Flintstone61
Known around here
got it.
Doesn't your brain hurt with all this data in your head?
Doesn't your brain hurt with all this data in your head?
The Importance of Focal Length over MP in camera selection
- Thread starter wittaj
- Start date
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.
TL : DR...
More megapixels is better...
Yes, I was kidding.
@wittaj when you are digitally zooming are you using zoom on the camera, BI, or after it's recorded? I always understood it that any type of digital zoom should be done after the image (in this case video) is captured. Any type of digital zoom introduces error, and if done after you have more options how to "enhance" the image. This how I understood it for photos, video may be a little different?
That was digitally zoomed from recorded video. I freeze framed the video and took a snapshot of it and then zoomed in from that image.
Here are a couple of shots with a Dahua SD12203T-GH 2.7-8.1mm PTZ cam which is 2MP on a 1/2.8" sensor.
First shot is the 2.7mm wide angle shot.
The second is at full optical zoom of 8.1mm.
The third shot is full optical zoom and full digital zoom as done in the camera. I do not know what the lens equivalent would be here. I just zoomed it as far in as the controls would allow.
And here is the full optical zoom photo then zoomed in digitally in MS Photos to about the same view as the digital zoom within the cam. You can see additional digital artifacts.
First shot is the 2.7mm wide angle shot.
The second is at full optical zoom of 8.1mm.
The third shot is full optical zoom and full digital zoom as done in the camera. I do not know what the lens equivalent would be here. I just zoomed it as far in as the controls would allow.
And here is the full optical zoom photo then zoomed in digitally in MS Photos to about the same view as the digital zoom within the cam. You can see additional digital artifacts.
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Since this thread is about proper camera selection, I thought it would be good to mention a little bit about running cameras in color versus B/W.
While color is obviously preferred, sometimes we have field of views that just do not have enough light and need to be in B/W with infrared.
Like many here, I use both to help ensure maximum opportunities to capture a clean image.
While infrared is great, because it is in B/W, sometimes you can get cleaner captures for like a face or something, but color determination is way off, and some colors are problematic with infrared.
So I notice this non-descript plain white truck go by so I got suspicious:
So I pull up a color camera to see what is going on and this is the truck:
Now that you know it is a Kroger truck, you can kinda see it in the B/W photo, but wow!
Now imagine if this were someone that had damage done to say a parked car hit by this vehicle and all they had were B/W cameras going, nobody would suspect this truck!
If at all possible, one should try to run some overview cameras in color - even though they clearly are not for IDENTIFY purposes, they help paint a better picture as to color and some other details that may be lost with infrared and B/W.
While color is obviously preferred, sometimes we have field of views that just do not have enough light and need to be in B/W with infrared.
Like many here, I use both to help ensure maximum opportunities to capture a clean image.
While infrared is great, because it is in B/W, sometimes you can get cleaner captures for like a face or something, but color determination is way off, and some colors are problematic with infrared.
So I notice this non-descript plain white truck go by so I got suspicious:
So I pull up a color camera to see what is going on and this is the truck:
Now that you know it is a Kroger truck, you can kinda see it in the B/W photo, but wow!
Now imagine if this were someone that had damage done to say a parked car hit by this vehicle and all they had were B/W cameras going, nobody would suspect this truck!
If at all possible, one should try to run some overview cameras in color - even though they clearly are not for IDENTIFY purposes, they help paint a better picture as to color and some other details that may be lost with infrared and B/W.
I think there's a small mistake in one of the images in this listing: IPC-Color4K-X 3.6mm (I followed the link from page 1 here).
I think the temp. range should say "-40*C to +60*C".
I think the temp. range should say "-40*C to +60*C".
As an Amazon Associate IPCamTalk earns from qualifying purchases.
@wittaj This was a good read. Thanks.
I'm a little confused by this, because I looked up the model and the info on amazon and dahua says it's varifocal, not fixed. What am I missing?
Mike A.
Known around here
- May 6, 2017
- 4,141
- 6,945
It is vari-focal. He means fixed as in not a PTZ.
It does have "zoom" but that's intended to be set at whatever focal length desired for that location not zoomed in/out all the time.
It does have "zoom" but that's intended to be set at whatever focal length desired for that location not zoomed in/out all the time.
Thanks. I had just thought I was getting the concepts when I misunderstood that scentence and had to double check. Thanks for clearing that up.
spammenotinoz
Getting comfortable
Excellent write-up, spot on about optical over megapixels.
