Video Security Cameras Guide

a How-To Guide by Home-Security-Plus.com

How to Choose Video Security Cameras

High quality video security cameras are becoming more affordable than ever before. Even though some individual components have increased in price due to part shortages influenced by the Japanese tsunami, overall surveillance system prices continue to improve.

For under $200 today, consumers can obtain a CCTV security camera with a high resolution picture, DSP circuitry to improve pictures under low light levels, and excellent night time vision with infrared distances of over 100 feet.

Consider the IR515. This camera provides up to 165 feet of night vision, has 540 TV lines of resolution, a 2.8-12mm Vari-Focal lens, a 1/3 inch Sony Super HAD Color CCD II chip and also a Sony Effio-E DSP.

But what do these features and specifications mean? Is a lower cost camera without these features a better choice for some applications? This article is intended to address these issues.

We suggest that the reader review this article, take a look at the online catalog at www.home-security-plus.com or www.home-security-plus.com, and then give us a call at 866-685-6409 to assemble a system that best meets your home or business needs.

Fixed vs. Vari-Focal Lens

A good place to start a discussion of video surveillance cameras is the choice of a fixed focus versus a Vari-Focal lens. Fixed lenses have the advantage of being simple to install, and have relatively lower costs. Thus, many customers opt for a lens with a focal length that is typically optimized to a wide angle, such as 3.6mm.

These photos illustrate 4.3, 6, 8, 12, and 16 mm lenses. These pictures were taken with a tripod 10 meters from an office door in the U.K.

4.3 mm

6 mm

8 mm

12 mm

16 mm

Source: i-Catcher.co.uk

There are also formulas to determine the exact lens, based on the size of the chip in the camera, where the camera is mounted, and the desired field of vision. This chart from www.home-security-plus.com is based on the 1/3 inch lens, which is typical for the CCTV industry.

However, for a slightly higher cost the customer can consider a Vari-Focal lens. The lens can be manually adjusted at the time of installation to provide the optimal field of view for the application. We highly recommend this option in order to best fit the needs of the customer.

Lines of Resolution

Another consideration is the lines of resolution for an analog signal. Our cameras typically start at 420 or 480 TV lines of resolution, and can go up to 700 lines of resolution. These specifications all exceed the typical resolutions of traditional broadcast TV, which has about 330 lines of resolution. In our view, all of our models provide a very fine signal. Of course, more resolution is often a preferred choice. Many of our customers report that a 700 line analog signal can approach the visual quality of a 720p HD signal. With the high quality recordings provided by our DVR systems, when possible we recommend camera with visual quality of 540 TVL or above.

One trade-off that should be considered is how important is it to monitor a signal live compared with replaying the signal from a DVR (digital video recorder). Our DVRs provide recording resolutions measured as CIF and D1 (also known at 4CIF). Our high end units can record the high resolution D1 signal at full frame rates of 30 frames per second, so that motion is fluid. The lower level machines can record a very nice CIF signal at 30 frames per second, but have lower frame rates at the D1 resolution (typically 6-8 frames per second). However, CIF resolution signals record in highest quality mode at 30 frames per second look very good according to most of our customers.

CIF 352 x 240
2CIF 704 x 240
D1 704 x 480

IP Cameras vs. Analog

If the customer wants a true 720p equivalent signal, then most likely they will want to consider changing from analog technology in the video surveillance system to IP technology. A 1.3mp camera outputs a signal roughly equal to 720p; and a 2-3MP camera is roughly equivalent to 1080p HDTV.

In an analog system, the intelligence is concentrated in the DVR. This creates an easy to use and set-up system. In an IP system, the cameras themselves are intelligent. There are many ways to capture the video, and the solution becomes more of a computers systems solution. The user must also consider bandwidth availability, and storage availability. In short, an IP camera system, when specified, installed, and operated optimally can provide an excellent monitoring solution. It is also relatively easy to end up with a system that provides jerky or choppy signals that is difficult to operate, and consumes more computer system and hard drive resources than the casual user had anticipated.

