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Sigma 18-200 blijkbaar toch echt 200mm en zelfs meer.
Uitleg van Sigma op de vraag of het nu wel degelijk 200 mm is of niet :
Thank you for your inquiry. Evidently, you (and others) are not familiar with how lenses are described, nor how they focus to different distances (especially inner focus lenses), and how they perform. A lens’ focal length and aperture are described when the lens is focused on infinity, because these characteristics will change as the lens is focused to different distances. By convention, most manufacturers adhere to a +/-5% tolerance for these characteristics. An ordinary lens’ focal length can become greater as the lens is focused to closer distance. It also becomes physically longer. The focal length of an inner focus type lens becomes shorter, as it focuses to closer distances. But, its physical length remains constant. The amount of change can vary depending on the type of lens, the lens’ maximum focal length (at infinity), etc. The posted comparison test images were obviously not made with the lens focused to infinity, therefore this shortening effect of inner focus is evident in the image made by Sigma 18-200mm compact zoom. When Popular Photography magazine reviewed the Sigma18-200mm DC lens (August 2005 issue), they measured the focal length (at infinity) to be 205.24mm. Popular Photography is long-established, well respected “brick and mortar” photographic publication, whose staff is accustomed to objectively and scientifically testing and evaluating photographic equipment. We do not believe this constitutes misrepresentation or false advertising, but thank you for your support. {FYI the maximum focal length of the Tamron 18-200mm XR Di II (July 2005 issue) was measured to be 196.10mm. Fancy that.} Things aren’t always as they seem are they? As Kenyada posted, ”The internet can be a rumor mill/hoax harborer.”
We hope this information is helpful to you.
Sincerely
SCA
Thank you for your inquiry. Evidently, you (and others) are not familiar with how lenses are described, nor how they focus to different distances (especially inner focus lenses), and how they perform. A lens’ focal length and aperture are described when the lens is focused on infinity, because these characteristics will change as the lens is focused to different distances. By convention, most manufacturers adhere to a +/-5% tolerance for these characteristics. An ordinary lens’ focal length can become greater as the lens is focused to closer distance. It also becomes physically longer. The focal length of an inner focus type lens becomes shorter, as it focuses to closer distances. But, its physical length remains constant. The amount of change can vary depending on the type of lens, the lens’ maximum focal length (at infinity), etc. The posted comparison test images were obviously not made with the lens focused to infinity, therefore this shortening effect of inner focus is evident in the image made by Sigma 18-200mm compact zoom. When Popular Photography magazine reviewed the Sigma18-200mm DC lens (August 2005 issue), they measured the focal length (at infinity) to be 205.24mm. Popular Photography is long-established, well respected “brick and mortar” photographic publication, whose staff is accustomed to objectively and scientifically testing and evaluating photographic equipment. We do not believe this constitutes misrepresentation or false advertising, but thank you for your support. {FYI the maximum focal length of the Tamron 18-200mm XR Di II (July 2005 issue) was measured to be 196.10mm. Fancy that.} Things aren’t always as they seem are they? As Kenyada posted, ”The internet can be a rumor mill/hoax harborer.”
We hope this information is helpful to you.
Sincerely
SCA
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