CCTV Lenses
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1 Monster Zoom CCTV LensesOur Monster Zoom Lenses start at 10mm and goto 2000mm, these huge lenses will put a 6' man at 25% of your screen at 5 miles. Monster Zoom lenses are generaly used for Military applications or exotic CCTV requirements
2 Motorized CCTV Zoom LensesMotorized CCTV Zoom Lenses are used for extreme distances and allow you to control them remotely to zoom in or out, and range from a few hundred dollars to over $50,000 for top quality 2000mm zoom lenses.
3 Advanced Professional CCTV LensesAdvanced Professional CCTV Lenses are manufactured from the most advanced Japanese technology, their refraction allows the most ambient light to shine on the CCD sensor. Advanced Professional CCTV Lenses are aspherical lens's. Aspherical refers to non-spherical elements in lenses designed to compensate for distortion by having different curves on individual elements which allow for more compact lenses that are lighter and better than non-sperical lenses.
4 Auto Iris, Fixed Focal CCTV LensesAuto Iris, Fixed Focal CCTV Lenses are used when you know the exact FOV - Field of View and that the FOV will never change and where the light levels change all the time such as an outdoor CCTV surveillance system.
5 Auto Iris, Vari-Focal CCTV LensesAuto Iris, Vari-Focal CCTV Lenses are used when you need to adjust the FOV - Field of View to zoom in on a object or location and focus in for a clear image. The Auto Iris adjusts to the fluctuation light and cost only a few dollars more than Fixed focal lens. Auto Iris, Vari-Focal CCTV Lenses will let you change the focal length to suit the application if you should ever have to move or change the object or location you need to view. There is one dial for zooming and one dial for focusing.
6 Vari-Focal, Manual Iris CCTV LensesVari-Focal, Manual Iris CCTV Lenses are used when the budget is really pushing it and you have to make ever dollar count but still have some functionality to it. Vari-Focal, Manual Iris CCTV Lenses can be used anywhere the lighting dows not change or you wil be continuosly changing the Iris to adjustto the light levels. Vari-Focal, Manual Iris CCTV Lenses must be changed manually.
7 Fixed Focal, Manual Iris CCTV LensesFixed Focal, Manual Iris CCTV Lenses are lens with a set focal length such as 4 or 6mm which are the most common, and will require you to adjust the Iris manually. Fixed Focal, Manual Iris CCTV Lenses are used when the lighting and scene never changes.
8 Fixed Iris, Fixed Focal CCTV LensesFixed Iris, Fixed Focal CCTV Lenses like the Manual Iris lenses are used for very specific areas, where the FOV - Field of View never changes and where the light levels do not change. When using Fixed Iris, Fixed Focal CCTV Lenses the lighting cannot change or your image on your montor will be either way over exposed or underexposed producing unseable images.
9 Telescopic CCTV LensesTelescopic CCTV Lenses are manually controlled and mostly used for observation at a great distance but allow you to attach a Professional Box CCTV camera to it then monitor it on a screen or record it to a DVR - Digital Video Recorder. Telescopic CCTV Lenses mount to a tripod (sold separately) so you’re not constantly trying to hold it steady like binoculars.
10 CCTV Lens AccessoriesCCTV Lens Accessories ranging from " C " to " CS " CCTV lens adapters to tripods and mounts for telescopic lenses.


Order your security camera lenses from WECU Surveillance.com! we have all the security camera Lenses & Information you will ever need!!

  • Click here for a downloadable Lens Calculator, This is a .NET application requires the host support Microsoft's .NET Framework. If it's not already installed, Click here to download the .NET framework from Microsoft, please save to your PC before running the program.
  • Click here for the Lens Field of View Chart for 1/3" CCD cameras


Please take note when purchasing lenses to make sure the lens matches the camera

People often ask how far can a CCTV lens see... Well a 2.8mm lens can see to infinity. The information you need to supply is what you need to see at a specific distance for example I need to recognize a man at 250ft, with this being said a 86mm - 122mm lens would work just fine. It all depends what you want to see at what distance.

