The Importance of Focal Length over MP in camera selection
- Thread starter wittaj
- Start date
mephisto_uk
Getting the hang of it
just curious, why are you digital zooming 5442-ZE 4MP ? doesn't this camera have motorized/optical zoom?Now what about daytime, can you get away with more digital zoom then?
So here are comparable daytime pics taken at the same time (noon) of the same vehicle from just slightly different angles - one from the 5442-ZE 4MP set to 3.6mm that I digitally zoomed to make the vehicle about the same size as the vehicle in the 2MP 5241-Z12E varifocal optically zoomed. You can make out the phone number in the 2MP optically zoomed picture, but not in the 4MP digitally zoomed picture.
As expected, with enough light, the digital zoom is more effective, but it isn't perfect either.
The 2MP camera is 4092 CBR bitrate and the 4MP is 8192 CBR bitrate, which are appropriate for their relative resolutions. Both at H264. H265 is even worse digital zoomed due to how it blocks for compression.
Digital zoom uses an algorithm to achieve that zoom and that also introduces additional noise and artifacts as the algorithm tries to fill in missing pieces and interpolate as the digital zoom gets bigger. It isn't like taking a magnifying glass to a hard copy of something. Digital zoom introduces artifacts not present in the original size.
Economically, the sensor size simply isn't available to us (nor would we want the size of the camera to accommodate it) to provide us with meaningful digital zoom beyond just a little bit.
I tested all of this when I got the camera by digital zooming to something across the street and changing bitrates until I saw a difference - I wanted to try to squeeze as much digital zoom as I could out of it, and the simple fact is you just can't do a lot.
By comparison, the non digitally zoomed 4MP image looks great and something within the DORI number for IDENTIFY looks great. But when you digital zoom, this is what you get, unless you are in a movie or on TV and then you are seeing nose hairs when digital zooming LOL.
There is a trade off with every camera. Do you want a wide field of view but lose details at distance, or a narrow field of view but able to get details at distance.
Most of us have a wide angle fixed camera as an overview to OBSERVE a wider view and can serve to IDENTIFY when a subject is within the DORI distance for that particular camera, supplemented with optical zoomed cameras zoomed in to pinch points or other points of interest further out.
Again, it is why we say one camera cannot do all, be all, see all. A 2.8mm or 3.6mm fixed cam is a great overview camera to get a big wide picture, but it isn't going to be used to IDENTIFY a stranger at 60 feet, especially at night. You need another camera optically zoomed to that area.
Yes, that camera has optical zoom, BUT the entire point of that post was to demonstrate DIGITAL zoom shortcomings by demonstrating that camera as a fixed 3.6mm 5442 and digital zooming.
Of course OPTICAL zoom the 5442 to the same area as the OPTICAL zoom of the 5241 and the 5442 would be better, but that isn't the point of this thread or that particular post.
The point is to demonstrate that focal length and OPTICAL zoom is much more important than chasing MP and then digital zooming.
I blame wittaj for weaning myself off the 4K MP addiction.
mephisto_uk
Getting the hang of it
Well, I ended up getting some 2MP instead of 4MP and in some cases this does not necessarily apply. The 5442s from Dahua are pretty good at night, some 2231 I've got are average at best, 5241 slightly better, but I should have got insteda 5442s, all of the 5442s I have for dark environments are much better than the 2MP cameras
While your statement is certainly true though as it relates to LPR - you are wrong as it relates to THIS thread LOL.
The entire purpose of this thread is to show how FOCAL length AKA OPTICAL zoom is more important than MP and DIGITAL zoom. And in some cases 2MP is the better option based on DISTANCE as the higher MP/sensor ratios are not available in the higher focal lengths.
The issue we see too many times is someone comes here with their fancy 4K 2.8 or 3.6mm camera and complains they cannot make out a face or plate at 60 feet away at night.
That is the problem. At 60 feet away, a larger focal length is needed and there isn't a 4K varifocal available (except in PTZ) on the proper MP/sensor ratio large enough for 60 feet, so a 5442-Z4E or 5241-Z12E will be the better choice for that distance.
But to clear up confusion some have, generally yes a higher MP camera on the ideal MP/sensor ratio for the same focal length will generally beat the lower MP camera at that same focal length for an object the same distance away. But we have also seen several people that are dissatisfied with the 4K cameras on the ideal MP/sensor ratio and feel like the 4MP 5442 camera is a better camera overall. I suspect some of the dissatisfaction relates to you still cannot digital zoom it at night.
