Training: Using Lens Calculators

Author: John Honovich, Published on Sep 27, 2010

In video surveillance applications, lenses generally take a 'back-seat' to their sexier camera counterparts. However, selecting a proper lens for an application helps ensure the highest quality image. Specify a lens too narrow for your application and one will miss out on capturing the entire area of interest. By contrast, a lens that is too wide will result in poor video quality of the subjects monitored.

A lens calculator can determine the appropriate lens focal length required for a desired field of view and therefore optimize system performance.

Key Concepts

Before using any lens calculator tool it is important to understand a few key concepts:

  • Sensor Size or Format - Cameras have an imaging sensor that comes in a variety of sizes, such as, 1/4", 1/3", 1/2.5", and 1/2".  Calculator tools usually provide a means to select one of these values for the calculation. This sensor size or format is easily determined by looking at the specifications sheet of the camera being considered. Note that whether the sensor is a CCD or CMOS has essentially no bearing on calculations.
  • Focal Length (mm) - Lenses generally fall into two categories: fixed focal length and vari-focal length lens types.  The focal length is essentially the distance between the lens and the imaging sensor. This distance determines how wide or narrow the scene captured will be. Shorter focal lengths are able to capture relatively wider scenes, while longer focal lengths provide tighter viewing angles for capturing more distant objects.  Vari-focal lenses have the advantage of providing a range of focal-lengths for added flexibility and control.
  • Horizontal Field of View (FoV) - The horizontal field of view (HFoV) is probably the most practical and well recognized property of the camera/lens system. It represents the width in units of length (feet or meters) of the camera scene at a specified distance from the lens.  This is a measurement typically obtained first-hand, perhaps during a site survey. It can also be theoretically calculated given a 'distance from lens' parameter and a 'lens angle' parameter.

IPVM Calculator

IPVM has the industry's best camera / lens calculator. Try it out here.

Learn how to use it below:

** ***** ************ ************, ****** ********* **** * '****-****' ** their ****** ****** ************. *******, ********* * ****** **** *** an *********** ***** ****** *** ******* ******* *****. ******* * lens *** ****** *** **** *********** *** *** **** **** out ** ********* *** ****** **** ** ********. ** ********, a **** **** ** *** **** **** ****** ** **** video ******* ** *** ******** *********.

* **** ********** *** ********* *** *********** **** ***** ****** required *** * ******* ***** ** **** *** ********* ******** system ***********.

Key ********

****** ***** *** **** ********** **** ** ** ********* ** understand * *** *** ********:

  • Sensor **** ** ****** - Cameras have an imaging sensor that comes in a variety of sizes, such as, 1/4", 1/3", 1/2.5", and 1/2".  Calculator tools usually provide a means to select one of these values for the calculation. This sensor size or format is easily determined by looking at the specifications sheet of the camera being considered. Note that whether the sensor is a CCD or CMOS has essentially no bearing on calculations.
  • Focal ****** (**)- ****** ********* **** **** *** **********: ***** ***** ****** and****-*********** **** *****.  *** ***** ****** ** *********** *** ******** between *** **** *** *** ******* ******. **** ******** ********** how **** ** ****** *** ***** ******** **** **. ******* focal ******* *** **** ** ******* ********** ***** ******, ***** longer ***** ******* ******* ******* ******* ****** *** ********* **** distant *******.  ****-***** ****** **** *** ********* ** ********* * range ** *****-******* *** ***** *********** *** *******.
  • Horizontal ***** ** **** (***)- *** ********** ***** ** **** (****) ** ******** *** **** ********* *** **** ********** ******** of *********/**********. ** ********** *** ***** ** ***** ** ****** (**** or ******) ** *** ****** ***** ** * ********* ******** from *** ****.  **** ** * *********** ********* ******** *****-****, perhaps ****** * **** ******. ** *** **** ** ************* calculated ***** * '******** **** ****' ********* *** * '**** angle' *********.

**** **********

******* ***********'* **** ****** / **** **********. *** ** *** ****.

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

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

Basic **** ********** *****

** **** *****, ** ***** *** ******* *** ***** ***** of * ************** **** ****** ********** ****. ** **** * quick **** ** *** **** ********** ********* *** ********* **** key ***** ******. ****, ** ****-******* * *** ***** ******** to ****** ********** ***** ** *** ********** ****. ***'** *** a ****** ******* ** *** **** **** *********** ******* * reference ***** ***** ** *** ***** **** *** ****.  **** gives *** **** * ****** ***** ** *********/********** ***** **********.

