2MP vs 4MP vs 8MP - day vs night ?

TundraCam

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A 4MP needs about twice as much light as a 2MP? However, can a 4MP operate as a 2MP? IOW, would it make any sense to get a 4MP or 8MP and have it at full rez during the day and then downrez at night?

Thanks,
 

mat200

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A 4MP needs about twice as much light as a 2MP? However, can a 4MP operate as a 2MP? IOW, would it make any sense to get a 4MP or 8MP and have it at full rez during the day and then downrez at night?

Thanks,
Hi @TundraCam

Not so simple as just looking at the Resolution / MegaPixels.

Sensor size is often one variable we also look at along with MegaPixels to help determine the "pixel size" .. then there are more variables to consider. ( lens, F stop, processing .. )

It does get complex when you really start to dig into it more, so for many people the simple answer is to look for the largest sensor camera for that resolution / pixel size, and check the reviews here if we have them.

Then look to tune your parameters, and appropriately place the camera to maximize the ( quality of the ) image.
 
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TundraCam

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Thanks. The funny thing is that I'm a fashion photographer - but this is an entirely different world.

Am I thinking correctly assuming the same sensor size and lens?

Or perhaps a better way to put it - same camera but 2, 4 or 8 MP with commensurate increases in cost. Will I loose any capability with a 4 or 8? E.G, should I still be able to downconfig them if necessary? I'm OK spending a few extra $'s to cover my bases (one reason most of my existing are vari-focal) but want to be careful not to loose capability (like buying a color camera that can't see IR).

This is for: Help w/ additional cameras ?
 
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sebastiantombs

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Rule of thumb for resolution versus sensor sizes -

720P - 1/3" = .333"
2MP - 1/2.8" = .357" (think a .38 caliber bullet)
4MP - 1/1.8" = .555" (bigger than a .50 caliber bullet or ball)
8MP - 1/1.2" = .833" (bigger than a 20mm chain gun round)
 

wittaj

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It is still using the 4 million pixels - the camera doesn't change the "pixel resolution screen" on the camera when you go from 4MP to 2MP. The sensor still needs 2 times the light going from 4MP to 2MP, so the native 2MP camera will result in a better image at night. The firmware will make some attempt at downrezing it, but it could be a complete crap image or a usable image, but if there is a concern that the 4MP isn't performing or wouldn't perform well at night, then it is better to go with the 2MP.

I have a 4MP and 2MP on the same 1/2.8" sensor and the picture quality is quite different between the two and the 2MP kicks it's butt at night.

In most instances, you want to get a camera that will perform at your location for the worse situation, which for most of us is at night when it is dark and there is little to no light. If a camera performs at night, it is easier to tweak settings to make it work during the day than it is the other way around.

My 2MP cameras outperform my neighbors 4K (8MP) cameras....why....because they are both on the same size sensor.

When we had a thief come thru here and get into a lot of cars, the police couldn't use one video or photo from anyone's system but mine. Not even my other neighbors $1,300 8MP system provided useful info - the cams just didn't cut it at night.

My neighbor tried the "I will just downrez the 8MP to 2MP" and the image was a soft dark mess.

His system wasn't even a year old and after that event has started replacing with cameras purchased from Andy here based on my recommendation and seeing my results. He is still shocked a 2MP camera performs better than his 4k cameras and he cannot figure out why downrezing from 8MP to 2MP doesn't work properly... It is all about the amount of light needed and getting the right camera for the right location and downrezing doesn't change the physics of the camera.

It is simple LOL do not chase MP - do not buy a 4MP camera that is anything other than a 1/1.8" sensor. Do not buy a 2MP camera that is anything other than a 1/2.8" sensor. Do not buy a 4K (8MP) camera on anything smaller than a 1/1.2" sensor. Unfortunately, most 4k cams are on the same sensor as a 2MP and thus the 2MP will kick its butt all night long as the 4k will need 4 times the light than the 2MP... 4k will do very poor at night unless you have stadium quality lighting (well a lot of lighting LOL).
 

TundraCam

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Thank you guys. I think it finally makes sense now.

There was a camera (I believe Phase One) that I played with a bit ago that had a low light mode that effectively took 4 pixels and used them as one with each a different bit of dynamic range. The result was effectively 18 stops of actual dynamic range which was quite amazing.
 
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