So yes, a 4MP 5442 of the same fixed focal length will beat a 2MP 2231 or 5241of the same focal length. It is when you have maxed out the focal length of the 5442 or try to apply too much digital zoom that the higher focal length 2MP optically zoomed to the area of interest becomes the better choice. And don't mistake a brighter static image at night as a better image if one is comparing a fixed lens 5442 over an optical zoomed larger 2MP camera. The whole point is to get a clean capture of the perp, not nice bright static images and once digital zoom is applied to the brighter static image, it will become pixelated real quick, especially at night, and that is where the 2MP that is optically zoomed to the distance will be the better choice, even if the static image is darker.
The issue is the when the focal lengths are different.
As I showed in Post 16, here is a great example of two images taken at the same time (early AM while still dark out) of the same person 60 feet away from just slightly different angles - one from the 5442-ZE 4MP set to 3.6mm that I digitally zoomed to make the person about the same size as the person in the 2MP varifocal optically zoomed.
The digitally zoomed image of this 3.6mm focal length of a 4MP on the ideal MP/sensor ratio could not be used by police to IDENTIFY. This camera is added by white light AND infrared, so it is getting more total light than the 2MP.
Meanwhile this 2MP camera OPTICALLY zoomed with the higher focal length to capture IDENTIFY at this distance is better than the 4MP on the ideal MP/sensor ratio that was DIGITAL zoomed.
In case someone cannot figure it out, the 4MP that is digitally zoomed in is the B&W picture and the 2MP varifocal optically zoomed in is the color picture LOL.
I think most would agree that the optically zoomed 2MP picture beats the digitally zoomed 4MP picture - you can make out details and read some of the signage and make out bolts, etc. that are just a blur on the 4MP, which is being benefited by the same light the 2MP camera is getting plus the IR.
This is the point of this thread.
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mephisto_uk
Getting the hang of it
I have the 2231 varifocal, zoomed all the way, and a couple of 5241 3.6mm to cover the sides at closer distance this 2231 doesn't cover. I'm thinking about replacing all of them with 5442s. I have another 5442 zoom in another area that works pretty well, but not zoomed in all the way like the 2231. I think it is a combination of 2231 not being as good as the 5442 at night, plus the IR lights do not reach as far out.
I regret not budgeting more money to get 5442s all around.
I regret not budgeting more money to get 5442s all around.
Wow I just got Lectured, and before my morning coffee LOL, well I don't drink coffee but you beat my wife at lecturing me this morning...HahahaWhile your statement is certainly true though as it relates to LPR - you are wrong as it relates to THIS thread LOL.
The entire purpose of this thread is to show how FOCAL length AKA OPTICAL zoom is more important than MP and DIGITAL zoom. And in some cases 2MP is the better option based on DISTANCE as the higher MP/sensor ratios are not available in the higher focal lengths.
The issue we see too many times is someone comes here with their fancy 4K 2.8 or 3.6mm camera and complains they cannot make out a face or plate at 60 feet away at night.
That is the problem. At 60 feet away, a larger focal length is needed and there isn't a 4K varifocal available (except in PTZ) on the proper MP/sensor ratio large enough for 60 feet, so a 5442-Z4E or 5241-Z12E will be the better choice for that distance.
But to clear up confusion some have, generally yes a higher MP camera on the ideal MP/sensor ratio for the same focal length will generally beat the lower MP camera at that same focal length for an object the same distance away. But we have also seen several people that are dissatisfied with the 4K cameras on the ideal MP/sensor ratio and feel like the 4MP 5442 camera is a better camera overall. I suspect some of the dissatisfaction relates to you still cannot digital zoom it at night.
So yes, a 4MP 5442 of the same fixed focal length will beat a 2MP 2231 or 5241of the same focal length. It is when you have maxed out the focal length of the 5442 or try to apply too much digital zoom that the higher focal length 2MP optically zoomed to the area of interest becomes the better choice. And don't mistake a brighter static image at night as a better image if one is comparing a fixed lens 5442 over an optical zoomed larger 2MP camera. The whole point is to get a clean capture of the perp, not nice bright static images and once digital zoom is applied to the brighter static image, it will become pixelated real quick, especially at night, and that is where the 2MP that is optically zoomed to the distance will be the better choice, even if the static image is darker.
The issue is the when the focal lengths are different.
As I showed in Post 16, here is a great example of two images taken at the same time (early AM while still dark out) of the same person 60 feet away from just slightly different angles - one from the 5442-ZE 4MP set to 3.6mm that I digitally zoomed to make the person about the same size as the person in the 2MP varifocal optically zoomed.
