How to Select the Lens for Your Megapixel IP Camera

Lenses for Megapixel IP Cameras

What lens should I use for my IP Camera?  Determining the right lens can be complicated and assuring that you get the right one requires some care.  This is a very important part of your IP camera system.  If you get a megapixel IP camera but don’t get the right lens you are wasting your money. 

Many IP cameras come with lenses.  For example the Axis P1354 comes with a 3 mm to 8 mm lens (100° - 34° horizontal field of view).   How do you determine if this will actually work in a specific application?  First make sure you know what the angle or mm of the lens should be.  The higher the mm numbers the lower the angle and the more magnification you will get.  It’s best to use the lens angle that is provided by the manufacturer instead of the mm of the lens since the angle can vary based on the size of the sensor.  

Lens Angle 

By measuring the field of view and how far away the camera will be from the area you want to view, you can calculate the angle of the lens.  To calculate the angle of the lens required you need to use trigonometry.  Don’t get upset, I slept through this class in high school as well.  I do remember my teacher saying, “You’re going to need this someday”, and me thinking, “Yeah, right”.  There are some calculators on line that can make this job easier.  Here is a review of the basics.   

 First we want to use the horizontal field of view rather than the vertical field of view, so let’s image we are looking down on the camera.  We split the triangle in half to get a right triangle.    

Then we can use the tangent function to calculate all the dimensions and angles.

The tangent (angle) = Opposite / Adjacent

In this case the dimensions we use are ½ the field of view (FOV) and ½ the angle, so the equation is:

The tangent (½ angle of the camera lens) = ½ the FOV / Distance from camera to FOV

Now we can calculate everything we need.  For example if the distance to the field of view is 100 ft. and the FOV is 50 ft. Here’s how we get the lens angle:

½ Tan(lens°) = ½ 50 / 100.

 Tan(lens°) = 2 x(½ 50 / 100)

Now I go to my on line calculator at http://www.pagetutor.com/trigcalc/trig.html and enter 25 where it says “Side A”, and then 100 into the “side B”, I get 14.04°. 

Then 2 x 14.04° = 28.08°.  

And of course, if you know the lens angle and want to calculate the FOV based on a certain distance, you can do this as well using the same equation and calculator.  

OK, your head hurts.  I understand.  Just take two aspirin and call us and we’ll do all the calculations. 

Other Specifications

Once you know the type of lens required you also need to review all the other lens characteristics for a specific application.  We reviewed all the lens specifications in our technical article Megapixel Lens for Megapixel IP Cameras, but here is a summary.  

Lens Format or Size: the lens size should be larger than the sensor of the camera.

Lens Mount:  There are 2 types of mounting formats used in IP cameras, C and CS type.  Make sure the lens you select matches the camera mount.

Iris:  There are manual adjustable irises, auto-iris and the latest p-iris.  If the lens is used indoors, you usually can use a manual iris camera, but outdoors you need an auto-iris lens.  If there are challenging lighting conditions then the p-iris is a good choice. 

 If you are using a megapixel IP camera then you must consider some additional specifications such as lens resolution, depth of field, iris control, and distortion, aperture and IR light capability. These are all very critical to assuring that you get the video that you expect.  If you get an inexpensive lens you certainly won’t be happy with the video.  

Yes, this is all complicated so please contact us for assistance.  We will review your objectives and make sure that your complete IP camera system performs exactly as you expect.  Please call us at 914-944-3425 or just use our contact form. 

Authentication in Door Access Control Systems

Door Access Control Systems have been around for many years. Recently new technology has increased security by providing better authentication of the person at the door.  Before selecting your system, you should first determine the degree of security you need.  For example, the security level for an office building could be different from a secure military facility.  There is a tradeoff between cost, ease of use and security level provided.   Key-locks were the original method of controlling the door.  It has been around for thousands of years.  The key provided the authentication.  Since a key can be lost or stolen it is not as secure as using more sophisticated biometric authentication system.  Here is a review of the most common methods for authentication and the level of security they provide.

Keypads

Keypads are probably the least expensive, but also provide the lowest protection.  A PIN number can be forgotten or someone can see the key number entry.  There are two types of keypad systems, one that is included with the lock (sometimes referred to as keyless entry) and another type that includes a separate keypad and electric lock. 