While there are exceptions, I have found the Tiny IR LEDs in cameras to be effective at short distances only. So if you require Optical Zoon, you will likely an additional targeted IR spotlight (preferably at an offset).
(Colour cams don't have this limitation, as long as the target is lit by light)
Added some pics to add to your point
two cams mounted next to each other, car is ~20 meters away (in motion)
1st cam is 4mp VR (Dahua T5442T-ZE ) with an optical zoom, set about half way. Second is a 4k fixed 2.8mm Hikvision DS-2CD2087G2-L(U)
The 4k is an overview cam, but for detail I go to the 4mp. (previously had a 4k VR, but found the 4mp much better at night)
While there are exceptions, I have found the Tiny IR LEDs in cameras to be effective at short distances only. So if you require Optical Zoon, you will likely an additional targeted IR spotlight (preferably at an offset).
(Colour cams don't have this limitation, as long as the target is lit by light)
Added some pics to add to your point
two cams mounted next to each other, car is ~20 meters away (in motion)
1st cam is 4mp VR (Dahua T5442T-ZE ) with an optical zoom, set about half way. Second is a 4k fixed 2.8mm Hikvision DS-2CD2087G2-L(U)
The 4k is an overview cam, but for detail I go to the 4mp. (previously had a 4k VR, but found the 4mp much better at night)
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Somewhere i think on here had a chart that had the MP and sensor sizes on one chart? Have you seen this or know what i am talking about?
It is linked in Post #2 of this thread:
Night time camera selection w/motion involved
Everyone shops for a camera with a different approach to what might be the best camera for their install. I always check MP against sensor size as a way to remove undesirable cameras from my search. Once I found a camera with a desirable MP and sensor combo, I would then dig deeper on FOV...
BAM! Thats It! Thanks a lot for that. I looked all night for that. Still trying to do my reading to help understand all this.It is linked in Post #2 of this thread:
Night time camera selection w/motion involved
Everyone shops for a camera with a different approach to what might be the best camera for their install. I always check MP against sensor size as a way to remove undesirable cameras from my search. Once I found a camera with a desirable MP and sensor combo, I would then dig deeper on FOV...ipcamtalk.com
So much to think about, and I'm so glad someone has done the thinking for me!
We installed our roadside camera initially just for motion notifications, but have recently felt the need to identify vehicles due to local crime (and the police constantly calling me to ask if I might have footage of suspicious vehicles!).
Ideally, I'd like to be able to at least read number plates night and day - ANPR or even NPR is probably not absolutely necessary - and also need to cover the driveway entrance and hopefully the mailbox.
Distance to these vehicles is approx 15m, and they will be travelling around 80km/h.
Currently using camera's IR lighting, but have toyed with the idea of mounting an illuminator on the corner of the shed (circled on left in image1), because I get far too many false alerts from raindrop reflections.
So, from what I'm reading, I need maybe 4MP, 1/1.8" CMOS, fast shutter, varifocal lens, small aperture... now all I need is the local suppliers here in NZ to let me filter their products by these specs and I'm good. Unfortunately...
I see most of your recommendations are Dahua, but it appears the local stockist only has the crappy 1/3" sensors. I'll keep looking for just the right combination, but if anyone can suggest some particular models of various brands that fit the bill, it would be great
(I'd consider a dedicated camera for cars, as well as the existing one, if I thought I could possibly feed an additional cable through the conduit that I spent so much time and effort digging in!)
We installed our roadside camera initially just for motion notifications, but have recently felt the need to identify vehicles due to local crime (and the police constantly calling me to ask if I might have footage of suspicious vehicles!).
Ideally, I'd like to be able to at least read number plates night and day - ANPR or even NPR is probably not absolutely necessary - and also need to cover the driveway entrance and hopefully the mailbox.
Distance to these vehicles is approx 15m, and they will be travelling around 80km/h.
Currently using camera's IR lighting, but have toyed with the idea of mounting an illuminator on the corner of the shed (circled on left in image1), because I get far too many false alerts from raindrop reflections.
So, from what I'm reading, I need maybe 4MP, 1/1.8" CMOS, fast shutter, varifocal lens, small aperture... now all I need is the local suppliers here in NZ to let me filter their products by these specs and I'm good. Unfortunately...
I see most of your recommendations are Dahua, but it appears the local stockist only has the crappy 1/3" sensors. I'll keep looking for just the right combination, but if anyone can suggest some particular models of various brands that fit the bill, it would be great
(I'd consider a dedicated camera for cars, as well as the existing one, if I thought I could possibly feed an additional cable through the conduit that I spent so much time and effort digging in!)