The digitally zoomed image of this 3.6mm focal length of a 4MP on the ideal MP/sensor ratio could not be used by police to IDENTIFY. This camera is added by white light AND infrared, so it is getting more total light than the 2MP.
Meanwhile this 2MP camera OPTICALLY zoomed with the higher focal length to capture IDENTIFY at this distance is better than the 4MP on the ideal MP/sensor ratio that was DIGITAL zoomed.
In case someone cannot figure it out, the 4MP that is digitally zoomed in is the B&W picture and the 2MP varifocal optically zoomed in is the color picture LOL.
I think most would agree that the optically zoomed 2MP picture beats the digitally zoomed 4MP picture - you can make out details and read some of the signage and make out bolts, etc. that are just a blur on the 4MP, which is being benefited by the same light the 2MP camera is getting plus the IR.
This is the point of this thread.
But I do have a question, your two pics are comparing an Optically zoomed image to a Digitally zoomed image correct? Isn't that a bit unfair?
I have often thought of getting a PTZ with a high Optical Zoom but unless I am there at the time the video is recording Zooming in, I would only be able to Digitally Zoom in to the recorded video later anyway, correct? I am sure the PTZ CAMs are great if you are a Security Guard...
EDIT:
Ignore my ignorance above, after rereading your statement a Ding went off in my brain.
The entire purpose of this thread is to show how FOCAL length AKA OPTICAL zoom is more important than MP and DIGITAL zoom. And in some cases 2MP is the better option based on DISTANCE as the higher MP/sensor ratios are not available in the higher focal lengths.
Sorry, was not trying to derail this Thread, was actually, in a way, sharing. When I was looking for my LPR, I was suggested to buy a 2MP; Dahua HFW5241E-Z12E 2MP Starlight Varifocal Back then my mind set was to get the highest MP, as most new buyers do. Thanks to this Forum and you guys, I got the right CAM.
Oh I just want to say this Noob has very much enjoyed your Post, I have learned a whole lot from you...Thank You...
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Not necessarily.
I am still in the process of setting up my SD4A425DB-HNY, but instances like the video below is why I wanted to get an auto-tracking PTZ. None of the static cams on my house would have been able to capture any ID shots. While the primary purpose of my system is to monitor and protect the perimeter of my house, being able to pick up people on the other side of the street can be helpful to me.
As I was leaving I saw this guy walking down the street, his head darting from house to house, looking shady as all hell. If he had not been looking all over I think his hood would have obstructed his face, but at the same time, if he had not been looking all over I would have thought nothing of it and it probably would have been a non-issue.
He is actually a neighbor from around the corner. I don't know what he was doing, but I am sure I have looked just like him before as I walk through the neighborhood. I will sometimes look at all of the houses to see what they have going on, look for any excessive (normal...?) camera usage, just generally be nosy, etc.
Capture from the PTZ:
Capture from my 4K-X (3.6mm) over the driveway:
Wow, very nice. Yeah I looked at AUTO tracking too three years ago but the price back then I could almost buy 3-4 other CAMs with.
$400 is not bad at all now...
How High do you have it mounted, can you provide a picture of what it looks like mounted?
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Tons of photos in my thread here: Looking for advice on my install locations.
It's on the second floor soffit.
It's on the second floor soffit.
Thanks, yeah I only have a single story. I would have to mount it higher than my other CAMs that are under an 8 foot Eve, due to its size. BUT I do have a place where my LPR will be mounted that I could mount one...about 10 feet up...even though this is an old picture of our house and we only now have one tree, that may still be a problem, my LPR will be focused across our driveway away from our tree. I will check out your Thread, I want to see how good the AUTO is on that CAM. If I were to get one I would need it more at night...
Any future post about this AUTO CAM will be on your Thread so not to derail this Thread. I seem to somehow end up doing this a lot...
While your statement is certainly true though as it relates to LPR - you are wrong as it relates to THIS thread LOL.
The entire purpose of this thread is to show how FOCAL length AKA OPTICAL zoom is more important than MP and DIGITAL zoom. And in some cases 2MP is the better option based on DISTANCE as the higher MP/sensor ratios are not available in the higher focal lengths.
The issue we see too many times is someone comes here with their fancy 4K 2.8 or 3.6mm camera and complains they cannot make out a face or plate at 60 feet away at night.
That is the problem. At 60 feet away, a larger focal length is needed and there isn't a 4K varifocal available (except in PTZ) on the proper MP/sensor ratio large enough for 60 feet, so a 5442-Z4E or 5241-Z12E will be the better choice for that distance.
But to clear up confusion some have, generally yes a higher MP camera on the ideal MP/sensor ratio for the same focal length will generally beat the lower MP camera at that same focal length for an object the same distance away. But we have also seen several people that are dissatisfied with the 4K cameras on the ideal MP/sensor ratio and feel like the 4MP 5442 camera is a better camera overall. I suspect some of the dissatisfaction relates to you still cannot digital zoom it at night.
So yes, a 4MP 5442 of the same fixed focal length will beat a 2MP 2231 or 5241of the same focal length. It is when you have maxed out the focal length of the 5442 or try to apply too much digital zoom that the higher focal length 2MP optically zoomed to the area of interest becomes the better choice. And don't mistake a brighter static image at night as a better image if one is comparing a fixed lens 5442 over an optical zoomed larger 2MP camera. The whole point is to get a clean capture of the perp, not nice bright static images and once digital zoom is applied to the brighter static image, it will become pixelated real quick, especially at night, and that is where the 2MP that is optically zoomed to the distance will be the better choice, even if the static image is darker.
The issue is the when the focal lengths are different.
As I showed in Post 16, here is a great example of two images taken at the same time (early AM while still dark out) of the same person 60 feet away from just slightly different angles - one from the 5442-ZE 4MP set to 3.6mm that I digitally zoomed to make the person about the same size as the person in the 2MP varifocal optically zoomed.
The digitally zoomed image of this 3.6mm focal length of a 4MP on the ideal MP/sensor ratio could not be used by police to IDENTIFY. This camera is added by white light AND infrared, so it is getting more total light than the 2MP.
Meanwhile this 2MP camera OPTICALLY zoomed with the higher focal length to capture IDENTIFY at this distance is better than the 4MP on the ideal MP/sensor ratio that was DIGITAL zoomed.
In case someone cannot figure it out, the 4MP that is digitally zoomed in is the B&W picture and the 2MP varifocal optically zoomed in is the color picture LOL.
I think most would agree that the optically zoomed 2MP picture beats the digitally zoomed 4MP picture - you can make out details and read some of the signage and make out bolts, etc. that are just a blur on the 4MP, which is being benefited by the same light the 2MP camera is getting plus the IR.
This is the point of this thread.
This post is intriguing me a lot.
From my understanding we have two cameras under the same/similar conditions with very different results:
5442-ZE 4MP set to 3.6mm digitally zoomed (IPC-T5442T-ZE ?? turret) - BW picture above
- 4MP, 1/1.8" CMOS image sendor
- 0.003Lux at F1.8 Min. Illumination
- Built-in IR LED :40m(131.2 ft)(IR LED) illumination distance
- 4MP (2688 × 1520) @30 fps, 2MP(1920 × 1080) @60 fps
- $190 (turret)
- 2MP Starlight:1/2.8” 2MP progressive scan STARVIS CMOS
- 0.002 Lux at F1.5 minimum illumination
- 25/30 fps@1080P
- $250 (bullet, motorized lens)
While the purpose of the thread might be to show that optical zoom is better than more MP and Digital zoom (which I didn't really doubt in the first place), it also introduces the another significant difference between the two cameras:
Why does the 4MP require IR illumination and then does a horrible job even with that? Surely this can't be attributed to just the point of this thread: Digital zoom + 4MP vs Optical zoom + 2MP as I understand the "digital zoom" was done after the recording when the image was already black and white.
There must be something else at work here namely the other specs of the camera, and I'm suspecting the sensor size per MP: 0.178 vs 0.139 (or about 30% more light per pixel for the 2MP bullet camera due to the sensor).
This particular post with the purpose of this thread appears to say that a digitally zoomed 4MP camera image will be a messy B/W while an optically zoomed 2MP camera would stay in color. Is that the case?
This might not be the best thread to answer my question, but is there a thread that compares JUST the megapixels?
Particularly, I want to know if for the same sensor size a 4 MP camera will be penalized in low light conditions compared to a 2 MP camera, and if so, would the penalty be reduced if the 4 MP camera's resolution is reduced to the 2 MP equivalent, or the native resolution is what dictates the maximum performance?
OK, here comes a novel, so open up on a computer screen LOL
Regarding your question "Why does the 4MP require IR illumination and then does a horrible job even with that? Surely this can't be attributed to just the point of this thread: Digital zoom + 4MP vs Optical zoom + 2MP as I understand the "digital zoom" was done after the recording when the image was already black and white."
The answer is simple. The 4MP didn't require IR illumination - That camera was not set up to IDENTIFY at that distance, but rather up close within 10-15 feet of the camera and I CHOOSE to run it in B/W for the faster shutter to get a cleaner capture. That 4MP runs fine in color and is actually brighter than the 2MP.
This post was an afterthought long after those images were taken or I would have done a color to color comparison (but wait I have something close).
However, I am always tweaking my cams and will bounce back and forth between B/W and color and I happen to have a similar shot of the 4MP fixed lens in color from a different day.
So since you asked, the image on the left is the 4MP 5442 DIGITALLY ZOOMED in color (different day than the other two); the middle one is the 4MP 5442 DIGITALLY ZOOMED in B/W; and the right is the 2MP 5442 OPTICALLY ZOOMED and as you can see whether it was B/W or color, digital zoom doesn't provide as good of an image as the optical zoom.
So in theory, the 4MP B/W was at its best opportunity to get a clean digital image due to the white light and Infrared light it was getting and that is also kinda evident comparing the 4MP color versus B/W images.
So as you can see, your question "This particular post with the purpose of this thread appears to say that a digitally zoomed 4MP camera image will be a messy B/W while an optically zoomed 2MP camera would stay in color. Is that the case? " The answer is NO as this shows that whether it was in color or B/W, at night with limited light, it will be a messy digital zoomed image whether it is in color or B/W, but the B/W would stand a better chance due to seeing infrared light and an OPTICALLY zoomed camera will produce the best image for a set distance.
Regarding your question "Particularly, I want to know if for the same sensor size a 4 MP camera will be penalized in low light conditions compared to a 2 MP camera, and if so, would the penalty be reduced if the 4 MP camera's resolution is reduced to the 2 MP equivalent, or the native resolution is what dictates the maximum performance?"
The answer is an emphatic YES it will be penalized and downrezing a 4MP to 2MP does not work. The native resolution dictates the maximum performance.
A 4MP on the same size sensor as a 2MP will need DOUBLE the light of the 2MP.
Downrezing a camera does not work - 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 algorithm attempt at downrezing it, but it could be a complete crap image or a somewhat 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.
What you are failing to realize is there is more "pixel screen" material on the 4MP, so two cameras of different MP on the same size sensor will result in the higher MP having more opaque "screen" material that impacts how much light gets thru. So two different cams on same sensor means the lower MP will allow more light on the sensor.
Use a Window for example. Which one is clearer to look thru the one with a screen or one without? The more holes a screen is produced with, the more material there is as well.
These sensors are small and we need to get as much light to them as possible.
An analogy to try to understand why cameras need so much more light - let's look at an 8MP camera and this 8MP needs at least four times the amount of light as a 2MP for the same sensor. The sensor size is the same in each camera, but when you spread the "screen" of 8MP worth of pixel holes across the same sensor, it now has 4 times the holes, but also 4 times the "screen material" than the 2MP.
Kind of hard to explain, but lets try to use a window screen as an analogy - take a window where the opening is fixed - that is the sensor - you add a screen to it (that represents 2MP) and looking out through the screen is a little darker outside because of the screen material. Now replace that screen with one that has four times the amount of holes (now it represents 8MP) and it will be darker looking through it because (while the resolution would be better) there is a lot more screen material.
So if your house is like most where the top pane is glass with no screen and the bottom half is window with the screen and you see something outside during the daytime - do you sit down to look out through the screen or do you stand up to look a the object through the window with no screen?
And that is accentuated even more at night time. Look out your window with and without the screen and it will be darker looking through the screen than without it. If you are looking out your window to see the stars or the moon, do you look out the part of the window with the screen, or the upper portion without the screen material?
Now obviously as it relates to a camera, you need to balance the amount of pixel holes with the screen material - too few holes (and thus less screen material) and the resolution suffers, and too many holes (and thus more screen material) and the more light that is needed.
Look at a window screen and available meshes. The actual window opening does not change size, so that is the sensor. The screen material is the "pixel screen" that makes up the MP. Which one of these is going to let more light thru?
So if you are taking a 22 mesh screen and trying to get the same amount of brightness thru into the house as the 4 or 14 mesh screen, it will need A LOT more light.
A close comparison would be the 22 mesh screen is an 8MP and the 14 mesh is a 4MP. So if you have the same amount of light going thru a 14 mesh screen as you do a 22 mesh screen, it will be darker for the 22 mesh screen and any parameter adjustment you do to brighten it (gain, iris, brightness) will add more noise.
Even if the downrez from 4MP to 2MP happens before any other processing, it is still starting with a darker image than a native 2MP camera so that will introduce more artifacts.
