What is a Multiplexer?
Put simply, a multiplexer allows several camera signals to be recorded onto one videotape. To do this it
synchronizes the camera signals (lines them up in time) and marks each one with a code, allowing every camera to be replayed independently from tape, regardless of how many cameras are recorded on that tape. In addition, each image is stamped with a time and date caption.
Many multiplexers also provide the ability to view several cameras simultaneously on one or more monitors. This is useful when there is a large number of cameras on
Simplex vs. Duplex
In order to select the right multiplexer, it is important to understand the difference between simplex and duplex operation. These terms refer to how the multiplexer functions during recording and playback. A simplex multiplexer permits recording or playback. Therefore the system is not recording when tapes are being reviewed. Duplex multiplexers can multitask to provide simultaneous recording and playback. Duplex operation therefore ensures that no video data will be missed when recorded material is being reviewed.
Should I use B&W or Color?
Here's a couple of facts that you should know before making this decision. B&W cameras on the whole have a better resolution and have better low light capabilities over color cameras. B&W cameras are also infrared sensitive and can be used even at very low light levels.
With that and the fact that B&W cameras and monitors are cheaper than their color counterparts, you may wonder why we stock color models. Well color monitor have a much clearer picture in the day time and can be crucial for identifying criminals and that is why we highly recommend that you have at least one color camera in your package. That should be placed over your front entrance for prosecution or for a full color report for the Police of the offenders clothing, hair etc.
What are Switchers, Quads, & Multiplexers and which is the best for me?
If you decide to use multiple cameras, which most of you should and will, you will then have to decide on which system you should use to tie in all you cameras to your recorder and/ or monitor. The choice is between Switchers, Quads or Multiplexers. This next section should help you understand the differences between these three.
Switchers are the cheapest solution that start at $125. With this you can ether flick through your cameras yourself manually using a switch or you could set the switcher to automatically cycle through your camera views it self.
Quads are the next expensive solution. Starting at around $165 quads offer some comprehensive features. This solution will allow you to simultaneously record & monitor four cameras at the same time. Like the switchers, Quad also allows you to manually or automatically select which camera view you wish to view full screen. This can only be done with live pictures and not pre-recorded, some Quad manufactures have now found a solution to this using digital images although as the technology stands at present we feel the picture is too pixelated and would not recommend it.
Multiplexers start at around $469. With this system you have the compactly to simultaneously record all cameras and in full screen view.
What is the Difference Between C & CS Mount lenses?
The physical difference is that the back of a CS mount lens is 5mm closer to the chip than a C mount lens. You can always use a C mount lens on a CS mount camera by using a 5mm spacer ring (many cameras now have C/CS selectable adjustment screws or rings).
You can never use a CS mount lens on an older style C mount camera. Cost wise the CS mount lens is much less expensive since it uses fewer glass elements. Quality of image is the same. C mounts are becoming less and less popular and
are generally only used on the more telephoto focal lengths such as 25, 50 and 75mm, and bigger zooms.
What is a Vari Focal Lens?
A lens that can zoom in and out manually.
What does BNC Stand for?
BNC literally stands for Bayonet Neill-Concelman. The connector was named after its bayonet mount locking mechanism and its two inventors, Paul Neill of Bell Labs (inventor of the N connector) and Amphenol engineer Carl Concelman (inventor of the C connector),
What is Focal length?
While a photographic lens comprises multiple lens elements, it can be regarded as a single convex element. The focal length is defined as a distance from the center of such a convex element (principle point) to the focal point (image plane) and it is one of the most decisive factors that determines the characteristics of a lens.
* The focal length of a photographic lens is established with the subject positioned at the infinity point.
Angle of View (Telephoto & Wide-angle Lens)
The area size captured by a photographic lens can be expressed as a diagonal angular field called Angle of View. Generally speaking, a focal length range that provides a similar perspective to the human eye is considered to be somewhere between 40-60mm. With this established as a standard focal length, those with shorter focal lengths are called "wide-angle" and those with longer focal lengths are called "telephoto". The shorter the focal length becomes, the wider the angle of view (wide-angle), while the longer it becomes, the narrower the angle of view (telephoto).
* The relationship between focal length and angle of view is generally consistent regardless of the lens focal length. However, there are cases where different angles of view are observed depending on the difference in the focusing system of a lens and shooting distance.
Perspective (Sense of distance)
A photographic lens provides a visual effect, making closely located subjects larger while remotely located subjects smaller. As the focal length becomes shorter in a
wide-angle lens, this perspective difference expands making closely located subjects even bigger and remotely located ones even smaller (exaggerated perspective).
In contrast, in a telephoto lens, as focal lengths become longer, less difference is observed between close and distant subjects, making it appear as if they are closer regardless of the distance between
them (compressed perspective).
Depth of Field
When focused on a subject, there are areas in front of and behind the main subject where details are sharp. This area is referred to as depth of field. When the sharp image area is narrow, it is expressed as "shallow depth of field". When it is wide, it is expressed as "deep depth of field". The depth of field becomes shallower as the lens aperture goes toward a full open position (or the faster the lens' maximum aperture becomes). It becomes deeper when the aperture gets closer to the fully stopped down position (or the slower the lens' maximum aperture becomes). Also, a
wide-angle lens delivers deeper depth of field compared with a telephoto lens.
What's the Difference Between Spectra III and Spectra III SE Domes?
Pelco Spectra III SE Series Dome drives feature LowLight Technology. The color/black-white model features a 23X zoom lens, built-in motion detection and 80X wide dynamic range imager. Two standard cameras, available in color or monochrome, feature 22X zoom lens and Exview HAD imagers for increased sensitivity.
The Spectra III Series Dome System is a cost-effective alternative to Pelco’s popular Spectra III SE Series Dome System. The Spectra III features multiple back box configurations and a high-resolution LowLight Color dome drive with a 16X zoom lens.