Explaining the numbers on lenses
Posted 09/09/2014 - 23:03
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Aperture is indeed a ratio, it's the ratio of the opening through which light can enter to the focal length of the lens. It's often abbreviated.
Mike
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Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
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Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
Posted 10/09/2014 - 07:59
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"Aperture Value" (AV) is the aperture value you set when in AV mode.
I'm guessing that "Aperture=" is the AV set by the camera when in other than AV mode.
I'm guessing that "Aperture=" is the AV set by the camera when in other than AV mode.
Posted 10/09/2014 - 08:16
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I've never got totally to the core of this, but I have assumed that the aperture is indeed the one you have set and the aperture value is the wide open aperture of the lens at that zoom point.
Best regards, John
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3670 posts
11 years
Slap in the middle of England
We all know that there is a lot of information engraved on lenses and there are more used to describe them. I understand the focus ring, the aperture ring and the DOF scale but I am endlessly puzzled by the basic descriptor (for example)" 1:2.8 50mm".
I know it is f2.8 wide open but I don't know the significance of the "1:" that precedes it. It looks like a ratio of some sort(?)
Similarly, in EXIF data you find "Aperture=" and below that, "Aperture value=". What is the difference?
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