This is how outside sun shades work. The darker/more shade it provides, the more holes the shade has. More holes equals more screen material which means more light that is needed to penetrate it.
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.
Now this is where you can see the difference about can a camera run in color or B/W for two different MP cameras on the same size sensor.
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 @EMPIRETECANDY 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.
Here is a real world example from a 2MP and 4MP model camera on the same size sensor.
Here is the 2MP on the 1/2.8" sensor. It deems it has enough light at a 1/60 shutter so it stays in color:
Here is the same camera model except it is a 4MP on the same 1/2.8" sensor as the 2MP above.
Here is the first big issue you see with a double the resolution on the same size sensor - It deems that it does not have enough light at a 1/60 shutter so it goes to B/W with Infrared:
So one thinks, "hey why don't I just make the 4MP camera a 2MP resolution and it will perform like a 2MP resolution camera" The first thing you notice is that downrezing the 4MP down to a 2MP doesn't result in the camera being able to run color like the native 2MP as the sensor still doesn't see enough light to run in color because the 4MP "pixel screen" simply isn't letting enough light get into the optics of the sensor.
That is a big deal with low light conditions and why you want to go with a native resolution and preferably a camera on the ideal MP/sensor ratio that is talked about here often. The native resolution may be able to be in color, but the higher resolution on the same size sensor probably won't with low light conditions.
Then in this case, you can see that the 4MP was struggling to even give definition compared to the 2MP. It is wet out so the rain reflections is wreaking havoc with the infrared and focus.
So when I downrezed but kept the bitrate the same, it still looks like a soft mess. Even if there is less noise in this instance, it still doesn't look as good as the native.
And the less light that is available, the bigger the difference one will see. Personally, for me the difference between being able to run it in color versus B/W is enough of a reason to go with the the camera that is on the ideal MP/sensor ratio talked about here so much.
As always YMMV.
Regarding your question "Why does the 4MP require IR illumination and then does a horrible job even with that? Surely this can't be attributed to just the point of this thread: Digital zoom + 4MP vs Optical zoom + 2MP as I understand the "digital zoom" was done after the recording when the image was already black and white."
The answer is simple. The 4MP didn't require IR illumination - That camera was not set up to IDENTIFY at that distance, but rather up close within 10-15 feet of the camera and I CHOOSE to run it in B/W for the faster shutter to get a cleaner capture. That 4MP runs fine in color and is actually brighter than the 2MP.
This post was an afterthought long after those images were taken or I would have done a color to color comparison (but wait I have something close).
However, I am always tweaking my cams and will bounce back and forth between B/W and color and I happen to have a similar shot of the 4MP fixed lens in color from a different day.
So since you asked, the image on the left is the 4MP 5442 DIGITALLY ZOOMED in color (different day than the other two); the middle one is the 4MP 5442 DIGITALLY ZOOMED in B/W; and the right is the 2MP 5442 OPTICALLY ZOOMED and as you can see whether it was B/W or color, digital zoom doesn't provide as good of an image as the optical zoom.
So in theory, the 4MP B/W was at its best opportunity to get a clean digital image due to the white light and Infrared light it was getting and that is also kinda evident comparing the 4MP color versus B/W images.
So as you can see, your question "This particular post with the purpose of this thread appears to say that a digitally zoomed 4MP camera image will be a messy B/W while an optically zoomed 2MP camera would stay in color. Is that the case? " The answer is NO as this shows that whether it was in color or B/W, at night with limited light, it will be a messy digital zoomed image whether it is in color or B/W, but the B/W would stand a better chance due to seeing infrared light and an OPTICALLY zoomed camera will produce the best image for a set distance.
Regarding your question "Particularly, I want to know if for the same sensor size a 4 MP camera will be penalized in low light conditions compared to a 2 MP camera, and if so, would the penalty be reduced if the 4 MP camera's resolution is reduced to the 2 MP equivalent, or the native resolution is what dictates the maximum performance?"
The answer is an emphatic YES it will be penalized and downrezing a 4MP to 2MP does not work. The native resolution dictates the maximum performance.
A 4MP on the same size sensor as a 2MP will need DOUBLE the light of the 2MP.
Downrezing a camera does not work - 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 algorithm attempt at downrezing it, but it could be a complete crap image or a somewhat 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.
What you are failing to realize is there is more "pixel screen" material on the 4MP, so two cameras of different MP on the same size sensor will result in the higher MP having more opaque "screen" material that impacts how much light gets thru. So two different cams on same sensor means the lower MP will allow more light on the sensor.
