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#11 |
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Join Date: Dec 2006
Location: Davenport, IA
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Virtually all the 12x zooms are 6mm - 72mm focal lengths actual. The 35mm equivalencies vary a bit due to variations in the diagonal of the sensor. The diameter of the objective lens must be 25.7mm to achieve f2.8 at 72mm. If we loosen the wide open aperture requirements at max telephoto to f3.7 the diameter of the objective become 19.5mm. Further loosening the telephoto speed requirement to f4.8 the reduces the diameter of the objective lens to 15mm. Each of these reductions in the maximum aperture at maximum telephoto allow the designer to create a smaller, less expensive camera and the buyers can choose the features they need.
In the days of film many of us used 400mm f6.3 and 500mm f8 lenses routinely and they were BIG. I also had a 180mm f2.8 and it was big and HEAVY. With that frame of reference a 430mm (equivalent) f3.5 is an amazing speed demon and I don't even need a wheelbarrow. |
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#12 | |
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TCav wrote:
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#13 | ||
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Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
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ac.smith wrote:
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#14 | |
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TCav wrote:
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#15 | |
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Join Date: Aug 2006
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robbo wrote:
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Fact of the matter, no other "superzoom" has a constant apeture (not to my immediate knowledge). |
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