*********** *** ********* ****** ** * 2:1 ****** **** ***** ***** ******:

******, *** ******** ** *********** ****** always *** ********* ****** ** **** chart ************:

*******, * ******* ** *********** ****** use ********* ****** ** ***** ***** in *** ***** **** ** *** 10 ** **% *****.
******, *** ***-***********, **** ** *** home *** *** ******, ***** ***** lenses *** ********* *** **** **** type *******. ** ****, ********* ***** segments (**** / ***), *** ********** of *** ******* ***** ***** ***** lenses ** ****** ~**%.
Why ********* ** ***** *****
***********
*** **** ****** ****** ** *** varifocal ******, ***** ** ***********, *** to ******** *** *** *** *** end ****'* **********:
- "********* ** **+% ** *** *********** due ** *** **** ******** *** camera ** **** *** **** *** client *****"
- "** **** ***** **** ********* **** often **** ********* ** *** ********* to ************** ******* ********** ***/** ******** **** of **** *** ********************* ** ***** ********* ****."
- "**** **** *********** ** *** *** user *** ***** ***** **** **** to *** * ********** ***** ** view, *** **** ***** ****** *** live ***** ***** **** ** ****** widen ** ******* *** ***** ** view."
- "** *** ********* ********* ** ***** our ********** **** ******* ** ****** the***/***** ****** ** **** *** ******** preference"
- "** *********** *** ***** ************ ** support ** ************ ******* **** *** to ******* *******, ***** **********, ***/** customer."
- "** **** *** *********** *** *** technicians ****** ** ** **** ** change *** ********** ** *** **** if *** ******** ******* ***** **** about **** **** **** ** ** important ** ****."
***** **** *** ***** ****** ***** mind ***** ***** *** **** * FoV **** ****, ***** *** ****** is *********, ********* ******* *********** ** quickly **** ****.
*******, *** ********** ******* * ********* approach ** **** ****, ******* ***** varifocal ******, ********** ****, "** ***** ********* focal ****** ******* *** **** *** whichever *** ** ********." ** *** contrary, ** ******* ********** *****, ********* "****** ** ******* *** ************ **** we******** ** ***** * ****** ** lenses."
****
*** ***** ***** ******, *** ***** number #* ****** *** ***** ****, not ****** *** *** **** ******, but ******* ***** ***** **** ******* are ********* **** *********, **** ******** cameras *******. ********** *****:
- "*** **** ****** ** ** ***** is ******* ** ****."
- "** *** ***** ***** ****** **** we **** **** **** ********* ********."
- "********* **** ***********. ***** **** **** is ********."
- "** **** ** * ****** *** you **** ** **** * ********** wide ****, **** ** *** **** likely ** ****** *****."
*******, **** ** **** **** ***********, as *** ********** *********, "* ***** ********* ********** ** ***** *** **** typically **** ***** ******* *****, *** example ** **** ** ******* *** & *** ***** ****'* ****** *** you **** ** ** ** ****** end ***** (*********) ** **** *** WDR." ****, **** ** *** ******* fixed ******* ****** *********** ******* *** (indeed *** ** * ****** / encoder *************, *** ****) *** ********* fixed ******* *** ********* *** ****** cost, ********* ******** **** **** ***.
***** ***** ****** *** ******** ******* **** ********* ******. ******, fixed ***** ****** ****** *** **** of ******* ***** *** ** ***** (but ********* ** *** ********* ** as ***** ***** ****** ********* **** with * **** ***** **** *** be *** ** *****). *******, ************* typically ******* ***** ***** ****** **** simple *******, ***** **** ******* ******* and************.
*********** ************
*********** ***** * ****** ** *********** applications ***** ***** ****** *** *** norm - **** ** ******* /**********, ******* *** ***** **** ********** cameras.
Comments (13)
Rukmini Wilson
Is it a myth that varifocal lenses have higher f-stops 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?
Create New Topic
Paul Galburt
In the world of photography, fixed focal length lenses (often called prime lenses) enjoy a significant quality margin over vari-focal (zoom) lenses, and generally have a smaller numerical "F" number meaning more light gathering.
Because the sensors in security cameras are so small, lower F number are relatively easier to acheive than with photographic camera lenses. Also, lower F numbers mean shallower depth of field (DOF). Shallow DOF is often prized in photography as it isolates the main subject from the background. This is almost always a real negative in security.
Also, while low F numbers are good for low-light performance, most security cameras use other means to improve low-light performance.
So, interestingly, the ideal security lens in any given situration is almost the reverse of the design of a photographic lens.
Create New Topic
Ng Choy Mei
Seems that varifocal lens is more popular and flexible.
Create New Topic
David Johnson
Good points all. I've often found that Optics knowledge is missing or downplayed amongst IT professionals moving into the surveillance realm. Had one instructor claim that any adjustment necessary could be made with the cameras setup software. As Charlie Pierce used to say 'We're gathering light first and foremost'.
Create New Topic
Chin Liang Benjamin Lee
During previous installation, indeed many customers prefers to use vari-focal lenses due to the reasons mentioned above...nice sharing.
Create New Topic
Charng Haw Guo
Simple yet easy to missed.
Create New Topic