There are many factors involved in choosing a suitable lens, as the lens size increases the left to right field-of-view narrows and the distance increases.
  • A variable focus 3.8mm ~ 9.5mm lens is ideal for monitoring hallways, doorways, and average size rooms
  • A 5.0mm ~ 50mm lens has the ability to be used for monitoring hallways and doorways and can be easily adjusted to monitor long driveways or areas several hundred feet away.
Beware of many online lens calculators which produce inaccurate angle measures for these focal lengths. Also, most 1/4" CCD cameras produce a significantly narrower field of view with the same focal length lens.

Due to the physical nature of lens optics, the numbers listed below should be considered accurate to within ± 3° and therefore a few feet / meters as well. They are intended as approximate guidelines to help select the appropriate lens, while each camera in fact has its own unique field of view with each specific lens. In addition, C- and CS-mount lenses typically deliver a slightly narrower field of view than our comparable board lenses.

Lenses wider than roughly 5mm produce "artificially" wider fields of view than more telephoto lenses. In order to do so, the video image is slightly curved at the edges of the screen. While this artificial distortion is nominal for focal lengths between 4.3 and 3.6mm, curvature increases with wider angle lenses.

Each size lens is available with a manual or auto-iris lens.
  • The manual-iris lens is more affordable but should only be used in indoor applications where the light source remains constant
  • The auto-iris lens can be used for indoor areas with varying light conditions as well as outdoor installations.
HELP ON HOW TO SELECT LENSES:
  • SELECT SIZE: if your camera has 1/3" imager size you can go for 1/3" or 1/2" lenses. If your camera has 1/2" imager size you can use 1/2" lenses.
  • SELECT MOUNT TYPE: in 90% of cases it will be CS, check your camera's manual
  • SELECT FOCAL LENGTH: If camera is strictly indoors and light never changes go for manual iris lenses
  • SELECT TYPE OF IRIS: if camera is for outdoors or light changes go for DC iris lenses (camera must support DC iris lenses) or video auto iris lenses
  • Varifocal lens will give you flexibility in adjustable field of view.
Quick Q & A
  • Q. What is the difference between the Standard lens and the Day / night lens?
  • A. It's a little complicated but basically the day/night lens accounts for the IR cut filter flipping up and down, a regular lens does not, so if you put a regular lens on a Day / Night camera, when it changes to black and white it gets blurry, they call it focus shift.


  • Q. What is LUX?
  • A. During the day the amount of illumination reaching a scene depends on the time of day and atmospheric conditions. Direct sunlight produces the highest-contrast scene, allowing maximum identification of objects. On a cloudy or overcast day, less light is received by the objects in the scene, resulting in less contrast.

    To produce an optimum camera picture under the wide variation in light level (such as occurs when the sun is obscured by clouds), an automatic-iris camera system is required. Typically, scene illumination measured in foot-candles (ftcd) can vary over a range of 10,000 to 1 (or more), which exceeds the operating range of most cameras for producing good quality video images.


The chart below summarizes the light levels occurring under daylight and these low light level conditions. The equivalent metric measure of light level (lux) compared with the English (ftcd) is given.

LUX Rating Chart

  • Q. What does Manual Iris Lens mean?
  • A. Manual iris lenses provide an effective solution for applications where the scene and lighting requirements are relatively stable, especially when used with security cameras that are equipped with electronic shutters.


  • Q. What does Auto-Iris Lens mean?
  • A. Auto iris lenses produce consistent video signals in scenes with varying light levels, thus enabling reliable surveillance in areas that would otherwise be compromised.


