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Old May 24, 2007, 5:32 PM   #11
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NHL wrote:
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Oh come on!! you mean you don't know your own lenses better than that? To start with their is usualy ony a one stop veriance from one end to the other
As you already know from your explanation the f-stop is a ratio so the larger the focal lenght span the larger this aperture variance will be - A Sigma 18-200 for example has more than a 1-stop variance
-> f/3.5 to f/6.3
True, but again if you know your lens this shouldn't be a problem.
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Old May 24, 2007, 5:37 PM   #12
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JohnG wrote:
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NHL wrote:
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As you already know from your explanation the f-stop is a ratio so the larger the focal lenght span the larger this aperture variance will be - A Sigma 18-200 for example has more than a 1-stop variance
-> f/3.5 to f/6.3
And to Squirrel's point. If you're using manual and set aperture value to 6.3 you can zoom in/out and exposure will remain unchanged.
If you change you aperture via a comand dial on the camera this is true becuase the camera is makeing the adjustments for you. Even in manual. But if you have to change aperture via a ring on the lens then the exposure will change.
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Old May 24, 2007, 7:39 PM   #13
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tjsnaps wrote:
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If you change you aperture via a comand dial on the camera this is true becuase the camera is makeing the adjustments for you. Even in manual. But if you have to change aperture via a ring on the lens then the exposure will change.
I didn't know Canon had any lenses that still worked on current DSLRs that had manual aperture rings - this being a Canon lens forum I figured our scope was limited to Canon lenses for DSLR cameras.
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Old May 24, 2007, 7:56 PM   #14
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JohnG wrote:
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tjsnaps wrote:
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If you change you aperture via a comand dial on the camera this is true becuase the camera is makeing the adjustments for you. Even in manual. But if you have to change aperture via a ring on the lens then the exposure will change.
I didn't know Canon had any lenses that still worked on current DSLRs that had manual aperture rings - this being a Canon lens forum I figured our scope was limited to Canon lenses for DSLR cameras.
To tell you the truth I hadn't even noticed the thread was under "canon lenses". I was just responding to the general question wich showed up under "recent" I'm still getting used to this site. I shal try to pay more attention. Hope I didn't confuse anyone.
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Old May 25, 2007, 10:53 PM   #15
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Thanks everybody for the tips.
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