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Varifocal vs Fixed Lens Security Cameras

What's the difference and when would I need varifocal lenses?

Part 1 - What's the difference?

A fixed lens doesn’t let you adjust the focal length, angle of view, and level of zoom. Almost all fixed lens cameras have a wide angle.

With a varifocal camera, you can adjust these things. Let's look at some examples of what this means:

This an image from a fixed lens 4MP camera (The Wasp Pro 4.0), which is fixed at 4mm with someone standing 10 feet away


This is an image from a 4MP bullet camera at 12mm (The Hornet Pro 4.0, which is adjustable from 2.8 to 12 mm)


By increasing the focal length, you get a much better image of the man/license plate. At 10 feet, this doesn't matter very, much but at larger distances (which we will show in a second) this can mean the difference between identifying a suspect and not getting a clear enough picture of their face.


There is a drawback to increasing the focal length, however.

By increasing the focal length (the mm setting) and magnifying an area, you reduce your viewing angle, as superimposing the 12mm image on top of the 4mm one easily shows. You get a lot more detail for one area at the cost of losing a wide angle view.


Not just two settings

A varifocal camera allows you to adjust between its top and bottom limits on its view angle. This means that you have the ability to manually set both the view angle and level of zoom. Have a scenario where you need to zoom in on a gate or other access point? Use the 12mm setting (12 degrees and about 4x zoom). Need a wide angle view? Go with 2.8 mm (109 degrees). Need something in between? Try 6mm (~45 degrees) or 9mm (~30 degrees).

How to Adjust the Lens

Each camera will be a little different, but most adjustable lens cameras are adjusted manually at the camera. Continuing with using the Hornet as an example, you would take off the outer case to reveal two knobs. Like so:

Looking to change the viewing angle on the fly when responding to active security threats?

We also have PTZ cameras which allow you to pan, tilt, and zoom with a joystick and motorized varifocal cameras, like the Warden 4.0, that allow you to adjust the level of zoom remotely.

Cameras with mechanical optical zooms or PTZ functions can be adjusted via a joystick or the on-screen controls:

Part 2 - When Would I Need a Varifocal Lens?

One camera in a square room - When vari-focal cameras are nice

Because your normal fixed lens is 75 degrees, placing a fixed lens camera in the corner of a square room, will give you a coverage map like this:

This means that you really need two cameras to cover that area. With one 98 degree camera, you could cover the whole space and not have to buy two cameras (The walls are 90 degrees). So, a varifocal camera, set at 98 degrees would be able to see the whole room.

Distance - When vari-focal cameras become necessary

At about 50-100 foot a wide angle lens 1080P camera, will not doing a tremendously good job at identifying faces. (At about 20 foot, a standard definition camera will also not work identify faces, but if you are willing to pay for a vari-focal standard definition camera you should go HD wide angle - for about the same price as a standard definition vari-focal, you get a higher resolution picture that extends the distance that you can identify faces while not giving up any the wide angle view).

To demonstrate why varifocal cameras are necessary at distance, here's a picture of the same man throwing a rock with the same 1080P fixed lens camera (The Wasp), this time from 50 feet

And now from 100 feet


With greater distances, a wide angle view camera will lack the ability to identify faces. It becomes necessary to use a higher millimeter lens when you are trying to identify a security threat that is further away.

Here's the same two scenarios with the Hornet set at 12mm


Practical Applications: When you should absolutely use a Vari-focal Camera

1. When you only have the budget to have have one camera in a room, only need one, and the room has 90 degree walls.

2. When you are have a gate, door, or other known entrance point but can't mount a camera very close.

3. When it is imperative that you get a close shot to identify a person or vehicle and have a good idea where they are going to be.

4. Anytime you want to identify someone more than 50 ft away.

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  1. The Wasp Pro 2.0 43220 - 1080P 2MP Fixed Lens Mini Bullet Camera



    The Wasp Pro 2.0 43220 - 1080P 2MP Fixed Lens Mini Bullet Camera

    In stock.
    Usually ships the same business day if ordered before 2PM EST.

    $150.00


    Resolution

    1080p HD

    1080P (2MP) @ 30 FPS
    1920 × 1080
    Compression: Not All 1080P Cameras are Created Equal


    Weather

    weatherproof

    Rated IP66 - full protection from dust, rain, and sprinklers. You can even wash them off with a hose.


    Temp

    temperature rating

    Temperature rated from -22°F to 140 °F at below 90% humidity.


    Lens

    fixed lens

    Fixed: 4mm
    75° of coverage


    IR

    infrared

    Infrared night vision up to 100 FT


    Special

    special features

    Vandal Proof Housing

    Digital Zoom Only

    Learn about the 4 types of Zoom



  2. Wasp Pro 4.0 v2



    The Wasp Pro 4.0 v2 43240 - 4MP (2x1080P) Fixed Lens Mini Bullet Camera

    In stock.
    Usually ships the same business day if ordered before 2PM EST.

    $199.00


    Resolution

    4MP UHD Quality

    4MP @ 20 FPS
    2560 x 1440
    Compression: Not All 1080P Cameras are Created Equal


    Weather

    weatherproof

    Rated IP66 - full protection from dust, rain, and sprinklers. You can even wash them off with a hose.


    Temp

    temperature rating

    Temperature rated from -22°F to 140 °F at below 90% humidity.


    Lens

    fixed lens

    Fixed: 4mm
    75° of coverage


    IR

    infrared

    Infrared night vision up to 100 FT
    Good for Low Light: 0.01 Lux Rating


    Special

    special features

    Wide Dynamic Range

    Vandal Proof Housing

    Digital Zoom Only

    Learn about the 4 types of ZoomMicroSD Card Slot



  3. The Hornet Pro 4.0 v2 Motorized 44240 - 4MP (2x1080P) Multi-Purpose Lens Bullet Camera with Motorized Zoom and Focus



    The Hornet Pro 4.0 v2 Motorized 44240 - 4MP (2x1080P) Multi-Purpose Lens Bullet Camera with Motorized Zoom and Focus

    In stock.
    Usually ships the same business day if ordered before 2PM EST.

    $399.00


    Resolution

    4MP UHD Quality

    4MP @ 20 FPS
    2560 x 1440
    Compression: Not All 1080P Cameras are Created Equal


    Weather

    weatherproof

    Rated IP67 - full protection from dust, rain, and sprinklers. You can even wash them off with a hose.


    Temp

    temperature rating

    Temperature rated from -22°F to 140 °F at below 95% humidity.


    Lens

    fixed lens

    Motorized Varifocal: 2.8 - 12mm
    98° - 30.5° of coverage


    IR

    infrared

    Infrared night vision up to 150 FT
    Good for Low Light: 0.01 Lux Rating and Wide Dynamic Range


    Special

    special features

    Motorized Zoom and Focus

    Vandal Proof Housing, Micro-SD Card Slot

    Digital Zoom and Optical Zoom

    Learn about the 4 types of Zoom


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