Choosing between 4MP IP Camera Vs. 8MP AHD Camera?

benkyearn

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Hello everyone, I'm new here. I would like to compare between cameras that are connected to DVR using BNC cable (maybe it's called AHD) Vs. IP cameras.
I have two available options are 4 MP for IP cameras and 8 MP for AHD cameras. Which one has a clearer image (like the ability to see small things like car number plate from long distances)? How much does the size of the lens affect (like 2.8mm or 3.6mm or variable up to 12mm)? I know the bigger the better but what If I have those two different megapixels (4 & 8)? Should I choose the lower MP with higher mm lens or what?
 

sebastiantombs

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Rather than chase megapixels you should chase sensor size. Remember that those are expressed as fractions so a 1/1.8" sensor is larger than a 1/2.8" sensor, The "sweet spots" are a 1/2.8" sensor on a 2MP camera and 1/1.8" sensor on a 4MP camera. An 8MP camera needs a 1/1.1" sensor, minimum, to produce a decent video, with motion, at night.

LPR is actually an art and there's a whole thread on it here. Basically, it takes a dedicated camera, usually two to catch front and rear plates, with a field of view that is limited to just the vehicle. At night, the view is black unless there's a vehicle in the shot and even then all that can be seen is the head/tail lights and the plat due to a shutter speed of 1/1000 or 1/2000. LPR and zoom in real life is not what you see in movies and on TV where editing and special effects make it look sooooo easy to do.

 

wittaj

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The popular 2.8mm wide angle will let you see a lot, but not be able to identify a lot...

To identify someone with the 2.8mm lens that is popular, someone would have to be within 13 feet of the camera, but realistically within 10 feet after you dial it in to your settings.

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My neighbor was bragging to me how he only needed his four 8MP 2.8mm fixed lens cams to see his entire property and the street and his whole backyard. His car was sitting in the driveway practically touching the garage door and his video quality was useless to ID the perp not even 10 feet away.....why....because the 8MP was on the same sensor size as what a 2MP camera has, so it needed way more light than he had available.

Here are my general distance recommendations, but switch out the Dahua 5442 series camera to the equivalent 2MP on the 1/2.8" sensor or equivalent Hikvision works as well.
  • 5442 fixed lens 2.8mm - anything within 10 feet of camera OR as an overview camera
  • 5442 ZE - varifocal - distances up to 40-50 feet (personally I wouldn't go past the 30 foot range but I like things closer)
  • 5442 Z4E - anything up to 80-100 feet (personally I wouldn't go past 60 feet but I like things closer)
  • 5241-Z12E - anything from 80 feet to almost 200 feet (personally I wouldn't go past 150 feet because I like things closer)
  • 5241-Z12E - for a license plate cam that you would angle up the street to get plates up to about 175 feet away, or up to 220 with additional IR.
  • 49225 PTZ - great PTZ and in conjunction with an NVR or Blue Iris and the cameras above that you can use as spotter cams to point the PTZ to the correct location to compliment the fixed cams.
You need to get the correct camera for the area trying to be covered. A 2.8mm to IDENTIFY someone 40 feet away is the wrong camera regardless of how good the camera is. A 2.8mm camera to IDENTIFY someone within 10 feet is a good choice OR it is an overview camera to see something happened but not be able to identify who.

Main keys are you can't locate the camera too high (not on the 2nd story or above 7 feet high unless it is for overview and not Identification purposes) or chase MP and you need to get the correct camera for the area trying to be covered. A 2.8mm to IDENTIFY someone 40 feet away is the wrong camera regardless of how good the camera is. A 2.8mm camera to IDENTIFY someone within 10 feet is a good choice OR it is an overview camera to see something happened but not be able to identify who. Also, do not chase marketing phrases like ColorVu and Full Color and the like - all cameras need light - simple physics...

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).

Sensor sizing can confuse a lot of people LOL.

Is a 1/2.8" sensor bigger than a 1/1.8" sensor? Most people say yes LOL. But it is a fraction, so the 1/1.8" sensor is the bigger of the two.

If you want to see things far away, you need optical zoom, digital zoom only works in the movies and TV...

Regarding a camera for LPR - keep in mind that this is a camera dedicated to plates and not an overview camera also. It is as much an art as it is a science. You will need two cameras. For LPR we need to zoom in tight to make the plate as large as possible. For most of us, all you see is the not much more than a vehicle in the entire frame. Now maybe in the right location during the day it might be able to see some other things, but not at night.

At night, we have to run a very fast shutter speed (1/2,000) and in B/W with IR and the image will be black. All you will see are head/tail lights and the plate. Some people can get away with color if they have enough street lights, but most of us cannot. Here is a representative sample of plates I get at night of vehicles traveling about 45MPH:


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