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#1 Jase Ryan

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Posted 12 June 2007 - 03:21 AM

Sorry for this novice question, but can someone explain to me what the 11:1 describes when talking about a zoom lens? I know it's telling the focal length in some way, But how do I know how many mm's a lens is based on this ratio?

Thanks
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#2 David Mullen ASC

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Posted 12 June 2007 - 08:38 AM

Sorry for this novice question, but can someone explain to me what the 11:1 describes when talking about a zoom lens? I know it's telling the focal length in some way, But how do I know how many mm's a lens is based on this ratio?

Thanks


You don't know the specific focal lengths, just the range. So if a lens starts at 5mm and has an 11:1 ratio, then it ends at 55mm (5x11=55).
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#3 Laurent Andrieux

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Posted 25 June 2007 - 07:16 PM

Sometimes, and more commonly, I think, they are given at 14:9 for instance, meaning it's a 14mm to 126 mm (14X9=126). But this ratio is very informative on the lens ability, regardless to its minimal focal length, since this minimal focal length is usually limited by the format. A 30:1 or a 40:1 lens is very "strong" zoom for instance.
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#4 chuck colburn

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Posted 25 June 2007 - 07:22 PM

Hmmm....

Sure were a lot of those Angenieuxs marked 10x12 and 10x25 etc. Mayby the French versions were marked the other way around. Don't know.
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#5 Laurent Andrieux

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Posted 25 June 2007 - 07:36 PM

I actually was thinking of an Angenieux zoom when mentionning 14:9, as an example... (An old SD TV one, actually). And I realize you're right, it's a 9mm to 126, sorry so. And the 10X12 you're refering to was the 12mm to 120 mm (16 mm), the 10X25 a 25 mm to 250mm (35 mm)...
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