 FoV ********

** **** *****, ** ******* * ********** *********** ** *** field ** ***** (****) *** *******. ***'** ***** **** **** are ********* ** ********** ** *** ****** (****** ****), ********** of *** **** (***** ******) *** *** ******** **** *** lens ***** **********.  ** *** * ******* ** ******* ********** why * ****** ****** **** ******* ** * ***** *** for *** ***** **** ***** ******.

Pixels/Foot ******** *** ***********

** **** *****, ** *********** **** ******** ** *** * lens ********** **** ***** ** **** ** * **** ********** video ************ ****** ********. **'** ******* *** ******* ******** ******** in *** '******' ***** *** ***** ****** **** *** ****'* ability ** ******* ***** ********** ********/******* * ***** ***/**** ********** *** ********** ***. 

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 on Lenses

Dahua 4K IR PTZ Tested on Aug 21, 2017
4K has made its way to IR PTZs. In this report, we examine the Dahua 6AE830VNI, a 4K PTZ with 30x optical zoom, 200m (~650') integrated IR, and...
IP Camera Specification / RFP Guide 2017 on Aug 14, 2017
RFPs are hard. Do them 'right' and it takes a lot of knowledge and time. Do them 'wrong' and you can be (a) unwittingly locked into a specific...
Technician Personal Protective Equipment (PPE) Guide on May 12, 2017
Technicians encounter multiple hazards when running wires and installing security devices. Wearing personal protective equipment, or PPE, helps...
Varifocal Vs Fixed Lens Statistics 2017 on May 04, 2017
Varifocal camera lenses provide more flexibility at installation time, but come at a higher cost. Fixed lens cameras reduce hardware costs, but can...
Hikvision PanoVu Multi Imager Tested on Feb 08, 2017
Hikvision has entered the multi-imager market with their 180° PanoVu DS-2CD6986F-H, an 8MP, 4-imager model equipped with ~1/1.8" imagers and...
Avigilon Pro 4K Camera Tested on Jan 03, 2017
Avigilon is best known for their large sensor, high megapixel cameras. But with new offerings from Sony and soon Axis, the questions is how well...
Lens Iris Tutorial on Dec 19, 2016
Cameras, like humans, have irises. However, cameras have five types of iris options - fixed, manual, auto, P iris. In this tutorial, we explain the...
F-Stop Tutorial on Dec 16, 2016
To understand low light surveillance, appreciating the importance and role of the f-stop metric is critical. In this tutorial, we explain: Why...
Genetec Lower Cost Sharp V LPR Camera on Nov 23, 2016
Genetec has announced the latest offering in their AutoVu Sharp line, promising new features, simplified installation, and lower price. In this...
Testing EF Lenses On IP Camera on Nov 23, 2016
Glass. IP cameras are often characterized as using lower quality 'glass' and that those lenses reduce image quality. By contrast, Canon EF lenses...

Most Recent Industry Reports

Nest Secure Alarm System Tested on Nov 16, 2017
Google's expansion continues, this time into home security with their Nest subsidiary's move into alarm systems. They paid more than a...
Dahua Forbes 'Next Web Crisis' Vulnerability Dispute on Nov 16, 2017
The buffer overflow vulnerability in Dahua products is not in dispute, in fact we covered it when it was first published. What is in dispute is...
Isonas Cofounders Split, Launch Partner/Competitor on Nov 16, 2017
Breaking up is hard to do, especially when door access security is at stake. But that is exactly what has happened at Isonas. Senior employees...
Hikvision China Criticizes The WSJ on Nov 15, 2017
Hikvision, through the Chinese government's authoritative news service, has criticized the WSJ investigation into Hikvision. In this...
PoE UPS Tested (Energy Reconnect) on Nov 15, 2017
In security, backup power is important, but most often requires UPS systems or extra cabling to devices for low voltage power. Now, some have...
Axis Commits To Long-Term Firmware Support on Nov 15, 2017
With the rise of cyber security awareness, and a general increase in hardware reliability, "software warranties" may prove more valuable than...
Hikvision NVR 4.0 Improvements Tested on Nov 14, 2017
Hikvision has released firmware version 4.0 for select NVRs, touting two years of research and development, and claiming "the new generation GUI...
Mobile Credentials (BLE / NFC / Apps) Guide on Nov 14, 2017
One of the biggest trends in access for the last few years has been the marriage of mobile phones and access cards. In this guide,...
Dahua Launches Electric Cars on Nov 13, 2017
Embattled mega video surveillance manufacturer Dahua is now electric car manufacturer Dahua. Let the jokes begin: But is the joke on Dahua's...

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