The Issue with Fisheye Cameras

[Keoni Granger]

The Issue with Fisheye CCTV Cameras​

Fisheye cameras get returned to us more than any other camera by far. Many people believe that the bigger the viewing angle, the better the camera but in this post we'll be explaining why this isn't necessarily true.

We find that customers come to us requesting fisheyes because they've heard that they utilise a 360° field of view and they want to be able to cover every area possible in high detail. However, stretching an image across 360° is extremely detrimental to the quality of the images captured and it proves difficult to identify objects/people of interest within your image.

In the example image below you can see that although the fisheye is covering everything in the workshop, it's actually really difficult to identify anything specific because of how warped the image is. The only thing that would be in detail would perhaps be the top of someone's head as they passed under the camera!

In this scenario I would instead recommend using a couple of 2.8mm/4mm cameras pointed towards areas of interest as this would provide a maximum viewing angle of around 90° and be able to capture number plates and faces in high detail.

If we use a 3MP camera as an example, you can imagine how 3 million pixels used to build up a 90° image would be of much better quality than that where 3 million pixels have also been used to build up an image spanning 360°. CCTV users know that a 3MP camera is high quality so we find that our customers are usually disappointed when their 3MP fisheye doesn't produce the results that they expected. In our post explaining Hikvision focal length differences, image warping and loss of quality is noticeable even in our 2.8mm (90°) example image.

When should I use a Fisheye?

There have been a few applications where we have recommended fisheye cameras to our customers. We find that they tend to be a suitable option when the camera is to be mounted directly above an area of interest such as a factory/work bench/cooking station and needs to monitor the activities.

I hope this quick explanation helps to visualize why we find fisheyes to be disappointing, please let us know if you have any questions!

 

[Magic919]

That’s 180 degrees rather than 360.

 

[Phil]

Conventionally for these it's 360° when ceiling-mounted, and 180° when wall-mounted:
(from 1min 18secs in this video for example)

 

[Magic919]

The angle of view, which is being discussed in this thread is 180 degrees. Mounting on a ceiling provides what they call a 360 degree viewing experience. Two different things.