Understanding minimum illumination

Rack201

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Trying to understand min illumination. Looking at these two Dahua cams:

DH-IPC-HDW3888EMP-AS-AUS
DH-IPC-HDW3866EMP-S-AUS


(These seem to be Australia spec models - can’t find an equivalent in other markets)

The 3888 has a 1/1.8” sensor whereas a 1/2.8” sensor but ‘worse’ min illumination. I assumed low light performer should be better with a larger sensor size at the same MP rating.

Some suppliers list the 3866 as ‘starlight’ but can’t see that in the Dahua material?

thanks
 

wittaj

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Starlight is simply a marketing term.

Chase sensor size not MP. Two cameras of the same MP on different size sensors will result in the camera with the smaller sensor (1/2.8" is smaller than 1/1.8") not performing as well.

Regarding minimum illumination (LUX rating), many do not pay attention to the minimum illumination specs...because those are under ideal situations with so many factors not known.

Almost every camera will say 0 LUX with infrared or white LED on, and we all know how poorly Reolinks perform at night in low light yet that is their spec....or even two different good cameras. Take for example the 5442 4MP2.8mm fixed lens camera will beat the socks off the 5241 2MP 2.8mm fixed lens or a Reolink and they both say 0 Lux with IR on.

Heck darn near every camera will say 0 LUX with IR on....

Once upon a time manufacturers would at least say at what shutter speed that rating was based on. Most would say a 1/3 shutter. That is way to slow for anything. You need to run minimum 1/60 shutter to start to minimize blur.

But now they don't even provide that, so in most cases it is a wide open iris, slowest shutter the camera allows, and gain and brightness cranked to 100 so that they can get the lowest illumination number possible.

But nobody would run the camera in that configuration.

Some of the older cameras would give these kind of specs so you knew how the camera was setup to come up with the minimum illumination.

0.002Lux/F1.5 ( Color,1/3s,30IRE)
0.020Lux/F1.5 ( Color,1/30s,30IRE)
0Lux/F1.5 (IR on)

So of course, the faster the shutter, the more light that is needed, and thus the LUX needed is more.

To minimize blur with motion, you need to run a shutter at at least 1/60 shutter - once you start doing that, the LUX specs are out the window.

But as more competition came out, manufacturers started playing games and tweaking the settings for getting the lowest lux possible, but that came at a cost of a configuration nobody would use. So they wouldn't say how the camera was configured to capture that minimum illumination rating.

They play these marketing games to make it look like the camera is better than it is for someone that is just chasing minimum illumination numbers. Kind of like how we rarely get the miles per gallon a car is rated for.

It is a tool, but I would prefer to see the reviews here with settings provided and make an educated guess as to if my light is more or less than the reviewer.

You need to get a camera on the ideal MP/sensor ratio, which is anything in green:

Go with cameras that are on the ideal MP/sensor ratio:

1701206577445.png

So the 3888 camera that is 8mp on the 1/1.8" will perform much better than the 3866 camera that is 8mp on a much smaller 1/2.8" sensor that is designed for 2MP. At night the 3866 would need 4 times as much light as the 3888 to produce the same brightness image.
 
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Rack201

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Thank you for the lengthy reply. I’m an idiot and didn’t realise the sensor size was a fraction so the 3888 is the larger sensor. That chart is handy.
 

tigerwillow1

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I quit looking at the Minimum Illumination spec after buying a 2231 because it has a better spec than the 5231. The 5231 spec is 0.006 lux, and the 2231's spec is 0.002 lux. With both of them side-by-side, I can't see any difference in their low light performance.
 
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