  • Q. Should I use Manual or Auto Iris Lenses?
  • A. You can save money and use Manual Iris Lens only when scene illumination never changes.
    Example: Illuminated store or office. If the light changes a lot it is recommended using Auto-Iris.
  • Q. What's Varifocal Lens?
  • A. The Varifocal lenses are ideal in situations where the security camera surveys a distant point. One can adjust the zoom and focus of these lenses either manually or automatic. Often it is not possible to determine the focal length of a lens required to meet a particular application or install, it is possible the angle or FOV - Field of view cannot be achieved by a standard lens.

    So manual / remotely zoomed lenses have been developed to meet these not so specific applications. These are known as " Vari-Focal " lenses or Variable focal length lenses and are available in a many different focal length configurations, but not too many to make it confusing. The exact angle of view can be set at the installation point but it is important to ensure that the FOV - Filed of View required has been addressed prior to installation and is available within the lens's range, for example 3-12mm or 9-22mm etc...


  • Q. What Focal Length will I need?
  • A. The smaller the focal length number = the wider the field of view.
    • If you have a security camera in the office or warehouse and you want to see as much as you can, you should go for 2.8 or 4 mm lens this makes a wide, somewhat distant view.
    • If you want to observe a limited area, like an entrance you should go for 8 or 12 mm or higher this makes a narrow view and objects are closer.


  • Give us a quick call at 1.877.843.3921 and we can help you determine what security camera lens will best suit your location.

Use Varifocal lenses for flexibility in choosing the best field of view.

  • Q. What is the (FOV) Field of View and how much will the security camera see?
  • A. The field of view (FOV) is based on the camera & lens. WECU Surveillance has many different types of Lenses to suite any and all of your CCTV security camera needs. Wide angle lenses are suitable for most applications due to their ability to view a large area. A 4mm wide angle lens will be able to view an area 23.5' wide x 17.5' high at 20' away and a man at 5'2" tall will be 30% of your screen height, with a 1/3" CCD chip CCTV camera.

    As an example, a 15' x 15' room is shown in the diagram below. Observe that the 4mm lens (green arrows) allows better wide angle viewing coverage than the 12mm lens (red arrows). In applications where a closer view is needed (such as above a cash register or over a greater distance), an 8 or 12mm may be desired. The same camera (above) at 21’ away with a 8mm lens will have a 13' wide x 10' high FOV.

    At 20' with a 12mm lens, the FOV will be 8' wide x 6' high and a man 5'2" tall will be 86% of your screen height with a 1/3" CCD Chip CCTV camera. Increasing the focal length of the lens decreases the perceived distance to the viewing area. See the FOV diagram below for approximate views with different focal length lenses.


(FOV) Field of View Chart

  • Q. What is the Depth of Field?
  • A. The depth of field refers to the area within the field of view which is in focus. A large depth of field means that a large percentage of the field of view is in focus, from objects close to the lens often to infinity. A shallow depth of field has only a small section of the field of view in focus.

    The depth of field is influenced by several factors. A wide angle lens generally has a larger depth of field than a telephoto lens, and a higher F stop setting typically has a larger depth of field than a lower setting. With auto iris lenses, the automatic adjustment of the aperture also means constant variation of depth of field. The small depth of field is most apparent at night when the lens is fully open and the depth of field is at its minimum. Objects that were in focus during the day may become out of focus at night.


  • To break it down a little more... Depth of Field describes the area in front and behind the target which appears in focus and is affected and controlled by the following:

    Focal length of the lens: The shorter the focal length the greater the depth of field, for example a 2.8mm wide angle lens has a greater depth of field than a 50mm or telephoto lens (200mm or greater)

    Distance between camera and target: The farther the distance between the camera and the target, the greater the depth of field. As you get closer to your subject, the depth of field will narrow, this is why extremely close shot will usually have a blurred background and parts of the target are out of focus. This problem can be helped by using a shorter focal length lens.

    Lens Aperture: The lens contains what is called an aperture and is measured in f-stops. The aperture controls the amount of light passing through the lens to the film plane inside your camera. This is found on the ring nearest your camera, the numbers should be on the ring. Depending on the quality of the lens, you'll normally see numbers such as 2.8, 4, 5.6, etc... These numbers denote the size of the opening inside the lens.

