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If the camera format is 35mm, the focal length of the lens is 35mm, the aperture is f/4, the subject distance is 25ft, and the hyperfocal distance is 39'7", then what would be the range of focus when we set the focus to infinity?

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  • \$\begingroup\$ If you focus on infinity, then all objects at or farther away than the hyperfocal distance will be in focus. \$\endgroup\$
    – Count Iblis
    Sep 6, 2017 at 23:11
  • \$\begingroup\$ But if you instead focus on an object that is at the hyperfocal distance then all objects from half the hyperfocal distance away till infinity will be in focus, and that's good enough for this case to get the object in focus as well as everything else that's farther away. \$\endgroup\$
    – Count Iblis
    Sep 6, 2017 at 23:20
  • \$\begingroup\$ There's a difference between being 'in focus' (only a single distance is truly 'in focus') and being 'acceptably in focus.' \$\endgroup\$
    – Michael C
    Sep 7, 2017 at 2:46
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    \$\begingroup\$ Related: Why I am getting different values for depth of field from calculators vs in-camera DoF preview? \$\endgroup\$
    – Michael C
    Sep 7, 2017 at 2:57
  • \$\begingroup\$ Related: Why did manufacturers stop including DOF scales on lenses? \$\endgroup\$
    – Michael C
    Sep 7, 2017 at 2:58

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With the camera focus set to infinity (as far as the eye can see) the hyperlocal distance is the near subject distance that will render an object with acceptable focus. The far distance is infinity.

With the camera set to f/4 focused at infinity with a 35mm lens mounted -- the span of acceptable focus is 39 feet 7 inches thru to infinity.

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  • \$\begingroup\$ ... assuming a display size of 8x10" viewed at a distance of 10" by a person with 20/20 vision. Change any of those parameters and the hyperfocal distance changes as well. \$\endgroup\$
    – Michael C
    Sep 7, 2017 at 2:48
  • \$\begingroup\$ @ Michael Clark -- Assuming the hyperfocal distance given is correct for a specific application --- then if a camera is focused on infinity, that hperfocal distance will the near point in acceptable focus for that same application. \$\endgroup\$
    – Alan Marcus
    Sep 7, 2017 at 3:38
  • \$\begingroup\$ My comment above was specifically referring to the specific distance given in the last sentence of the answer: "With the camera set to f/4 focused at infinity with a 35mm lens mounted -- the span of acceptable focus is 39 feet 7 inches thru to infinity... assuming a display size of 8x10" viewed at a distance of 10" by a person with 20/20 vision." \$\endgroup\$
    – Michael C
    Sep 7, 2017 at 4:26

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