The simple mechanical lock with keypad is primarily designed for home use but can also be used in a small business.  The problem with this system is that it doesn’t have the ability to contain unique numbers so it is difficult to control when there are many people using it.  If someone leaves the organization you have to change the number that everyone else uses. 

The separate keypad is used to control an electric lock on the door.  It is usually used with a central control box that stores an individual code for each person registered in the system.  This system can be used to control access on multiple doors, but it must be used correctly to assure security.  I have seen situations where organizations have issued the same number for everyone.  This type of situation provides very little security.   The database allows you to register each person, and assign the rules about when and where they can enter.  This is more secure but still has problems with stolen numbers and people having to remember the number. 

Card Access Systems

Instead of having each person remember a PIN number, you can provide cards that contain unique codes.  The early readers used bar code, magnetic strip or even Wiegand effect type technology.  

Today most card systems use some type of radio frequency connection and are more secure.  The cards have become credentials that include keyfobs and lanyard style cards and the number is encrypted.   

The latest door access control readers are attached to the network and use standard IP protocols just like computers on the network.  These IP door readers can handle a number of different types of credentials.  The latest “smart cards” not only include unique encrypted numbers but can contain information about the person who holds the credential.  Smart cards such as Mifare type credentials have been used in Europe to pay for transportation.  The credential has built in storage that holds the cash to be used for payment.    

Using credentials is a lot more secure than using a keypad, but there are some concerns about people losing their card or even of higher technology theft of identity using special electronic techniques. 

Security can be increased by adding IP camera systems.  This allows real time and recorded video to be monitored.  

Biometric Authentication

The latest method for authentication is to use a person’s key biometric factors such as fingerprints, voice identification and facial recognition.  This is probably the most secure form of authentication. 

Fingerprint identification:  This has been around for a number of years.  It has become more reliable and less expensive.  You may be familiar with fingerprint identification used by police to catch criminals.  This started out as a manual process but is now automated.  It uses specific characteristics of the fingerprint such as arch, loop and whorl patterns to recognize one print from another.  The same type of identifier is also used in automated access control systems.  Each person is registered in the system using their fingerprints.  The database in the access control system uses the results of the recognition circuits to create a unique pattern for each person.   This pattern can then be compared every time a person uses the system to enter the door. 

There are a number of technologies used to read the fingerprint such as optical, ultrasonic and capacitive.  Each method has pros and cons associated with it.  This system is very secure but there can be problems with reliability.  Dirt and scratches on a finger can deny entry.  

Facial Recognition:  These systems provide an easy way to authenticate a person.  They have gotten much better over the last few years, but there are still some issues with reliability.  For example, if a person comes to the door wearing dark glasses, the system may not be able to recognize them. 

To increase reliability some facial recognition systems have added other biometrics such as Body motion and voice recognition to improve performance.  FST21 Corporation is an example of a multi-modal biometric system that views people as they approach the door.  This provides a much faster analysis and allows people to move quickly through the doorways.  

 It is a challenge for all of us to select the best equipment at the best price.  With that in mind, we continue to review the latest technology from companies all over the world in order to increase our safety and security.   

Please contact us if you need help with your access control systems.  You can contact us at 914-944-3425 or use our contact form.

NVR, DVR, or Video Server?

By Virginia Fair

“Questions………we get questions”

Wasn't that a jingle on a popular TV show of the Sixties? (Seventies?)  Well it could be Kintronics' theme song, too. Our sales engineers get all kinds of questions when fielding calls.

 Today we’ll give you a hypothetical conversation that could occur any day. A caller wants to know what type of video storage device her business should use.

Caller: “What is the difference between a Video Server, a NVR, and a DVR?”

Video Server

Sales Engineer: The network video server is a computer that runs special Video Management Software known as VMS and is used to record video from IP cameras. A windows computer is usually the platform for the VMS, and video is recorded onto the computer’s hard drives in a special video format.

Sometimes people are confused by this term because a number of years back a device that attached an analog camera to the networks was also called a video or camera server. Now that’s known as a Video Encoder.

Caller:  Yes, I was confused by that myself. Now what about the NVR?

NVR

Engineer:  A NetworkVideo Recorder, or NVR, is a complete IP camera recording device. It includes a computer and special Video Management Software. VMS is required for recording video, but it also allows multiple viewers to monitor real time and recorded video.

Caller: I think I understand, but could you go over the differences between the Network Video Server and a Network Video Recorder one more time?

