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 (13)

Rukmini Wilson

05/29/14 04:41pm

Fixed focal lenses are not lower quality than varifocal lenses...

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?

John Honovich

IPVM | In reply to Rukmini Wilson | 05/29/14 04:54pm

By definition, any time the focal width remains constant but the length increases, F stop will increase. That is typically the case with varifocal lens, i.e., adjust to a longer focal length while width remains constant.

Perhaps one could find a fixed focal length lens for a higher value (e.g., 9mm) with a lower f stop than, e.g., a 3-9mm. I've never heard, though, of someone pursuing this. Maybe though...

Andrew Lund

In reply to John Honovich | 05/30/14 06:51am

In my early days of doing surveillance video, when fixed focal length lenses were much more the norm and prepared installers usually kept a wide selection of lenses with them, I really wanted to get away from that and go with vari-focal as often as possible. I discovered Tamron, which at the time was marketing as having the only varifocal lenses on the market that maintained a constant F-stop throughout the full range of FOV adjustment. I was very pleased with the optics and mechanics of their lenses, and I did seem to get more consistent light handling throughout the FOV range than with most other brands, so they became my go-to lenses for a long time. I must confess, though, I could use an explanation on how they would have achieved this... a widening aperture as the focal length increases? Was it marketing mumbo-jumbo and the more consistent light gathering was simply because of the quality build? If it was truly an accurate claim, what other manufacturers are doing it now, too?

Rukmini Wilson

In reply to Andrew Lund | 05/30/14 08:20am

...varifocal lenses on the market that maintained a constant F-stop throughout the full range of FOV adjustment.

What's the model, do they still make it? It's hard to imagine that it could be solved by quality. Look thru a paper towel roll vs. a toilet paper roll, Charmin or not the toilet paper roll gonna win, no?

If they were widening and narrowing the aperture, and purposely restricting the best possible performance of the lens, by limiting the light, just to make their marketing claims true, that would be wrong hysterical.

Paul Galburt

05/29/14 07:23pm

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.

John Honovich

IPVM | In reply to Paul Galburt | 05/29/14 08:42pm

Paul, thanks for the feedback. I want to expand on one point you made:

"Also, while low F numbers are good for low-light performance, most security cameras use other means to improve low-light performance."

I agree with this. However, as a practical matter I have never seen a surveillance camera, for example, with an f/2.0 lens be good at low light. Generally, if a manufacturer wants a camera to be good at low light, they will easily spend the small delta to get an f/1.0, f/1.2, or f/1.4 lens, along with what they are spending on image processing, etc.

The one exception is integrated IR budget cameras, which generally have high f stops but include their own light source.

Rukmini Wilson

In reply to Paul Galburt | 05/30/14 01:48am

So, interestingly, the ideal security lens in any given situration is almost the reverse of the design of a photographic lens. (EA)

Interesting, yes, indubitable, no.

...most security cameras use other means to improve low-light performance.

First, although there may be 'other means' available to surveillence cameras, that's because low-light performance is so key to surveillence that other more artistic concerns, e.g. color space, low noise/distortion, are sacrificed if need be to that end. These are things that no photographic camera would dare do. 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, and a lot lower is a lot better.

Also, lower F numbers mean shallower depth of field (DOF).

This is true. However true DOF issues are rarely seen in security cameras. Why? Two technical reasons:

1) Sensor size smaller sensor = deeper DOF. 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 crap crop factor of 2. Main reason shallower DOF afforded by larger sensors.

2) The nominal distance to subject is usually large enough to render it imperceptible. We're not talking close-up portrait with blurry daisies in the background. Also, if the distance is small enough to show the effect, often it doesn't matter if the background is out. Like in an LPC system.

And regardless, it seems unlikely that the industry is choosing higher f-upped lenses because they fear shallower FOV's.

So I would say although there are differents emphasises and constraints on each discipline, the lens design concerns generally follow the same vector.

Avatar

Nick Ames

In reply to Paul Galburt | 02/23/17 01:11am

Well noted Paul. Coming from a photographic background, and now learning surveillance technology, it is often hard to grasp concepts that seem to be turned upside down. I try to look at it as a completely different concept, or I get into trouble, trying to apply what I thought I previously knew about photography to surveillance cameras/lenses. I do want to eventually try large sensor (35mm) surveillance cameras.

Avatar

Ng Choy Mei

IPVMU Certified | 05/09/18 11:36am

Seems that varifocal lens is more popular and flexible.

Avatar

David Johnson

05/09/18 05:45pm

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'.

Avatar

Brian Rhodes

IPVMU Certified | In reply to David Johnson | 05/09/18 05:54pm

Charlie Pierce is a legend! We did an interview with him a few years ago. See: Charlie Pierce: How Video Surveillance / CCTV Has Changed

Also, Charlie likes to give hugs. (He is a genuinely nice person)

Chin Liang Benjamin Lee

IPVMU Certified | 05/13/18 06:16pm

During previous installation, indeed many customers prefers to use vari-focal lenses due to the reasons mentioned above...nice sharing.

