Buying security cameras can be a daunting task, especially when you’re dealing with all the jargon that comes along with it like – H264, MJPEG, and I.R. megapixels. Then throw into the mix different lens sizes, motion detection, trip wire etc… and you have a recipe for disaster where you may end up buying something you thought would protect your family or valuables, only to have it fail miserably after costing you a small fortune.
So, let’s see if we can arm you with the right information so you can make a choice that will suit your needs.
To begin with, megapixels are just the tip of the iceberg when looking at cameras. How the image is captured and stored is just as vital. For example, you can have a smart phone with a 16 megapixels camera and a SLR photographer’s camera with the same megapixels, yet the two pictures will be very different. This is due to the size of the image sensor lens quality and compression software – that’s why you don’t see press photographers taking pictures with their smart phones (even though that would make life easier).
So, let’s start with compression software, which is how the images are put together and stored. If you could imagine that video images are just a bunch of still pictures put together, how each frame is captured makes a big difference. Some compression software will store every single frame, while others will only store frames that are different from the last stored frame. Without making your head spin too much for your average home and commercial site, the best software to run is H264. This gives you high quality images and it takes up less hard drive space.
As for image sensors, rule of thumb is ‘bigger is better’ for the average user. Anything above 1/3 image sensor and you’re doing well.
Next, let’s discuss lens sizes. In general, the lower the lens size, the wider the field of view. For example, 3.6mm lens will give you a 90 degree field of view and a 12mm lens will give you a 25 degree field of view. Therefore, when you’re looking at covering certain areas of your property you may want to take this in to account
Now we get to motion detection, trip wire or intrusion detection. I’ll try and keep it simple without giving a science lesson. Motion detection will detect any movement made on the screen within a certain size (depending on the sensitivity). Some people will set the cameras to send them notifications when they detect movement. However, unfortunately at night, the infrared light that the cameras put out can give false notifications. For example, when a bug flies past the camera at night, infrared light bounces off the bug and back into the camera and in turn is considered movement by the camera.
As for trip wire or intrusion detection, this is a programmed line that only the camera can see, so this gives you greater control over what areas you want to cover with less false notifications. If a person walks past your property, the cameras won’t detect them but if they step foot over the invisible line that you have drawn in the camera, it will act just like a real trip wire and notify you.
Hope this has been helpful to you.