Focal Lens Length Tutorial 2012

Author: John Honovich, Published on Dec 18, 2012

Camera specifications often list lens length: 3mm, 6mm, 2.8 - 9mm, etc. These metrics are important in determining the correct camera coverage and Field of View (FoV). In this tutorial, we look at:

  • What lens focal length impacts
  • The relationship of imager size
  • Common lens length ranges and their uses
  • Limitations of using focal lens length
  • Manufacturer variances between focal length and AoV
  • Picking the right lens length

****** ************** ***** **** **** ******: ***, ***, *.* - 9mm, ***. ***** ******* *** ********* ** *********** *** ******* camera ******** *** ***** ** **** (***). ** **** ********, we **** **:

  • **** **** ***** ****** *******
  • *** ************ ** ****** ****
  • ****** **** ****** ****** *** ***** ****
  • *********** ** ***** ***** **** ******
  • ************ ********* ******* ***** ****** *** ***
  • ******* *** ***** **** ******

[***************]

Focal **** ****** ** *** / ***

***** **** ****** ** *** ******** ******** ******* *** **** and *** ******. ** ** ********* ** ************ ******* ** is *** ******* ****** ** *** *** ******* / ***** of **** (***) ** * *****. ***:***** ** **** (***) ********

Lens ****** ******

*** ****** *** ****, *** ******** *** ***** ** **** / **** ********; *** ******* *** ****, *** *****. **** is * ******** ********* ******** **** *** ******** ******* *** lens *** *** ******, ** *** ***** ***** *****:

lens sensor

*** ****** *** **** **, *** ******* ** ** **** from *** ******, ********* ** * ******** ***.

********, ** *** **** ** *****, ** **** ** ***** to *** ****** *** ******** * ***** ****, **** **:

Impact ** ****** ****

****** *** ***** **** ****** ** *** ******* ****** ** FoV ** ************, *** **** ** ****** **** (*.*., ¼”,*/*”,*/*”, etc.) **** ******* ****. ********** **** *****, *** ****** *** imager, * ****** *** / **** *** ** ********. **** is *** * **** ****** ** **** ************ ************ ******* are */*” (** ***** – ** */*.*” ** */*.*”). *******, there *** ** ****** ***********, **** ** *** ***** ****** is *** ****, ** *** ****** **** ** *** ****** is *********. *** ****, ***:************ ****** ****** ********

Rule ** ***** - ***** ****** ** ***

***** *** **** ****** */*” ******, **** ** *** *** / ********** *** ** ******* *** ****** **** ******:

*** - **°

*** - **°

**** - **°

**** - **.*°

**** - *.*°

*** ***** ************ ** **** ******** *** **** **********.

Common **** ****** ******

** ********, ************ ******* ********* **** ** *** ** * lens ****** ******:

  • ******* – ***** *** ******** ***** **** ***** ***** *** comes **** **********, **** *** **** ‘*******’. ***** **** ********* require ********* ******** ** ******* * **** / ********* *****. While ** *** ******* ********* ******, ************** *********** ******. *** our***** ** ********* ********* / *** ******* *******.
  • ‘******’ – *** – ****: *** ***** ****** ** **** cameras **** ** **** ***** (******* ** ** ** ******* FoV).
  • ********* – **** – ****: ***** **** ******* ** ** come **** ****** ** **** *****, **** ** ******** */** ****** *** ** ********* *** ********* ** ******* (typically *** **** ******)
  • ***** ********* - *****+: ****** ** **** ***** *** ********** ones **** ** *** / ******* ******* **** *** **** (typically ***+ **** ***** **** ** ****)

Warning - ************ ***** ****** / *** *********

****** ************* ********* ******* *** / *** ********* ** ******* a ***** ******. *** *******, ************* *** **** *** *********** to **** **** * ****** ** **** ***** ** ********* 50mm ** **** * ****** ** *********.

*******, ****** ***********'* ***** ******* ** *** ****** *** ** to *********** / ************ *** *** , ********** **** ******* focal *******. ********* ** ** ******* ** *** **** ** the ****** ** **** ** **** ** ******* *** ************ of *** **** ****** **** *** *********** ************. ********** ** the *****, *** ******** ** ** ****** **** ******/****** ***** on ***, *** ***** ******. **** ***** **** **** ********** ********* ** ****** ******, **** ******** ****, ** *** calculator.

Lens ***********

*** ****** *** **** ******, *** **** ****** ***** *********** will *****:

  • ******** ***** *******: **** ******, ********** ********* **** ****** ** ************, ********** have ******** ***** ******* ******** ** **** ***** ******* / ppf ******* ***** ********. ** *** *** ******** / ***** **** **** ***********, *** *** **** ** ********** **** extra ***** *******. ***:* ***** **** ** **** ****** *** **** *****
  • ******** *** ***** ***********: **** **** ****** (** **** ** **** ***** ****) typically ******* ************* **** ***** **** ****** ****** ** *** 3mm ** **** *****. ************, ********** **** ***** *****, *** longer *** **** *** ****** *** * **** (****** **** **** *********** *******).
  • ***** ** ***** ******: ************ ******* **** ****** **** ***** ** ***** ****** where ******* ****** *** ** *****. **** ** ******* **** usually *** ********** ***** ****** *** **** ******** **** *** more **** * **** **** **** *** ******. *******, **** long **** **** ***** ******** **** *** ********** **** ** resolve *** ***** **** ******* ** **** ****-**** ******. ****** our***** ** ***** ********.

Picking *** ***** **** ******

*** ******* *** **** ******, *** **** *** ****** *** capture. *************, *** ***** *** ******* ****, *** **** ******** is *** ********** ****** ********. **** ** *** ****** ***** are ******* **** **** **** ** * ********* ******* ******. Since ** ** *********, *** ******* ****** ** ****** *** since *** *** ** ** ****, *** *** ******* **** 'fuzzy' **** ** **** *** ***** ** *** ******.

*** **** **** ** ***** ** ** **** *** *** no ***** **** *** **** ** ******** – *.*., **** what *** **** ** *******. *******, **** *** ** ***** as ****** **** ** ******* * *** ** ****** (*.*., I **** *** **** ** *** ******* *** **** *** license ****** ** *** **** ******** **).

** **** ***** ****, ****** *** **** (***) ** *** metric **** ** **** ********* *** **** *** *** ** without ****** *** ******* ** *** **** ******** ** ***** that **** **** ** *****. ****** **** ****** ******* ********** ****.

**** **** *********:

******** ** ******** *******!

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