  • customers may want to increase ppf for certain situations and/or increase area of view depending on their perceived need
  • varifocal to allow our installers more freedom to adjust the fov/focal length to meet the customer preference

Charng Haw Guo

10/31/18 12:00pm

Simple yet easy to missed.

Login to read this IPVM report.
Why do I need to log in?
IPVM conducts unique testing and research funded by member's payments enabling us to offer the most independent, accurate and in-depth information.

Related Reports

8MP / 4K Fixed Lens Camera Shootout - Dahua, Hikvision, TVT, Uniview on Dec 17, 2018
8MP / 4K fixed lens models are now common in lower cost lines, with nearly every Chinese brand and their OEMs now offering multiple options. To...
Top 2019 Trend - AI Video Analytics on Dec 10, 2018
160+ Integrators answered: What do you think the top industry trend will be in 2019? Why? AI / video analytics was the run-away winner with...
Ubiquiti $79 Flex IP Camera Tested on Dec 07, 2018
U.S. Manufacturer Ubiquiti has released a 1080p, integrated IR IP camera, selling it directly for $79, making this one of the least expensive IP...
ADT Wins Fire Death Suit But Faces Appeal on Dec 05, 2018
ADT/Protection 1 has won a wrongful death court case in which it was sued by the estate of a deceased customer. However, the attorney for the...
Hanwha L Series Lowest-Cost Camera Tested on Dec 04, 2018
Hanwha has released their lowest-priced IP camera line ever, the L series, that competes on price with low cost competitors Dahua and...
ADT Promotes DIFY - "Do It For You" on Nov 30, 2018
"Do It Yourself" (DIY) is a popular expression and has become such a common word that it has even made the Cambridge English dictionary. But why...
Strong Outlook For 2019 on Nov 29, 2018
Integrators are bullish for 2019, with nearly 80% showing a positive outlook in our integrator results from 160+ respondents: This is almost...
Cybersecurity Insurance For Security Integrators on Nov 29, 2018
Most security industry professionals carry insurance to cover themselves in the event of a general loss. However, most are not carrying cyber...
HID Product Configurator Examined on Nov 26, 2018
HID is widely used. However, figuring out all the different configurations of features for a final credential or reader part number can be a real...
Top Manufacturers Gaining and Losing 2018 on Nov 26, 2018
This is the 5th year IPVM has tracked manufacturers gaining and losing: Top Manufacturers Gaining and Losing 2014 Top Manufacturers Gaining and...

Most Recent Industry Reports

Dahua USA Sales Team Cuts - 'Strategic Right Sizing' on Dec 18, 2018
Dahua USA finishes a tumultuous year in which it acquired the Flir SMB business, was subject to the US government ban, terminated and restructured...
This Brooklyn Storefont Sells Millions In Uniview And Hikvision on Dec 18, 2018
Looking at their Brooklyn headquarters for this "CCTV Manufacturer", it is not much: Inside, it is not better: However, this company is one...
ACRE-Acquired Open Options Access Company Profile on Dec 17, 2018
Who is the company ACRE is acquiring? In this note, we examine Open Options line for best customer fit, key features, pricing, and main...
Open Options Acquired By ACRE on Dec 17, 2018
ACRE is doing deals again. A year after they sold Mercury, they are buying another access control company - Open Options. In this note, we...
8MP / 4K Fixed Lens Camera Shootout - Dahua, Hikvision, TVT, Uniview on Dec 17, 2018
8MP / 4K fixed lens models are now common in lower cost lines, with nearly every Chinese brand and their OEMs now offering multiple options. To...
Network Cable Shootout - Belden, Commscope, Hikvision, Honeywell, NavePoint CCA, Windy City Wire on Dec 17, 2018
Every IP camera install needs UTP cabling. But how much of a difference is there between dirt cheap generic cables found online and the bigger,...
Hikvision Government Parent Holds Communist Party Congress on Dec 17, 2018
The Communist Party committee of Hikvision’s government parent, CETHIK, held a Party Congress earlier this month where senior executives, including...
Imperial Capital Security Investor Conference 2018 Review - ADT, Resideo, Alarm.com, Arlo, Eagle Eye, ACRE, More on Dec 14, 2018
Imperial Capital Security Investor Conference is an event matching industry executives with financiers that frequently leads to future funding...
Cisco Meraki New Cameras and AI Analytics on Dec 14, 2018
Meraki has released their second generation of video surveillance with 3 new cameras, AI-based video analytics, and 2 cloud-based storage...
Foolish Strategy: OEMing Facial Recognition on Dec 13, 2018
Almost as 'hot' as face recognition marketing right now is OEMing facial recognition. Last year, they were a who's who of company's with...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact