Varifocal vs Fixed Focal Lens

Author: John Honovich, Published on May 29, 2014

Choosing between varifocal and fixed focal lens is one of the most fundamental decisions in video surveillance.

With a fixed focal lens, the Field of View (FoV) of the camera can not be changed unless the lens is changed. By contrast, varifocal lenses allow for immediate adjustment of the FoV simply by adjusting a control of the lens / camera.

But which one is used more and why?

Inside, our exclusive integrator survey results answer these questions.

******** ******* ********* *** ***** ***** **** ** *** ** the **** *********** ********* ** ***** ************.

**** * ***** ***** ****, *** ***** ** **** (***) of *** ****** *** *** ** ******* ****** *** **** is *******. ** ********, ********* ****** ***** *** ********* ********** of *** *** ****** ** ********* * ******* ** *** lens / ******.

*** ***** *** ** **** **** *** ***?

******, *** ********* ********** ****** ******* ****** ***** *********.

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

*********** *** ********* ****** ** * *:* ****** **** ***** focal ******:

******, *** ******** ** *********** ****** ****** *** ********* ****** as **** ***** ************:

*******, * ******* ** *********** ****** *** ********* ****** ** shown ***** ** *** ***** **** ** *** ** ** 30% *****.

******, *** ***-***********, **** ** *** **** *** *** ******, fixed ***** ****** *** ********* *** **** **** **** *******. As ****, ********* ***** ******** (**** / ***), *** ********** of *** ******* ***** ***** ***** ****** ** ****** ~**%.

Why ********* ** ***** *****

***********

*** **** ****** ****** ** *** ********* ******, ***** ** integrators, *** ** ******** *** *** *** *** *** ****'* preference:

  • "********* ** **+% ** *** *********** *** ** *** **** allowing *** ****** ** **** *** **** *** ****** *****"
  • "** **** ***** **** ********* **** ***** **** ********* ** the ********* ** ************** ******* ********** ***/** ******** **** ** **** *** ********************* ** ***** ********* ****."
  • "**** **** *********** ** *** *** **** *** ***** ***** they **** ** *** * ********** ***** ** ****, *** then ***** ****** *** **** ***** ***** **** ** ****** widen ** ******* *** ***** ** ****."
  • "** *** ********* ********* ** ***** *** ********** **** ******* to ****** ******/***** ****** ** **** *** ******** **********"
  • "** *********** *** ***** ************ ** ******* ** ************ ******* made *** ** ******* *******, ***** **********, ***/** ********."
  • "** **** *** *********** *** *** *********** ****** ** ** able ** ****** *** ********** ** *** **** ** *** customer ******* ***** **** ***** **** **** **** ** ** important ** ****."

***** **** *** ***** ****** ***** **** ***** ***** *** wide * *** **** ****, ***** *** ****** ** *********, varifocal ******* *********** ** ******* **** ****.

*******, *** ********** ******* * ********* ******** ** **** ****, without ***** ********* ******, ********** ****, "** ***** ********* ***** length ******* *** **** *** ********* *** ** ********." ** the ********, ** ******* ********** *****, ********* "****** ** ******* *** ************ **** ********** ** ***** * ****** ** ******."

****

*** ***** ***** ******, *** ***** ****** #* ****** *** lower ****, *** ****** *** *** **** ******, *** ******* fixed ***** **** ******* *** ********* **** *********, **** ******** cameras *******. ********** *****:

  • "*** **** ****** ** ** ***** ** ******* ** ****."
  • "** *** ***** ***** ****** **** ** **** **** **** effective ********."
  • "********* **** ***********. ***** **** **** ** ********."
  • "** **** ** * ****** *** *** **** ** **** a ********** **** ****, **** ** *** **** ****** ** select *****."

*******, **** ** **** **** ***********, ** *** ********** *********, "* ***** ********* ********** ** ***** *** **** ********* **** ***** ******* video, *** ******* ** **** ** ******* *** & *** fixed ****'* ****** *** *** **** ** ** ** ****** end ***** (*********) ** **** *** ***." ****, **** ** not ******* ***** ******* ****** *********** ******* *** (****** *** is * ****** / ******* *************, *** ****) *** ********* fixed ******* *** ********* *** ****** ****, ********* ******** **** true ***.

***** ***** ****** *********** ******* **** ********* ******. ******, ***** ***** ****** ****** the **** ** ******* ***** *** ** ***** (*** ********* do *** ********* ** ** ***** ***** ****** ********* **** with * **** ***** **** *** ** *** ** *****). However, ************* ********* ******* ***** ***** ****** **** ****** *******, often **** ******* ******* ***************.

*********** ************

*********** ***** * ****** ** *********** ************ ***** ***** ****** are *** **** - **** ** ******* /**********, ******* *** ***** **** ********** *******.

Comments (7)

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

** ** * **** ****varifocal ****** have ****** *-***** generally than their fixed lens counterparts, and that the difference is exacerbated as you move the varifocal towards the high range of its the focal length?

** **********, *** **** *** ***** ***** ******* ******** *** the ****** *********, * **** **** ********. **** ** ********* the **** **** ********* ****, *.*., ****** ** * ****** focal ****** ***** ***** ******* ********.

