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Old Feb 19, 2007, 6:38 PM   #11
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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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Old Feb 20, 2007, 10:18 AM   #12
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TCav wrote:
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On the other hand, some companies (Leica, for one) can work miracles with glass. After all, who else makes an f/1.0 lens?
Actually Canon made a 50mm f0.95 lens back in the 35mm film days. The had to use one aspheric plastic element as well as glass elements to get it done.
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Old Feb 20, 2007, 10:26 AM   #13
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ac.smith wrote:
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TCav wrote:
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On the other hand, some companies (Leica, for one) can work miracles with glass. After all, who else makes an f/1.0 lens?
Actually Canon made a 50mm f0.95 lens back in the 35mm film days. The had to use one aspheric plastic element as well as glass elements to get it done.
Leica also made an f/0.98 lens a while ago. I think it was a 40mm.
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Old Feb 20, 2007, 9:17 PM   #14
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TCav wrote:
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Leica also made an f/0.98 lens a while ago. I think it was a 40mm.
Did you ever see one in the wild? I sawthe Canon in the wild about '71 and had no success at all talking the owner out of it.
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Old Feb 21, 2007, 1:53 AM   #15
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robbo wrote:
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I really like superzoom cameras. I like DSLR's, too, but have a limited budget, so my love of DSLR's is not often expressed by a purchase.

The Panasonic FZ20 had a maximum aperture of 2.8 from wide angle all the way to 12X optical zoom. My Fuji S5200 has a max aperture of 3.2 at its full telephoto 10X optical zoom setting. However, most superzooms don't have such wide apertures available at full zoom. I have the Fuji S9100. I think it tops out at f4.9 or so at 10.7 optical zoom. The soon to appear Olympus SP-550 is about the same at its full 18X optical zoom.

What I would like to know are the difficulties of getting these wide apertures at full telephoto. How come Panasonic could do it with the FZ20 but hasn't done it with newer cameras. How come the other camera makers haven't done it either?
Our FZ20s have a larger lens in relation to the size of the sensor.Cannot find the page of specs right now but that is the short answer.

Fact of the matter, no other "superzoom" has a constant apeture (not to my immediate knowledge).
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