(Roughly) Visualizing Camera Coverage Area Using a... Ford Ranger?

Playing around with the incomparable lens calculator in Metric Mode I happened upon this equality:

When using a 1/3" sensor*, if the distance to subject (measured in meters) = focal length (measured in millimeters) then the HFOV is ~5m (4.8m to be exact). Could this simple equality be turned into a rough estimation rule of thumb?...

******** *** ****** **** **** ************ * *******. **** ****:

***** ******(******* ***),

** **** ***** ~** (*.**) ****. ********* *** ***** ***** would ** ********** ****** (******) ** *** *****'* ******* ** one **** ***** *:

  • ******** **** *** ***** *********
  • ******** **** *** ***** **25m away
  • ******** **** *** ***** *********

****** ********. **** ***********, **** ***** * */*" ******, ** thenumber ** ****** to the subject is the same as the number ** *********** in the lens length, then the HFOV at that distance is always the size of a Ranger.

**,big **** you say, what good is that when my focal length and distance to subject are ********, **** **% ** *** ****? ******* *** *** ******** * ***** **** ** *** **** ******* ** *** ****/****** **** *******, *** *** ******** **** points. **'* **** * **** ****** ***** **** *** ****'* make ** ***** ***** ***** * **********.

** ***'* *** *** **** ** ********* *** **** ******** of ********* *** **** * ******* *****, *** ***** ******* * Ranger ********** ************* *** ****. **** * ********, ******** ** *** ****, with *** ***** ********* ** **** ****** ** *** ***** and **** ********** ** *** *******. ********** ****** *** ******** would ** ******* ** *** ****/******.

*** * ****** ******, *** *** * ******? ******* * Ranger ** *** **** ********** **** ** ******, *.*, ** a */*" ****** ** ** **.

****** ******* **** ******** ********* *********. *** ******** * */*.*" sensor ***** ** *.***.

***'* **** * ***** ****** ** ******* *** ********* ******/**** coverage ***** ********* ******* *** *** ** **** *******, *'* not *** ** ****, ***.

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***** *** * *** * "*********" ******** **** ****** **** had * *** ** **** ***** ** *** ****. *** idea *** *** ***** **** ** ** **** ****** *** fit * *** ** ******* * *** ** *** *****, and ********** *** ******* * ***** ***** *****. *********** *** same **** ** **** *** ******** ****. ** ***** ** useful *** ***** ******* *******-***** ****** ****** (****** **** * was ***** ** *** ****), *** **** ** ******** **** something ***** ******* *****.

* ***** ***** ** ******* **** ******* ** * ***** quantity, *** ** ***** ** **** ** ****** **** ****.