Use a Window for example. Which one is clearer to look thru the one with a screen or one without? The more holes a screen is produced with, the more material there is as well.
These sensors are small and we need to get as much light to them as possible.
An analogy to try to understand why cameras need so much more light - let's look at an 8MP camera and this 8MP needs at least four times the amount of light as a 2MP for the same sensor. The sensor size is the same in each camera, but when you spread the "screen" of 8MP worth of pixel holes across the same sensor, it now has 4 times the holes, but also 4 times the "screen material" than the 2MP.
Kind of hard to explain, but lets try to use a window screen as an analogy - take a window where the opening is fixed - that is the sensor - you add a screen to it (that represents 2MP) and looking out through the screen is a little darker outside because of the screen material. Now replace that screen with one that has four times the amount of holes (now it represents 8MP) and it will be darker looking through it because (while the resolution would be better) there is a lot more screen material.
So if your house is like most where the top pane is glass with no screen and the bottom half is window with the screen and you see something outside during the daytime - do you sit down to look out through the screen or do you stand up to look a the object through the window with no screen?
And that is accentuated even more at night time. Look out your window with and without the screen and it will be darker looking through the screen than without it. If you are looking out your window to see the stars or the moon, do you look out the part of the window with the screen, or the upper portion without the screen material?
Now obviously as it relates to a camera, you need to balance the amount of pixel holes with the screen material - too few holes (and thus less screen material) and the resolution suffers, and too many holes (and thus more screen material) and the more light that is needed.
Look at a window screen and available meshes. The actual window opening does not change size, so that is the sensor. The screen material is the "pixel screen" that makes up the MP. Which one of these is going to let more light thru?
So if you are taking a 22 mesh screen and trying to get the same amount of brightness thru into the house as the 4 or 14 mesh screen, it will need A LOT more light.
A close comparison would be the 22 mesh screen is an 8MP and the 14 mesh is a 4MP. So if you have the same amount of light going thru a 14 mesh screen as you do a 22 mesh screen, it will be darker for the 22 mesh screen and any parameter adjustment you do to brighten it (gain, iris, brightness) will add more noise.
Even if the downrez from 4MP to 2MP happens before any other processing, it is still starting with a darker image than a native 2MP camera so that will introduce more artifacts.
This is how outside sun shades work. The darker/more shade it provides, the more holes the shade has. More holes equals more screen material which means more light that is needed to penetrate it.
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.
Now this is where you can see the difference about can a camera run in color or B/W for two different MP cameras on the same size sensor.
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 @EMPIRETECANDY 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.
Here is a real world example from a 2MP and 4MP model camera on the same size sensor.
Here is the 2MP on the 1/2.8" sensor. It deems it has enough light at a 1/60 shutter so it stays in color:
Here is the same camera model except it is a 4MP on the same 1/2.8" sensor as the 2MP above.
Here is the first big issue you see with a double the resolution on the same size sensor - It deems that it does not have enough light at a 1/60 shutter so it goes to B/W with Infrared:
So one thinks, "hey why don't I just make the 4MP camera a 2MP resolution and it will perform like a 2MP resolution camera" The first thing you notice is that downrezing the 4MP down to a 2MP doesn't result in the camera being able to run color like the native 2MP as the sensor still doesn't see enough light to run in color because the 4MP "pixel screen" simply isn't letting enough light get into the optics of the sensor.
That is a big deal with low light conditions and why you want to go with a native resolution and preferably a camera on the ideal MP/sensor ratio that is talked about here often. The native resolution may be able to be in color, but the higher resolution on the same size sensor probably won't with low light conditions.
Then in this case, you can see that the 4MP was struggling to even give definition compared to the 2MP. It is wet out so the rain reflections is wreaking havoc with the infrared and focus.
So when I downrezed but kept the bitrate the same, it still looks like a soft mess. Even if there is less noise in this instance, it still doesn't look as good as the native.
And the less light that is available, the bigger the difference one will see. Personally, for me the difference between being able to run it in color versus B/W is enough of a reason to go with the the camera that is on the ideal MP/sensor ratio talked about here so much.
As always YMMV.
Thanks so much @wittaj for the clarifications. I was on the computer, so that's all good 
. You did repeat yourself a bit, but was an enjoyable read 
.
I was aware about the relationship between the sensor size and the camera's resolution and saw the chart and other info on this website, but the captures you added make the whole difference!
When searching (Google) for 4MP vs 8MP cameras, the answers are filled with (obvious) comparisons about the increased number of pixes and the resulting sharpness demonstrated with generated images, or captures in perfect conditions.
