Night Vision Security Cameras – What you need to know
Humans have several great attributes, but seeing in the dark is not one of them. Human vision is limited to a small portion of the electromagnetic spectrum called visible light. It is possible for humans to see beyond this range by making use of equipment which allows us to capture non-visible sources of electromagnetic radiation known as infrared light.
Many CCTV cameras now have the ability to project infrared light using an array of LED illuminators. When this capability is combined with CCD sensors capable of recording the infrared light spectrum, you achieve what is reffered to as night vision.
CCTV security cameras with night vision capabilities allow you to see in total darkness. Many night vision cameras are capable of producing detailed video regardless of lighting conditions. When required, night vision security cameras automatically switch to infrared illumination mode without the need of human intervention.
There are four important things to keep in mind when dealing with night vision security cameras. Distance, resolution, light pollution and sensor type.
Many cameras tout their ability to project infrared light at great distances. Before spending money on a camera that boast such feats, keep in mind that even if a camera can illuminate an object that is far away, chances are you are not going to be able to make out what that object is (unless you are using a camera with a zoom function). It is better to spend your money on a higher resolution camera with a lower infrared capability.
A vehicle will need to be within 50 feet of a night vision camera in order to properly identify the make and model (forget about color with an infrared security camera, the car will always be a shade of green). A person will need to be within 25 feet of the security camera to make a proper ID.
Most security cameras with IR illumination will have a reach of at least 25 feet - therefore the focus should be on bumping up the image detail (or resolution) in order to have a better chance of identifying the subject. Remember that the resolution of the camera must be matched by a recording device that has the capability of recording it. If your camera has 480 lines of resolution, and your Digital Video Recorder can only record 320 lines of resolution, you are loosing the benefit of the higher resolution.
The other issue is light pollution. Many outdoor areas are lit at night. Sometimes by pretty strong light sources. Be very careful not to place your night vision security camera near such light sources, as it will interfere with the sensors and could produce unwanted artifacts in the recorded video.
If you plan to use your night vision security camera in an unlit area, keep in mind that the infrared illuminators do produce a faint reddish glow which can be easily detected at short distances. They may not be the best solution for covert surveillance.
Night vision is a necessary feature for any outdoor CCTV application. When choosing your camera, make sure that it features built in infrared illuminators and a CCD sensor. Cameras equipped with CMOS sensors do not perform as well in the dark, therefore I would recommend that you steer clear of them for outdoor applications. Also look for a camera with an IP55 designation which indicates that the camera is well suited to be used in humid and dusty conditions.
Andy J Thompson is a residential CCTV security camera specialist. For additional tips and informaiton you can read his blog at www.securitycameratutor.com/
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Military Snipers Vs. Police Snipers
A "sniper" is someone who strikes at a target from an undisclosed location. A sniper rifle, therefore, would be any rifle a sniper uses. But commonly, a "sniper rifle" is the name given to any rifle with inherent accuracy, and modifications made to wring the most accuracy out of it. Most common sniper rifles are built from a Remington 700 bolt action rifle. That gun is readily available at most gun shops as an well made and accurate hunting rifle.
Modifications may include a cryo-stress relieved heavy barrel, a composite dimensionally stable stock with aluminum bedding blocks to "free float" the barrel (the barrel is not touched by the stock, so that there is no stress placed on it, and each shot is allowed to harmonically resonate without interference), and a good quality scope.
Each rifle is an individual, but I have seen some capable of shooting into a 1/4" at 100 yards if the operator can do his part. Last I checked,our military generally does not use night vision scopes. Rather, they use night vision headgear through which they look when operating at night. The only purpose for which non-combatants or police would need such equipment would be if they had a serious coyote or other nocturnal predator problem (the distances you cite will be discussed presently, but they are fairly unrealistic).
Scopes don't make rifles accurate. They don't help you shoot better. They help you see better and seeing can be an aid to shooting. But people who don't know how to shoot won't be helped much by any scope, regardless of the cost of it. Some years ago the military was experimenting with propriety technology in regard to a sighting system, but to the best of my knowledge, the project has been abandoned. The cost was very prohibitive, and somewhere along the line someone figured out that seeing better does not equal shooting better.
Although the military has experimented with other cartridges, you will still find the .308 (7.62mm), in use since Korea, to be the most common "sniper" cartridge. It is a good cartridge, but it has more to do with the fact that we have guns chambered in it, and has more data on the effects of wind and drops that for any other cartridge. The army sniper school requires shots to 800 meters with this rifle. The U.S.M.C. sniper school requires shots to 1000 meters.
Those are extraordinarily long shots. If the average rifle can shoot into 1/2" MOA (= 1/2" at 100 yards), that means that it can (all this is predicated on the operator doing his part perfectly, and taking out variables such as wind, etc.) shoot into 100 at 200 yards, 400 at 800 yards, 500 at 1000 yards. Beyond that distance, drop and velocity become such a factor as to make the round fairly ineffective. The "2 mile" shots are typically done with .50 BMG sniper rifles. These huge cartridges and projectiles are not anti-personnel rounds they are used to take out equipment (communications, truck engines, etc.)
The mission of the military sniper is different from that of the police sniper. The military sniper often looks for targets of opportunity; the police sniper a specific target. The military sniper tries to take his shot from as far away as he can (once he gives away his presence by the shot, the enemy will be looking for him); the police sniper tries to get as close as he can; the military sniper operates in less than ideal conditions; the police sniper usually has a matte to lay on, a flat surface to shoot from, etc. The military sniper is at the mercy of his environment; the police sniper is in control of his environment. A miss by a military sniper usually causes no immediate harm; a miss by a police sniper means likely that a hostage will die.
Because of their different operational situations, the military sniper's equipment will trade some accuracy for ruggedness and dependability; because the police sniper shoots "on his terms" his equipment can be the most accurate available, and ruggedness is not an issue (e.g. until very recently, U.S.M.C. snipers had fixed power scopes, because variable power was just too fragile for the field).
To get specifically, unless you are talking about 50 gallon "can," you're not going to hit them from 2 miles away. If that's what you want to do, you'll need a rifle chambered in .50 BMG. If you want to do it in the dark, you'll have to get night vision equipment. Obsolete Soviet stuff is readily available, but modern manufacture is also, if you're willing to pay for it.
This is all about snipers in the military and police snipers and how they are different from each other.
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