    The smaller the number, the larger the opening inside your lens, for example at an F stop of 2.8 your lens aperture is wide open, at f stop of 11 or 16, your lens is "stopped down" which means the aperture is almost closed.

    Depth of field can be controlled by the aperture of your lens, the larger the aperture opening (2.8) the narrower the depth of field, the smaller the opening (16) the greater the depth of field; The lens works exactly as your eye works, in bright light, your iris closes which gives you greater depth of field and things appear much sharper.


  • Q. What is F STOP?
  • A. A lens usually has two measurements of F stop or aperture, the maximum aperture (minimum F stop) when the lens is fully open, and the minimum aperture (maximum F stop) just before the lens completely closes. The F stop has a number of effects upon the final image. A low minimum F stop will mean the lens can pass more light in dark conditions, allowing the camera to produce a better image at night.

    A maximum F stop may be necessary where there is a very high level of light or reflection, as this will prevent the camera from "whiting out", and help maintain a constant video level. All auto iris lenses are supplied with Neutral Density spot filters to increase the maximum F stop. The F stop also directly affects the depth of field.


  • Q. What is a Aspherical Lens?
  • A. Most commonly available lenses are made from glass or higly quality clear plastic which has been ground to a very precise spherical shape in order to achieve its optical properties of being able to refract and focus light. Using sperical shapes gives very good results when the light passes at or near to the center of the lens, but as light passes though the points furhter from the center, small refraction errors are introduced which get worse the farther from the lens center that the light passes. This effectively limits the maximum light gathering area or aperture-ratio (f-number) that a sperical lens may have.


  • Asperical lenses are ground not into spheres but other carefully calulated, complicated shapes, which reduce errors in light refraction. Hence an aspherically ground lens can have a much larger effective light gathering area i.e. its aperture-ratio (f-number) can be much smaller. The maximum aperture of a standard sperical lens is typically F1.4 whereas that of and aspherical lens is f1.0 or f0.8.

    Asperical lenses are more expensive than standard lenses due to the more complicated and time-consuming grinding techniques that are necessary in their production. However their use can often be justified because it can preclude the need for a more sensitive, and hence expensive, camera or increasing the sight illumination.


  • Q. What are Pin Hole Lenses?
  • A. These are primarily used for covert surveillance. They have very small front " object " lenses which mean that they can be put behind very small holes and be virtually undectable. Straight and right-angled models are available to facilitate the mounting of the camera and to reduce the depth required behind the conceiling surface. Due to the small objective lens, pin-hole lenses cannot gather as much light as conventional lenses and so their use dictates that the scene illumination is better than would otherwise be required.


  • Typically the maximum apertures on a pin-hole lens is F2.5 to F3.5 which is approximately 2 to 3 stops less than standard lenses. Between 4 and 8 times the normally quoted minimum scene illumination is required for the camera to produce a useable picture.

  • Q. How do I correctly Back - Focus my camera?
  • A. You should be doing your master focusing prior to installation. Correct camera / lens focus is one of the truly last major problems left in the field of CCTV camera setup. To accomplish this, you need to back-focus your camera and lens.... This is a form of setting the camera to a generic focal point and then doing the fine adjustments in the field. Listed below, are the procedures for setting the back-focus for various types of operations:


  • Zoom Lenses

    To obtain proper back focus (tracking) of a camera with a zoom lens, the following steps must be followed. If these steps are shortcut or avoided, proper tracking of the lens will never be possible.