Engineer: Sure. The Video Server and Network Video Recorder are similar in that they both record video. The Network Video Recorder comes with the Video Management Software already installed.

 The Video Server does not include VMS. You select the software you like and load it.

The Video Server usually runs on a Windows operating system and it’s more flexible than the NVR because it is easier to expand and add cameras. The NVR, on the other hand usually has a fixed limit as to the number of cameras it can support.

Caller:  Okay, Got it. Now what about a DVR?

DVR

Engineer: The DVR or Digital Video Recorder is a device that records video from analog cameras to one or more hard drives. The term DVR is also used by the consumer TV market.

 The DVR used in the security market has a fixed number of BNC connections to attach cameras. DVRs are available with 4, 8, 16, 32, and 64 channels, or connections. This means that you have a maximum number of cameras that can be supported by one unit. Once you exceed the number of connections available on that particular DVR, you will need to add another DVR to your system.

 There are some DVRs that can connect to the network, and be viewed using a Windows computer.

Caller: Uh-huh, so what’s difference between a DVR and a NVR?

Engineer: There are several differences but let’s start with these:

• The NVR connects to the computer network along with the IP cameras. So you can take advantage of the existing network infrastructure, meaning you don’t have to run wire from a home base location.
• The DVR uses coaxial connections to each of the analog cameras.
• The NVR supports high resolution megapixel cameras
• The DVR supports only cameras with VGA resolution

Caller: Do they all let me store pictures on my hard disk for later viewing?

Engineer: Always with a NVR, and with the Video Server and DVR, as long as you’re using VMS.  Also, if you’re using VMS on your Windows compute, you can usually distribute the storage across a number of different hard drives on your network. It depends on the VMS.

But no matter which VMS you use, storing images every second, around the clock means storing a lot of pictures that are exactly the same. So you’re using valuable space to no avail. One way around that is to have a motion detector starting and stopping the recording. Another space-saving alternative is to reduce your frame rate.

Caller:  Okay, let’s talk about this software. What do I need?

Engineer:  There are a number of VMS products out there. The main job of any Video Management Software is to record the video from many IP cameras on the network. It is very important to select software that’s reliable and doesn’t crash. Imagine how you’d feel if you lost important video. It’s also important to use a dedicated computer system to run the software.

The various VMS products available have many additional functions, including motion detection, sending special alerts to tell you if something important has happened, flexible displays of real time and recorded video, easy location and display of multiple recorded video channels. The features you choose depend on your particular objectives.

Caller: Do I need a network switch?

Engineer:  Yes. You may have to add a network switch if you don’t have any empty ports on your current switch, or if you don’t have a network switch installed. You require one port for each camera.  It’s best to use a network switch that includes PoE on all ports.

Caller: PoE? What’s that?

Power Over Internet (PoE)

Engineer:  The latest IP cameras get power over the network. This is known as Power over Ethernet or PoE. You can also add a PoE midspan, or a power injector between the switch and the camera.

Using PoE means you only need to run one network cable to each camera. That makes installation so much easier.

Caller: How about a video switch? Will I need that?

Engineer: No. The LAN network switch operates as the switch allowing hundreds of cameras to be viewed on a network.

Caller: Wow, Let me run this past my boss and I’ll get back to you as soon as we figure out which will serve us best.

Engineer: Would it help if I send you some specification pages and data sheets to help with your decision?

Caller. That would be great. Thanks so much for all the information?

Do you have any questions? Do you need clarification for any of the answers here? If so, our sales engineers can provide you with all the answers you need. They can also help you with IP cameras, Door access control, and IP paging systems. Call us at 914-431-1658 or fill out a request information form at http://www.kintronics.com/RequestInfo.htm

Virginia can be reached at virginia@kintronics.com

Viewing Your IP Cameras on Your Smart Phone

Recently there was an article in the IEEE technical journal that declared, “Video Telephony has Finally Arrived”.  They described how the Jetsons first predicted this in 1962, and now we can use our computer and Smartphone to do exactly what George did with his boss Cosmo Spacely.  This animated sitcom described the world in 2062.  I guess we did this sooner than expected. 

To make the video phone a reality a number of obstacles had to be overcome including cost of the video equipment, the cost of high speed connection, and better compression schemes.

