So almost everywhere you look now you will find people, especially on facebook forums recommending cheap 4k CCTV cameras, the latest and greatest at a bargain price! I mean why not, it’s more pixels and more detail, a quantifiable way of measuring how good it is vs the last generation.
However, one huge point is overlooked here by the uninformed and the reason why the top-rated videography camera, the Sony A7S 2 DSLR costing £2000 (without a lens) has only 12 megapixels while some mobile phones have been packing 40 megapixels plus (on a much smaller sensor).
The Sony a7S has a full frame sensor (a considerable 36 x 24mm = 864mm²) which is significantly bigger than the 1/1.25” sensor found on most budget CCTV cameras and mobile phones (a measly 5.76 x 4.29mm = 28mm²) – you then have to pack 8 million pixels into this 28mm2 (on a cheap 4k camera) making them each incredibly small thus comparably poor at capturing light, in low light settings.
The simple fact is smaller pixels capture less light = a useless dim and noisy image. Unless you open the shutter speed for longer as a way to compensate. Opening the shutter for longer is all well and good if photographing a still subject or if you wish to create an arty star trail photograph, but ideally not when you wish to capture the identity of an intruder in your back garden at night, as this introduces motion blur as we see here:
Source and more reading at: https://matryxconsulting.com.au/index.php/considering-4k-cctv-here-are-3-important-questions-you-need-to-ask/
So a cheap 4k CCTV camera may appear to provide a superb image in daylight and a respectable one at night, that is until you actually might want to use the cameras for the intended purpose when looking back at footage!
So does 4k have it's uses?
More megapixels allows for you to zoom in to a recording digitally (stretching it out on a 1080p display) to take a loser look at a smaller objects or a person in the background without loosing detail, this is of benefit for large well-lit areas. But for smaller areas around a house say, if the right lens is used to frame the area correctly this will not be at all necessary. Overall we find good quality mid-range 4MP/5MP cameras (such as the VALE Starlight Sensor series) provide a good compromise, although smaller budgets would get the best performance from a 2MP camera at night.
If you must go 4K spending a little more on one with a larger sensor size would go a long way.
More further reading: do not confuse frame rate and shutter speed, having a faster frame rate does not have the same effect: https://www.mediacollege.com/video/camera/shutter/shutter-vs-fps.html
Thanks for reading,
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