Camera resolution - Is more always better?

Let's get very slightly technical here, just enough to get an understanding of how pixels on a camera work. Inside every camera is a little light collecting circuit called a CCD. The CCDs job is to collect light and pass it through to the camera for processing into the image you see on your screen. The CCD is covered in little sensors that collect the light - the higher the megapixel, the more sensors on the CCD, the higher the resolution image you will get. So this all seems to point to higher resolution being the better option; not so fast.

CCDs come in a range of sizes; but ultimately on CCTV cameras they are standardised. Which means that whether your CCD has 2 million pixels or 12 million pixels........the space to cram them into is the same. The obvious approach is to make the little sensors smaller so they can all fit, great...done. So now we have 12 million sensors in the same space as 2 million, we of course need to make them smaller to fit. Now we have a problem....light sensors collect light based on their physical size, so a larger sensor will collect more light than a smaller sensor. It's like a bucket, the bigger the bucket the more water it can collect. This means that in low light situations, a higher resolution camera will tend to suffer from light issues that can lead to blurry images. Ironically, the resultant of this can lead to less clarity in your image.

So how do I know which resolution to use?

Fortunately, security integrators have been working with this technology for many years and have a pretty good grasp on where to apply it. A good provider will be able to advise you on the best camera fit for each application. It is good to have a basic understanding though, so with that said let's have a look at some applications.

Carparks and higher megapixel

Higher megapixel cameras are particularly good at minimising the need for multiple cameras. For instance, to cover a 50m x 50m carpark, you would have once needed multiple 2 megapixel cameras. An 8 megapixel camera (4K) with a wide angle lens can theoretically do the work of 4 x 2 megapixel cameras (depending on the layout of the carpark), potentially saving you the work and expense of installing 3 cameras. However the trade-off is less low light performance, so unless the carpark is reasonably well lit, you may find yourself looking at a dark or blurry screen.

Top tip - Think about the size of your space and the ambient light levels

Corridors and lower megapixel

Lower megapixel cameras may not give you the resolution; but they are much better in low light situations. A great example of where a lower megapixel camera is actually a better bet may be in an internal corridor. Remember the point of CCTV is to record and recognise an intruder, not make them look like a Hollywood star in 4K!! As a general rule of thumb, if you can see what you want to see, then any more pixels are just wasted. As a corridor is by nature quite narrow, there is no point having a high resolution image as most detail will be pretty clear at such close range. The real advantage comes into play when the lights go down. That low megapixel camera will give you far superior low light footage with less motion blur and/or graininess and a better framerate. This means your footage will actually be clearer and sharper with lower megapixels....how's that for irony!

Top tip - Consider how close the camera will be to the target

Storage is EXPENSIVE

Put simply, the more resolution, the more data and therefore the more storage needed in your recorder. Believe it or not, often in larger CCTV installations the storage required for the footage is actually more expensive that the cameras. That's because more cameras and higher resolution = more hard drives to store the footage. This in turn means that the recorder needed to manage all this needs to be more powerful to handle all the work of encoding and decoding that video onto a hard drive. It gets worse though.......this ALSO means that the networking infrastructure needed to handle all of this data on it's way to the recorded needs to be taken into account. A good provider will be able to take all this into account and optimise the system using framerates, resolution and picture quality setting among many other tools.

Top tip - Think about how many days footage you want to keep

Tips

• Beware of the security provider that proposes the same camera for every part of your building - they are not planning based on YOUR requirements
• NVRs almost NEVER live up to their specifications - a "4K" NVR usually means 1-2 cameras at 4K maximum is all it can handle
• Your security provider MUST have strong networking knowledge - ask questions to ensure they do

Hopefully the above info will help to make the decision a little easier. Follow the tips to ensure you get the right product installed and maintained by a professional security provider.

All the best!!

Kind Regards,

Adam Walsh
General Manager

Brave Security
9 Hall Street, Port Melbourne VIC 3207
13.000.THEFT (1300-084-338)
0423 456 472
www.bravesecurity.com.au