It was quite challenging to find something as definitive as your examples, in low light, that show how a 2 MP camera maintains its sharpness compared to 4 MP cameras (and we didn't even go to 4K).
So maybe a 4 MP or 8 MP camera would give nice pictures during daylight, it's the worst conditions that we have to plan for (as you rightly pointed out)
I'm still planning out my setup and I'm looking for the first camera to get familiar and experiment with. Unfortunately, your suggestions on the 2nd post are a bit expensive for trial, but at least I know what to look for and maybe a 2 MP camera is best as I can see for myself if 1080P is good enough for me (most my displays are still 1080p anyway).
EDIT: and for some reason, @EMPIRETECANDY doesn't carry any 2 MP cameras on the Canadian side: Amazon.ca, so will probably have to buy elsewhere.
. You did repeat yourself a bit, but was an enjoyable read .I was aware about the relationship between the sensor size and the camera's resolution and saw the chart and other info on this website, but the captures you added make the whole difference!
When searching (Google) for 4MP vs 8MP cameras, the answers are filled with (obvious) comparisons about the increased number of pixes and the resulting sharpness demonstrated with generated images, or captures in perfect conditions.
It was quite challenging to find something as definitive as your examples, in low light, that show how a 2 MP camera maintains its sharpness compared to 4 MP cameras (and we didn't even go to 4K).
So maybe a 4 MP or 8 MP camera would give nice pictures during daylight, it's the worst conditions that we have to plan for (as you rightly pointed out)
I'm still planning out my setup and I'm looking for the first camera to get familiar and experiment with. Unfortunately, your suggestions on the 2nd post are a bit expensive for trial, but at least I know what to look for and maybe a 2 MP camera is best as I can see for myself if 1080P is good enough for me (most my displays are still 1080p anyway).
EDIT: and for some reason, @EMPIRETECANDY doesn't carry any 2 MP cameras on the Canadian side: Amazon.ca, so will probably have to buy elsewhere.
Yeah most reviews you will find always show static images and usually on default settings. Any camera can look good with no motion. It is motion we are interested in, especially motion at night!
And most internet articles will favor higher MP and give daytime examples. How about a 2am example?
That is what makes this site different is that we are all sharing our own real world examples with our own cameras and showing how they perform in the situations we care about - a perp at 2am walking around.
Unlike most YouTube reviews, those of us that post here aren't getting commission or money based on our reviews. So ours tend to be more honest. Of course we have preferences and opinions on cameras, but that is based on our own personal usage and not based on recommending a camera based on getting a commission for every camera we push.
Many here will say 4MP is more than adequate for surveillance cameras.
The 5442-ZE is a great candidate to buy one and test it out. You can learn a lot from one camera and moving it around.
If 2MP is more your budget, the 3241 is a great choice as well to test and get familiar with them.
And most internet articles will favor higher MP and give daytime examples. How about a 2am example?
That is what makes this site different is that we are all sharing our own real world examples with our own cameras and showing how they perform in the situations we care about - a perp at 2am walking around.
Unlike most YouTube reviews, those of us that post here aren't getting commission or money based on our reviews. So ours tend to be more honest. Of course we have preferences and opinions on cameras, but that is based on our own personal usage and not based on recommending a camera based on getting a commission for every camera we push.
Many here will say 4MP is more than adequate for surveillance cameras.
The 5442-ZE is a great candidate to buy one and test it out. You can learn a lot from one camera and moving it around.
If 2MP is more your budget, the 3241 is a great choice as well to test and get familiar with them.
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You are always spot on!!
I've learned so much just by reading/re-reading.
I have another thread going under the "Mailbox Upgrade" , but thought I would add this here:
I just installed a B5442-SE , 1/1.8, 3.6mm (Due to finite size constraints only) and these petty juvy perps stalking my street aren't giving me time to get it dialed in at night.
This is a gang of three going thru mailboxes , I suppose looking for graduation/mother's day gift cards. Not that we get mail on Sunday's or anything like that, but it is what it is at 2:13am.
The LPR got the tag, and I gave that to the detective, but I just haven't got the near field motion dialed in yet due to limited time.
Yes, non moving objects are sharp, the perp in the picture is 110' away in very poor light (no streetlights). People walking by at night is sharp, but fast moving is still blurring, and of course headlights blind the camera head on.
Daytime 5442-SE pictures are awesome, I even can capture most tags even though not really needed (I live on a dead end street, the dedicated 5241E LPR captures all plates leaving day & night 24/7.)
