and only 5) may be a combination of economics and reliability (low number) and designer preference for visual artifact (odd number). Not important to many people, but I consider photography part art, part science & the geek side of me is interested in the science part. Murray Link to comment Share on other sites More sharing options...
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