0
\$\begingroup\$

Given all details such as focal length , aperture etc , how can i find the size of a point on a paper that is at a given distance from a mobile camera ? Or vica versa , the distance required to resolve a point of a given size ?

Improve this question
\$\endgroup\$
4
  • \$\begingroup\$ I think I know what you mean, but a point by definition has no size. Can you more exactly describe what you want to know? \$\endgroup\$
    – mattdm
    Sep 8, 2019 at 23:18
  • \$\begingroup\$ @mattdm I am considering a point from a practical aspect . Take it to be a 10x10 px picture on a laptop screen \$\endgroup\$
    – Puja Dhinchak
    Sep 9, 2019 at 14:01
  • 1
    \$\begingroup\$ Possible duplicate of What is the farthest a camera can see? \$\endgroup\$
    – mattdm
    Sep 9, 2019 at 16:31
  • \$\begingroup\$ Since you note in a comment that what you want is the purely-theoretical limit, see the answer about diffraction limits in the previous question linked above. \$\endgroup\$
    – mattdm
    Sep 9, 2019 at 16:32

2 Answers 2

Reset to default
2
\$\begingroup\$

Experimentally:

  • Take a picture of a sheet of ruled/squared paper.
  • Open the photo in an image viewed/editor
  • Measure the distance in pixels between two lines
  • Divide the physical distance (in mm/inches...) between two rules by half that value. This will give you an estimate of the smallest thing you can see in a picture, if the lens is good enough for the sensor.

You can also find lens test charts on the web that may tell you a bit more about your camera.

Improve this answer
\$\endgroup\$
2
  • \$\begingroup\$ I am more concerned about the theoritical physics behind this measurement \$\endgroup\$
    – Puja Dhinchak
    Sep 9, 2019 at 14:04
  • 1
    \$\begingroup\$ @PujaDhinchak Then ask in Engineering... \$\endgroup\$
    – xenoid
    Sep 9, 2019 at 14:15
1
\$\begingroup\$

No. You can't know this from the technical specs you are thinking of. The resolving power of a camera system depends on the way the lens is built and the properties of the recording medium — and other factors such as lighting and atmosphere.

You may be able to get some details of the recording medium — the sensor — from camera specs, but not enough to be really useful in practice. And for lenses, the resolving power is characterized by testing, not calculated in theory.

Improve this answer
\$\endgroup\$
1
  • \$\begingroup\$ I want to know the physics/calculations behind . Please ignore all practical factors that can affect it . Eg ignore air refractive index , lens quality . Take everything ideal\ \$\endgroup\$
    – Puja Dhinchak
    Sep 9, 2019 at 14:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.