******* *** ***** **** * ***** ***** ****** **** *** a ****** ***** (*.*., ***) **** * ****** ********, *.*., * *-***. *'** ***** *****, ******, ** ******* pursuing ****. ***** ******...

** ** ***** **** ** ***** ************ *****, **** ***** focal ****** ****** **** **** **** *** **** *** ******** installers ******* **** * **** ********* ** ****** **** ****, I ****** ****** ** *** **** **** **** *** ** with ****-***** ** ***** ** ********. * ********** ******, ***** at *** **** *** ********* ** ****** *** **** ********* lenses ** *** ****** **** ********** * ******** *-**** ********** the **** ***** ** *** **********. * *** **** ******* with *** ****** *** ********* ** ***** ******, *** * did **** ** *** **** ********** ***** ******** ********** *** FOV ***** **** **** **** ***** ******, ** **** ****** my **-** ****** *** * **** ****. * **** *******, though, * ***** *** ** *********** ** *** **** ***** have ******** ****... * ******** ******** ** *** ***** ****** increases? *** ** ********* *****-***** *** *** **** ********** ***** gathering *** ****** ******* ** *** ******* *****? ** ** was ***** ** ******** *****, **** ***** ************* *** ***** it ***, ***?

...********* ****** ** *** ****** **** ********** * ******** *-**** throughout *** **** ***** ** *** **********.

****'* *** *****, ** **** ***** **** **? **'* **** to ******* **** ** ***** ** ****** ** *******. **** thru * ***** ***** **** **. * ****** ***** ****, Charmin ** *** *** ****** ***** **** ***** ***, **?

** **** **** ******** *** ********* *** ********, *** ********* restricting *** **** ******** *********** ** *** ****, ** ******** the *****, **** ** **** ***** ********* ****** ****, **** would *****************.

** *** ***** ** ***********, ***** ***** ****** ****** (***** called ***** ******) ***** * *********** ******* ****** **** ****-***** (zoom) ******, *** ********* **** * ******* ********* "*" ****** meaning **** ***** *********.

******* *** ******* ** ******** ******* *** ** *****, ***** F ****** *** ********** ****** ** ******* **** **** ************ camera ******. ****, ***** * ******* **** ********* ***** ** field (***). ******* *** ** ***** ****** ** *********** ** it ******** *** **** ******* **** *** **********. **** ** almost ****** * **** ******** ** ********.

****, ***** *** * ******* *** **** *** ***-***** ***********, most ******** ******* *** ***** ***** ** ******* ***-***** ***********.

**, *************, *** ***** ******** **** ** *** ***** ********** is ****** *** ******* ** *** ****** ** * ************ lens.

****, ****** *** *** ********. * **** ** ****** ** one ***** *** ****:

"****, ***** *** * ******* *** **** *** ***-***** ***********, most ******** ******* *** ***** ***** ** ******* ***-***** ***********."

* ***** **** ****. *******, ** * ********* ****** * have ***** **** * ************ ******, *** *******, *******/*.* ********** ** *** *****. *********, ** * ************ ***** * camera ** ** **** ** *** *****, **** **** ****** spend *** ***** ***** ** ******/*.*, */*.*, ** */*.* ****, ***** **** **** **** *** spending ** ***** **********, ***.

*** *** ********* ** ********** ** ****** *******, ***** ********* have ***** ******** ******* ***** *** ***** ******.

**, *************, *** ***** ******** **** ** *** ***** ********** is ****** ***reverse ** *** ****** of a photographic lens. (EA)

***********, ***, ***********, **.

...**** ******** ******* *** ***** ***** ** ******* ***-***** ***********.

*****, ******** ***** *** ** '***** *****' ********* ** ************ cameras, ****'* *******low-light *********** ** ** *** ** ************ that other more artistic concerns, e.g. ***** *****, *** *****/**********, *************** **** ** ** **** ***. ***** *** ****** ****no ************ ****** ***** **** **. But that, as John counters, doesn't mean lower F numbers are worse or even immaterial, they still comprise the front line assault against the forces of darkness, and all other things being equal, lower is better, *** * *** ***** ** * *** ******.

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

**** ** ****. ******* ****DOF ****** *** ****** **** ** ******** *******. Why? Two technical reasons:

*) ****** ****smaller ****** = ****** ***. Witness the now ubiquitous availability of full-frame 35mm sensors in Pro DSLRs after old school photographers had enough of the 4/3 system with its ******** ****** ** *. **** ****** ********* *** ******** ** larger *******.

*) *** *******distance ** ******* ** ******* ***** enough to render it imperceptible. We're not talking close-up portrait with blurry daisies in the background. Also, if the distance ******* ****** ** **** *** ******, ***** ** *****'* ****** if *** ********** ** ***. **** ** ** *** ******.

*** **********, ** *****unlikely that the industry is ******** ****** *-***** ****** ******* **** **** ********* ***'*.

** * ***** *** ******** ***** *** ********** ********** *** constraints ** **** **********, *** **** ****** ******** ********* ****** the **** ******.

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