Posts Tagged ‘ varifocal lens’

What are Varifocal Cameras and Varifocal Lenses?

Written By:
Wednesday, November 12th, 2014

700 TVL Outdoor Varifocal Bullet Security Camera

So you’re looking for the right cameras to purchase when setting up your home or business surveillance system, and you begin to see all these different terms of tech talk. You wonder to yourself, “What are Varifocal Cameras and Varifocal Lenses?” It’s actually pretty simple to understand but finding the right one for each one of your scenarios may prove to be a bit more difficult. However, with this article, it doesn’t have to be! I will try my best to explain all of the details of Varifocal Cameras and Varifocal Lenses starting with the meaning of a lens or camera being Varifocal and why you would need a Varifocal camera or lens. I will also discuss some of the different lengths of Varifocal available, and then help you understand the basics so that you can decide when to use one, whether or not you’ll need it over a fixed lens, and how to choose the right Varifocal lens for your security system if you decide it’s the right choice for you.

A Varifocal camera will allow you to adjust the lens to different zoom lengths and focal points. The word comes from Variable and Focal combined. Variable meaning that the value can change within the scope given, and focal meaning the focal point or length of the objects in the scene that you are capturing with your surveillance camera. Another easy way to explain it that most people understand right away is comparing it to a digital SLR camera. You can manually rotate the zoom ring on the lens in order to get a closer cropped shot of your subjects and then you may manually adjust the focal ring in order to put that object or person into more of a clear perspective. Normally a DSLR Lens will allow you to set the auto focus but most Varifocal security cameras are going to be fully manual so that you can set the lens to the correct zoom and focal point and then leave it that way after mounting the camera and setting it up in the location of your choice. Also, these Varifocal lenses are not interchangeable like they are on a digital SLR camera. So when you purchase your Varifocal camera, you will have a choice of different focal points and zooms depending on how many millimeters are listed on the lens. Normally, you’ll see something like “2.8-12mm Varifocal Lens” on the description of a camera. This means that you’ll have the choice of setting the lens at a distance anywhere from 2.8mm to 12mm away from the camera’s image sensor where the image is formed. When you have the lens set to 2.8mm there is also going to be 2.8mm distance between the lens and the front of the camera where the light is focusing.

“Why would I need a Varifocal Camera or Varifocal Lens,” you ask yourself. Well, there are a few reasons that come to mind. First, having a Varifocal camera will give you a ton of flexibility when deciding on where to mount the camera and will allow you to have the option to move the camera later to almost anywhere you decide to put it. A Varifocal lens will give you the option to shoot down a drive way by zooming in all the way if you decide you just want to have a camera fixed on your new sports car. Or maybe you want to put a camera in a small room, and a fixed lens is not allowing you to capture everything you would like in that space. A lot of the times Varifocal lenses are rated at 2.8mm which is more of a wide angle view than the standard 3.6mm lenses on most fixed lens cameras. When zoomed all the way out to 2.8mm you’ll have a viewing angle of about 109˚ horizontal, 82˚ vertical, and 136˚ of a diagonal view. If you would like to view all of your choices in camera viewing angle we have set up an awesome lens chart that lets you see all of the distances and angles for cameras with a 1/3” CCD Chip.

A Varifocal Camera and Varifocal Lenses are usually going to cost more than the standard fixed lenses, but most people prefer to have them because of the flexibility you’ll have. They are just as easy to install as the fixed lens cameras are, but the only extra thing you’ll have to set during installation will be the focal point of your lenses. Here are some images of Varifocal cameras so you can see the various ways to adjust them:

Box Cameras

Most of these types of cameras do not come with lenses. You can purchase the Varifocal lenses separately. These are normally c-mount lenses which you can choose the right one for your application. These are one of the only types of surveillance cameras which are flexible with allowing you to choose the correct Varifocal lens for your needs.

1000TVL Box Security Camera
1000TVL Dual Voltage Box Camera

Megapixel Varifocal Lens

Even Megapixel IP Box Cameras will use varifocal cameras. However, you need to make sure to purchase the lens that is specifically made for this type of camera because the analog c-mount lenses will not work properly with the megapixel IP box cameras.

Megapixel Lens for IP Box Secuirty Camera
3.3-12mm Megapixel IP Camera Varifocal Lens

Varifocal Bullet Security Cameras

Bullet security cameras are also known as cylinder surveillance cameras and have a great design for easy mounting and weather resistance. They are normally the choice for cameras that are going to be mounted in a high out-of-reach area outside of a building. The varifocal lens on most of these cameras will allow you to zoom in close to get better detail on an area or you can keep it zoomed all the way out for a wide angle. The camera shown below have two large screws on the bottom for focusing and zooming. You may use a flat-head screw driver or a coin to set the varifocal on these models.

IP Long range Bullet Security CameraLong Range Bullet Zoom and Focus
2MP Varifocal Bullet Security Camera

Varifocal Vandal Dome Security Cameras

Vandal domes are great for protecting your home or business. These vandal domes can be installed indoor or outdoor and have a weather and vandal resistant dome. They can usually take a decent amount of impact from a vandal and the way their enclosures are designed, most of them make it very difficult for anyone to adjust their settings once they are mounted. Some of the better built vandal domes have the Varifocal screws inside of their protective housing and a vandal would need to take apart the camera in order to mess around with the focus or digital on screen display (OSD) settings.

