4MP advantage when used as 2MP

[Jurko]

Hi people,
I'm interested if someone can give me an advice. If I buy this Hikvision model: DS-2DE5425IW-AE
which has a 4MP, 1/2.5" sensor. If I configure the cam to give out only a 2MP image which I will stream to YouTube, will I have any advantage over, for example, a cheaper Hikvision model: DS-2DE4225IW-DE that has only a 2MP sensor(1/2.8" size)? Or will I maybe even experience some drawbacks of using 4MP in non-"native", lower, 2MP resolution?

Will the slightly bigger sensor(1/2.5") in the 4MP cam produce lower levels of noise in low light?
Also if I'm using it at a lower 2MP resolution will the digital zooming take advatage of 4MP?

Thank you all in advance!

 

[GCoco]

The bigger the sensor the better, but I doubt you will notice much of a difference if any between 1/2.5 and 1/2.8. It would be measurable but most likely not noticeable.

If you record at 2MP you will get 2MP. The digital zoom will not be better than a true 2MP.

 

[bp2008]

Can you not stream native 4MP to YouTube?

Anyway it should be possible in theory for a 4MP to produce a somewhat sharper image at 2MP than a native 2MP camera would. As for how much noise there will be, you'd need to compare the light sensitivity specs of each camera. Lower minimum illumination is better. e.g. 0.005 lux is better than 0.01 for low light performance.

 

[aristobrat]

As for how much noise there will be, you'd need to compare the light sensitivity specs of each camera. Lower minimum illumination is better. e.g. 0.005 lux is better than 0.01 for low light performance.

That's what's confusing to me. It looks like the both rate the same (and have Dahua Starlight-like ratings):

Min. illumination:
Color: 0.005 Lux @(F1.6, AGC ON)
B/W: 0.001 Lux @(F1.6, AGC ON)
0 Lux with IR

I can see the 2MP camera rating like that if the 1/2.8" sensor is the Sony STARVIS... it'd be exactly like a Dahua Starlight.

But I don't know how the 4MP one also rates the same. I can't find where Sony makes a STARVIS sized 1/2.5", and from all of the experiences people have posted about higher MP Dahua cameras w/ Starlight image sensors, they don't have lux ratings like above.

DS-2DE4225IW-DE - Hikvision Europe
DS-2DE5425IW-AE - Hikvision Europe

 

[bp2008]

I wonder how many official specification sheets are just guesses by whoever had to put together the marketing material, and how many are verifiable, based on tests and fact.