Now what about viewing our IP surveillance cameras remotely?  Does the new technology allow us to view all our surveillance cameras at home or on the road?  Well almost.  When we use our Smartphone’s to see each other, we are usually just looking at a person’s face.  If we try to view a wider area, say the complete room, things are not that clear.  The video we see on our Smartphone has less resolution than that usually required for surveillance.  Because we would like to see a lot more detail for our surveillance applications we require much higher resolution and a better display.  A computer is still the best way to view your remote IP cameras.
 
Viewing an IP Camera using your Smartphone
Let’s look at the complete communication channel required to get the video from our cameras to our cell phones or even to a remote computer.  You can picture the components of the system as a set of water pipes connected together.  The bigger the diameter of the pipe the more water can flow.  The smallest diameter pipe will determine how much water flows through the complete system.  There are basically 4 components to the system. 
1)      First is the IP camera.  It needs to compress the video so that it uses as little data as possible to see the video without reducing the resolution. 

2)      Second the outbound bandwidth available at our cellular modem must be high enough to handle the data flow we need.

3)      Third the phone company cellular system must have enough bandwidth.

4)      Finally the Smartphone has to have good enough performance to support the latest cellular services and be able to display the video.

For example, if the bandwidth from the IP camera is 1000 K bits/sec but the cellular network bandwidth is only 200 K bits/sec. the maximum bandwidth through the complete system is limited to 200K bits/sec. 

Compression
The first IP cameras used MJPEG compression, and this is still the best compression for viewing the video on your Smartphone.  Today the new H.264 compression dramatically reduces the bandwidth required for an IP camera.  It reduces the bandwidth and the storage required over a factor of 10X. For example, a VGA camera (running at a frame rate of 20 fps), using MJPEG compression, requires about 4.8 Mbits/sec, while an IP camera using H.264 compression would require less than  400 Kbit/sec.  This compression scheme is dependent on many different factors including the amount of motion detected, so it is possible to use a lot less bandwidth. Take a look at our article about the Latest H.264 Compression for more about this.

Cellular Network
One of the limiting portions of the communication channel is the cellular network.  This is usually the smallest pipe in the system.   3G networks provide a maximum of about 200K bits/sec bandwidth.  Since Smartphones do not work with H.264, there is a lot more bandwidth required for MJPEG.   Since we require 4800 Kbit/sec (using MJPEG compression) to see the video running at 20 fps, we will see a lower frame rate at our Smartphone because of the cellular bandwidth limitation.  In this case, we will get about 1/24 the frame rate or less than 1 fps at the phone.

 4G networks promise to increase the bandwidth to 1 Gbits/sec.  This should allow us to support higher resolution cameras.    I say it should work, but the reality is that cell phone providers need to share bandwidth with all the available users.  They will throttle the bandwidth used by that camera location whenever many people try and use the same tower connection.

Another important aspect of using cellular systems is the cost of the cell service.  You will have to purchase a data package from your local cell phone provider.  There are sometimes limitations to the bandwidth that they will provide.  

Viewing Many Cameras on Your Remote Computer
 When we use a remote computer that’s attached to the internet, there are four things to consider, the compression from the camera, the outbound Internet connection, the Internet speed and the inbound Internet connection.

Many Internet connection companies provide good inbound bandwidth but much less outbound bandwidth so always check.  The outbound Internet bandwidth can dramatically affect the frame rate you can see.  If your provider only gives you an outbound bandwidth of 512K Bits/sec, you will see a much lower frame rate at the remote viewing point. 

The best way to view multiple cameras is to utilize a viewing client that comes with Video Management Software (VMS). This also allows you to view recorded video as well as the real time video.  Ocularis from OnSSi provides an excellent client viewer, while TruViewIP provides a good web client as well as a Smartphone interface.  The bandwidth to the remote viewing client depends on the total number of cameras you are trying to view, so the total bandwidth through the system available becomes very important.  If you have a limited bandwidth at any point in the system, you will see reduced frame rates.

Summary
Some of the same technologies used by our Smartphones to create a video presence are used by our IP camera systems. You can view IP cameras using your Smartphone, but you can’t expect full frame rates because of limited bandwidth through the cellular phone system.  To view recorded video or and view multiple cameras you will need Video Management Software.  You will also need more bandwidth when you view multiple cameras.

If you need help figuring out the best solution for your application, please contact us at 1-800-431-1658 or 914-944-3425 or use our contact form.