  1. Set the lens to full wide angle (widest scene possible)
  2. Set the physical lens focus to full infinity
  3. Insert a gel, welding lens, or other type of filter in front of the lens to force the iris into the full open position. If you contact a manufacturer, they will tell you to use an "ND" (neutral density) filter. These filters are very expensive however. To combat cost and potential loss (dropping of very expensive filters) I recommend welding glass filters (about $5.50 each). I also recommend that you purchase four different densities to combat the various lighting conditions that you may be working under (#1, #3, #5, #8). A #1 filter is very light and is like a pair of sunglasses. A #8 filter is extremely dark and is good for very bright conditions (full sunlight)
    • 3a. Do not use such a dark filter that a usable picture is not obtainable
    • 3b. Use a glass filter versus a plastic filter, if possible, to insure purity of view
    • 3c. It is essential that the iris is opened to full position
  4. Using a screwdriver of appropriate size, adjust the imager positioning screw of the camera for best picture while viewing an object 75 feet away for one inch cameras and 50 feet away for two thirds inch and smaller cameras.
    • 4a. The imager position screw may be called several things on different types of cameras: Vidicon positioner, imager positioner, tube positioner, etc...
    • 4b. The imager positioning adjustment on most quality cameras can be reached from the outside of the camera..
  5. Zoom the lens in for the closest view of the object 50 to 75 feet away
  6. Adjust the manual focus of the lens for best picture
  7. Zoom the lens out for widest picture. The picture should remain in focus. If it does, the camera is adjusted properly. If it does not, the camera is still out of back focus and steps #1 through 6 should be repeated
    • 7a. If a 2X Tele-converter lens is used in conjunction with any zoom lens, back focus will not be possible. Adjust the Imager position for best picture at either near or far view and leave it
  8. Remove the filters and reinstall the camera to service
Standard Fixed Focal Length Lens

  1. Set the physical focus of the lens for full infinity
  2. Insert a gel or filter to cause iris to open completely. (See Paragraph #3, #3a, #3b, #3c under Zoom Lenses above)
  3. Aiming the camera at an object that is the same distance as the primary scene to be viewed, adjust the Imager position for the best picture
  4. Remove the filters and reinstall the camera with the lens in position to provide best possible manual focus
CS Lens & Camera

Back focus, or the initial setup of the CS style camera and lens, is slightly different as well.

Since the focus optics of the fixed focal length CS lens and the imager positioning mounts of the CS style cameras have been removed, a slightly different approach to back-focus is taken. The end result, however, is the same.


  1. Locate and loosen the CS lens collar lock(s)
  2. Insert a gel or filter to open the iris of the lens completely. (See Paragraph #3, #3a, #3b, #3c under Zoom Lenses above)
  3. Aim the camera at an object that is the same distance as the primary scene to be viewed
  4. Adjust the CS collar of the lens for best picture
  5. Re-tighten the CS collar lock(s) and remove the filter
Camera back focus adjustment ensures that a camera's image remains in focus during changing lighting conditions. This is a common problem in CCTV installations where one sees a sharp image during daylight but a blur at night. During bright sunlight, the lens iris is closed and the depth of field very wide. When the light level drops, the Iris opens and the depth of field decreases. To reach the optimum focus, the camera needs to be back focused with the lens’s iris fully opened. Proper back-focus adjustment also holds true for zoom lenses which need to be properly adjusted to hold focus through the zoom range.

Camera back focus adjustment ensures that a camera's image remains in focus during changing lighting conditions. This is a common problem in CCTV installations where one sees a sharp image during daylight but a blur at night. During bright sunlight, the lens iris is closed and the depth of field very wide. When the light level drops, the Iris opens and the depth of field decreases. To reach the optimum focus, the camera needs to be back focused with the lens’s iris fully opened. Proper back-focus adjustment also holds true for zoom lenses which need to be properly adjusted to hold focus through the zoom range

Choosing the right Lens

Once you have selected a camera, the next step is to select the appropriate lenses and any other relevant components necessary in the system.
There are two main lens mount standards called C-mount and CS-mount. They both have a one-inch thread and they look the same. What differs is the distance from the lenses to the sensor when fitted on the camera:
  • CS-mount. The distance between the sensor and the lens should be 12.5 mm
  • C-mount. The distance between the sensor and the lens should be 17.5 mm. A 5 mm spacer (C/CS adapter ring) can be used to convert a C-mount lens to a CS-mount lens
The initial standard was C-mount, while CS-mount is an update to this, allowing for reduced manufacturing cost and sensor size. Today, almost all cameras and lenses sold are equipped with a CS-mount. It is possible to mount an old C-mount lens to a camera with CS-mount by using a C/CS adapter ring. If it is impossible to focus a camera, you probably have the wrong type of lens.

