How does a change in FL relate to a scalar change in FoV?

Started Jul 28, 2013 | Questions thread
Gerry Winterbourne
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Re: How does a change in FL relate to a scalar change in FoV?
In reply to edu T, Jul 28, 2013

edu T wrote:

Suppose I'm thinking about buying a longer lens and I want to visualize the effects of its narrower field of view by cropping-and-upsizing some already taken shots . Then,

  • If I have a picture W pixels wide shot with a L-millimeter-long lens, to which W' should I crop the picture to match the FoV of an L' focal length which is n times M?

It's the direct inverse proportion.  Twice the FL is equivalent to half the pixel width, three times is equivalent to one third the pixel width. etc ...

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Gerry
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First camera 1953, first Pentax 1985, first DSLR 2006
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