Sunday, April 20th, 2014

The frequently asked questions for security camera


Why can’t thermal and infrared cameras see through glass?

Thermal cameras and Infrared cameras operate in wavelengths just above visible light. These wavelengths are a part of the electromagnetic spectrum and are all closely related. As temperature increases the wavelength decreases. This is why when something gets hot enough it glows in the visible spectrum and we can see it with our eyes.
The visible spectrum is about 280nm (nano meters) to 750nm (nano meters). Very near infrared light that is used in infrared lasers, camcorder night vision and IR remote controls is in the 800-900nm range. This very short wavelength infrared energy can indeed go through glass. You can see this by using your tv remote control through a glass window and obviously it will work.

Difference between H.264 and MPEG 4 encoding format.

MPEG-4 is a standard used to compress audio and visual data. The MPEG-4 standard is generally used for streaming media and CD distribution, video conversation, and broadcast television. MPEG-4 incorporates many features of MPEG-1, MPEG-2 and other related standards.

H.264 standard is jointly maintained with MPEG so that they have identical technical content.
The intention behind H.264/AVC project was to provide good video quality at substantially lower bit rates than previous standards. An additional goal was to provide enough flexibility to allow the standard to be applied to a wide variety of applications on a wide variety of networks and systems.

Whether you are choosing a Varifocal Lens, or a Fixed Lens, there are a few terms that are important to know to help you make your decision. Every Security Camera can have different requirements for a Camera Lens.
Focal Length
The Focal Length is measured in mm. As a guide:
a short focal length (e.g. 2.5mm) = a wide angle of view
a long focal length (e.g. 16mm) = a narrow angle of view

Depth of Field
The Depth of View is the distance within which objects in a picture are in focus.
A large Depth of Field means almost all objects in the Field of View are in focus.
A small Depth of Field means only a small section of the Field of View are in Focus.

F Stop
F Stop – is the lenses ability to gather light depending on the aperture and focal length.

CS or C Mount
The 2 standard CCTV camera lens mounts. The difference between the two is simply the distance between the lens and the CCD image sensor.
C Mount – 17.5mm
CS Mount – 12.5mm
All of our CCTV Lenses can be configured for use as CS or C Mount

Manual or Auto Iris
For changing light conditions (e.g. cameras positioned outdoors), Auto Iris lenses are needed.
For indoor use, manual iris lenses are sufficient, as light levels will not vary too much.

What is the Difference Between an IP Camera, Network Camera and Internet Camera?

The name IP Camera is starting to become more common than the name Network Camera. Most manufacturers refer to their products as IP Cameras and because of this, most customers looking to buy these products refer to them as IP Cameras. Some people even mix the term IP Camera with Network Camera to call it an IP Network Camera. This is the term I like to use as well.

The name Internet Camera. The main camera manufacturer that uses this term is D-Link. They refer to their cameras as Internet Cameras because the camera can be configured to be viewed over the Internet from any remote location. As you probably know, that is one of the main benefits of using these cameras. The term Internet Camera is not widely used as the other two terms but it still describes the product to a tee.

The name Network Camera is one of the most common names for these products. The name simply describes how their products work by connecting to a computer network allowing all PC’s and network devices to see the camera.

What is the difference between 420 TVL and 480 TVL security camera resolutions?

The difference is 60 lines of resolution. Commonly you will see 380, 420, 480 and 540 resolution options on standard CCTV security cameras. 420 cameras are fine to be used in some locations if you are not wanting that much actual detail. It would be much better to go with a 480 or even all the way to 540 TVL. There are many lower cost cameras manufactured in China that have 420 TVL.

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