Lighting Considerations

Almost all of our cameras use high quality chipsets from Sony (and occasionally Hitachi, Canon, or Panasonic). These chips are designed to provide a high quality picture across the entire visual frame and in the case of outdoor cameras when operated continuously under severe weather conditions. This is a very different design specification than for traditional snapshot cameras and cameras used for recording video in shorter segments (such as for movies).

Most cameras today are designed to provide good quality pictures even in relatively low lighting conditions. Inevitably, at some point ambient light is not sufficient to provide a good picture. At this point, cameras switch to infrared monitoring. Using light waves slightly lower in frequency than can be detected by the human eye, night vision is achieved without creating an unsightly light source. Please keep in mind that infrared pictures are black and white. The infrared sensors can be impacted by bright nearby lighting, and reflections from windows and snow.

Here is a chart to aid in understanding how to reading lighting specifications of surveillance cameras.

Typical light levels are:

Full Summer Sunlight: 50,000 Lux
Dull Daylight: 10,000 Lux
Shop/Office environment: 500 Lux
Dawn/Dusk: 1 - 10 Lux
Main Street Lighting: 30 Lux
Side Street Lighting: 0.5 - 3 Lux

Typical Lux for CCTV Cameras:

Low-cost cameras: 1-2 Lux
Standard cameras: 0.1-1 Lux
Low light cameras: 0.01-0.1 Lux
Super low light cameras: 0.0001-0.01 Lux

A good rule of thumb is to specify a camera to work with 5-10 times the specified minimum illumination. For example, if only 1 lux is available, choose a camera that goes down to about 0.1 or 0.2 lux.

Night-Time Vision Considerations

Some cameras have special coatings to work with infrared light to provide night vision. Lower priced units provide a compromise; the daytime color quality is impacted by special infrared sensitive coatings. Higher end cameras have special iris compensations for infrared to improve color accuracy. With the rapidly improving chipset technology, we increasingly see the usage of DSP (Digital signal processing) chips to improve picture detail and color detail when lighting is less than optimal.

There are cameras with "starlight" video sensors. Some in the industry suggest that these cameras can be used outdoors to provide good camera signals literally using only starlight. We believe this is a possibility of under-specifying the equipment. Experts we speak with suggest that those cameras can be used in warehouses with some ambient lighting. However, relying on starlight for outdoor use may be problematic on a foggy night with no moonlight available. Our view is that it is better to choose a system that will always be appropriate versus a system that will work some of the time.

Bullet vs. Dome

Another consideration is aesthetics. For example, does the customer prefer a relatively unobtrusive dome style camera or a more visible bullet style camera. For suveillance and security purposes, a larger camera can have a deterrent effect.

Dome cameras are commonly used indoors but are available weatherproofed and vandal-proofed for outdoor applications. Bullet style cameras are typically (but not always) designed to withstand outdoor usage. In our view, many bullet cameras are also pleasing to look at.

Mounting of video security cameras should also be considered. Some dome cameras come with 3-axis mounts, to expand mounting options from the ceiling to include walls. Similarly, most bullet cameras are designed for either wall mounting or ceiling mounting. Some come with 3-axis mounts for use on walls or ceilings.

Dome Camera with 3-axis mount

Bullet camera with integrated cable bracket.

Bullet camera with managed 3-axis cable mount.

There are many other kinds of camera also. The original box style camera is designed to be placed in a specialized housing. These cameras have user selectable lenses, and are often used in custom installations.

We also offer a variety of small,covert style lenses where it is desirable to make the presence of video surveillance less obtrusive. We remind our customers that they must comply with all local regulations regarding placement of cameras (for example they are typically not allowed in restrooms except in some communities by sink areas and typically are not allowed in dressing rooms).

Weatherproofing Considerations

Some of our cameras are designed to be used outdoors. There is a standardized rating scale for outdoor cameras. While no system for ratings outdoor usage is perfect, this can provide a sense of how well suited a camera is for the intended usage. The IP (ingress protection) rating code has two numbers; the first measures protection from solid objects (including dust); the second is a measurement of moisture (water) protection. A reading of 54 or better is considered protection against the elements. We prefer to specify cameras rated at IP 65 or higher for most outdoor applications.

Conclusion

This concludes our overview of camera selections for a digital video surveillance system.We look forward to working with you to integrate a system that meets your needs.