700TVL Night Viewing outdoor dome camera
700TVL Infrared Day or Night Varifocal Vandal Proof Dome Security Camera

700TVL Night Viewing outdoor dome camera with dome removed
Inside of an Indoor or Outdoor 700TVL Varifocal Vandal Dome Security Camera

Last but certainly not least, there are some things to be aware of when shopping for cameras that have the ability to zoom and focus. There are Pan Tilt Zoom (PTZ) cameras available too which have optical lenses that are capable of zooming in and out and auto-focusing paired along with a motor that will pan the camera up, down, left and right in order to capture a full 360˚ view around the camera. These cameras are usually at least double the price of what you can get a Varifocal lens camera for, and depending on the application, a PTZ camera may be overkill. Many people may think that it’d be fun to have a PTZ to play around with but the reality is that it may not be needed. Also, you’ll need to have a DVR which has the ability to remotely control the camera, otherwise you’ll also need to spend extra money on a controller. Also note that the image sensor size on the camera will affect the view. If you test with the same exact lens, a camera with a larger image sensor will capture a wider viewing angle and will capture even more light which is great for situations where you may have low light. Be careful and do some research when purchasing your camera because some manufacturers and resellers will list their camera with the wrong chip size. They may list the camera as having a 1/3 inch CCD when the reality is that they have a 1/4 inch. This will cause your view to have a much narrower viewing angle. The main thing to remember is that having a larger image sensor is going to not only be great in capturing more light, but also having a sharper image and more vibrant color saturation when compared to another camera which may have a small image sensor. Sometimes you’ll see a very large camera with a small image sensor, so do not judge the size of the camera and expect it to have a certain size sensor in it without doing the research first to make sure what you’re getting.

I hope that this article helped you in learning and choosing the right camera for you. If you have any questions or concerns, always feel free to leave a comment below and we will help you with anything you may need. We also have an awesome forum with techs that answer pretty quickly!


PTZ-TOOL Programming Module

Written By:
Thursday, April 14th, 2011

The PTZ-TOOL programming module makes programming PTZ cameras a cinch.  Security Camera King offers this for sale for customers because there are many people that have more than 1 PTZ (Pan-Tilt-Zoom) camera in their system.  In fact, this tool is only required if you use more than 1 PTZ camera in your system, but it can be used to control a standalone PTZ camera as well.

PTZ cameras make for a powerful addition to a digital video security system.  Often times, these cameras can take the place of two or more stationary cameras making them very cost effective as well.  These cameras usually come with factory pre-settings and it may be useful to “tweak” them a bit; that’s where the PTZ-TOOL programming module comes in.

Before we talk about the PTZ-TOOL programming module itself, let’s take a look at what makes up a digital video system and exactly what a PTZ camera can do in that system.

A basic digital video security and surveillance system normally consists of three components; one or more digital video cameras, a Digital Video Recorder or DVR, and one or more monitors (a monitor is needed for the initial setup of the system, but once the system is up and running a monitor is actually an optional choice).

The cameras’ primary function is to “capture” video images created by light that reflects off objects in the cameras’ field of view.  The lens focuses this light onto a small sensor that ranges in size from 1/4″ up to about 1/2″ square.  When light strikes its individual units (pixels for example) the sensor produces an electrical impulse that can be measured.  These electrical impulses are used to create a video image that can be displayed on an electronic monitor and/or compiled into a file that can be stored on the DVR’s hard disk drive.

There are many different ways to increase or decrease the field of view for the camera.  One way is to use a varifocal lens.  These lenses however are often only manually operated and can only enlarge or reduce the field of view.  Another way to increase security coverage is to use more than one camera in such a manner that their fields of view overlap just a little.

The third way to increase coverage is to use a PTZ camera. A PTZ camera can normally pan 360 degrees or a full circle and have a vertical movement of at least 180 degrees.  In other words, picture an object that looks like a sphere cut in-half.  Now imagine the camera lens in that half-sphere; generally this is the area that the camera lens can move/rotate through in order to capture video images.

PTZ cameras have become very popular, due to their extreme versatility and advanced electronically controlled features.  However, there are so many different features and functions that it may seem somewhat overwhelming to the do-it-yourselfer.  The PTZ-TOOL Programming Module helps to make the task of changing PTZ settings easy.


The PTZ-TOOL Programming Module is designed for use with Security Camera King’s PTZ-LX550L3X Pan/Tilt/Zoom Camera and our PT-LX540 Pan/Tilt Camera.  If you use more than one PTZ-LX550L3X or PT-LX540 Pan/Tilt Camera you will need the PTZ-TOOL programming module.  One of the reasons that this tool is required when using more than one PTZ or PT camera is so the address of the camera can be changed from the setting of “1.”

The DVR has virtual “ports” that are assigned to the cameras to keep them separate for the DVR’s sake.  These virtual ports or addresses can range from 0-255.  Programming the camera to a different address allows the DVR or other device to control that camera only.  It’s the equivalent of a first name when talking about someone in a particular family.  If you used the surname only, no one would know who you were talking to; mother, father or siblings.  However, when you use a first name, then the individual knows exactly who you are talking to (addressing).

With the Programming Module for PTZ-LX550L3X and PT-LX540, you can assign different addresses (first names) to the cameras so that the DVR can keep track of them.

If you have any additional questions about the Programming Module for PTZ-LX550L3X and PT-LX540 contact one of our security experts today either by on-line “Live Chat” or by telephone at 1-866-573-8878  Monday through Friday from 9AM to 6PM EST.