C & CS Lens mount

Sensor size Image sensors are available in different sizes, such as 2/3", 1/2", 1/3" and 1/4", and lenses are manufactured to match these sizes. It is important to select a lens suitable for the camera. A lens made for a 1/2" sensor will work with 1/2", 1/3" and 1/4" sensors, but not with a 2/3" sensor.

Sensor Size

If a lens is made for a smaller sensor than the one actually fitted inside the camera, the image will get black corners. If a lens is made for a larger sensor than the one actually fitted inside the camera, the angle of view will be smaller than the default angle of that lens – part of the information being "lost" outside of the chip (see illustration below).

Chip Size

Image sensors: CCD vs. CMOS

The image sensor of the camera is responsible for transforming light into electrical signals. When building a camera, there are two possible technologies for the camera's image sensor:

  • CCD (Charged Coupled Device)
  • CMOS (Complementary Metal Oxide Semiconductor)
1/3-inch CCD sensor

1/3-inch CCD sensor
1/4-inch CMOS sensor
1/4-inch CMOS sensor

CCD and CMOS are the critical components that act as a camera's "digital film." CCD sensors are produced using a technology developed specifically for the camera industry, while CMOS sensors are based on standard technology already extensively used in memory chips like inside PCs, for example. Today's high quality cameras use mostly CCD sensors. Although recent advances in CMOS sensors are closing the gap, they are still not suitable for cameras where the highest possible image quality is required. However, CMOS sensors may be ideal for entry-level cameras where size and price are important factors.

Image sensor placement

CCD technology

CCD sensors have been used in cameras for more than 20 years and present many advantageous qualities; among them, better light sensitivity than CMOS sensors. This higher light sensitivity translates into better images in low light conditions. CCD sensors are, however, more expensive as they are made in a non-standard process and more complex to incorporate into a camera. In addition, when there is a very bright object in the scene (such as a lamp or direct sunlight), the CCD may bleed, causing vertical stripes below and above the object. This phenomenon is called a smear.

CMOS technology

Recent advances in CMOS sensors bring them closer to their CCD counterparts in terms of image quality, but CMOS sensors remain unsuitable for cameras where the highest possible image quality is required. CMOS sensors provide a lower total cost for the cameras since they contain all the logics needed to build cameras around them. They make it possible to produce smaller-sized cameras. Large-sized sensors are available, providing megapixel resolution to a variety of network cameras. A current limitation with CMOS sensors is their lower light sensitivity. While this drawback is not an issue in bright environments, in low light conditions it becomes apparent. The result is either a very dark or a very noisy image.


Lens distance examples:

Distance from Camera to vehicle is 40 feet

3.5mm - Picture area
54.5' w x 41' h
3.5mm - Picture Area 49' w x 35' h
6mm - Picture area
31' w x 23' h
6mm - Picture area 29' w x 21' h
8mm – Picture area 24' w X 18' h
8mm – Picture area 22' w X 16' h
15mm – Picture area
13' w X 10' h
15mm – Picture area 12' w X 9' h
55mm – Picture area
3.5' w x 2.5' h
55mm – Picture area 3.25' w x 2.50' h

General Security Camera Lens Information:

The lens of a security camera is like the cornea of your eye. Without it you cannot see, and neither can the security camera. There are many different types of security camera lenses in the security camera market.
  • The first division between lenses are the wide angle and the zoom lens.
  • The next division is between the auto iris, manual iris, or no iris at all.
  • These choices and others depend on the intended use of your security camera system. Correct security camera lens choice should be determined by your application and your requirements.
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