If you can not get what you need locally check with Andy. He is having a sale on security cameras. See his post and pricing at 2022 EmpireTech Thanksgiving Day and Black Friday Sales for details.
Check out this Thread:So much to think about, and I'm so glad someone has done the thinking for me!
We installed our roadside camera initially just for motion notifications, but have recently felt the need to identify vehicles due to local crime (and the police constantly calling me to ask if I might have footage of suspicious vehicles!).
Ideally, I'd like to be able to at least read number plates night and day - ANPR or even NPR is probably not absolutely necessary - and also need to cover the driveway entrance and hopefully the mailbox.
Distance to these vehicles is approx 15m, and they will be travelling around 80km/h.
Currently using camera's IR lighting, but have toyed with the idea of mounting an illuminator on the corner of the shed (circled on left in image1), because I get far too many false alerts from raindrop reflections.
So, from what I'm reading, I need maybe 4MP, 1/1.8" CMOS, fast shutter, varifocal lens, small aperture... now all I need is the local suppliers here in NZ to let me filter their products by these specs and I'm good. Unfortunately...
I see most of your recommendations are Dahua, but it appears the local stockist only has the crappy 1/3" sensors. I'll keep looking for just the right combination, but if anyone can suggest some particular models of various brands that fit the bill, it would be great
(I'd consider a dedicated camera for cars, as well as the existing one, if I thought I could possibly feed an additional cable through the conduit that I spent so much time and effort digging in!) View attachment 146312View attachment 146313
New to LPR? Considerations Before You Begin
Thought I would throw together a post on my experiences so far with LPR in an effort to help others that are considering running down that rabbit hole. There are some practical considerations you should know about LPR. I am approaching this from the position of using Blue Iris and Plate...
There are other LPR Threads too that are very informational...
This is the model I was lead to buy from the experts here: Dahua HFW5241E-Z12E 2MP Starlight Varifocal Bullet (LPR)
But it is best to post/ask your questions on one of the LPR Threads...
Also, why is that car driving on the wrong side of the road?
HTH
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That's the beauty of these being IP cameras and POE. If you have the means to get a switch at the other end of the conduit then you can add as many cameras as your switch can power.
CanCuba
Known around here
So much to think about, and I'm so glad someone has done the thinking for me!
We installed our roadside camera initially just for motion notifications, but have recently felt the need to identify vehicles due to local crime (and the police constantly calling me to ask if I might have footage of suspicious vehicles!).
Ideally, I'd like to be able to at least read number plates night and day - ANPR or even NPR is probably not absolutely necessary - and also need to cover the driveway entrance and hopefully the mailbox.
Distance to these vehicles is approx 15m, and they will be travelling around 80km/h.
Currently using camera's IR lighting, but have toyed with the idea of mounting an illuminator on the corner of the shed (circled on left in image1), because I get far too many false alerts from raindrop reflections.
So, from what I'm reading, I need maybe 4MP, 1/1.8" CMOS, fast shutter, varifocal lens, small aperture... now all I need is the local suppliers here in NZ to let me filter their products by these specs and I'm good. Unfortunately...
I see most of your recommendations are Dahua, but it appears the local stockist only has the crappy 1/3" sensors. I'll keep looking for just the right combination, but if anyone can suggest some particular models of various brands that fit the bill, it would be great
(I'd consider a dedicated camera for cars, as well as the existing one, if I thought I could possibly feed an additional cable through the conduit that I spent so much time and effort digging in!) View attachment 146312View attachment 146313
I've recently installed more cameras without running new cable nor lowering myself to using wifi. See if you can source these out your way:
This is my preferred option as the outside piece is only a Y-cable. The actual electronics stay inside with the NVR/switch:
The advantage to this style is the cameras can be further apart and just connected to the splitter with a regular cable. Downside is the device itself draws about 3W and does get a bit warm. Not hot but it does generate heat.
The first one is cheaper. Both have been installed for a month without any issue whatsoever. You do need to be mindful of how many watts each camera draws. With the second splitter (without the Y-cable) it's only rated for 8W per outgoing port. But I suspect that you can calculate your maximum wattage per NVR/switch port, subtract 3W (for the device itself) and then divide by 2 (number of ports).
Example: My Dahua NVR is rated for 25.5W per port.
25.5W - 3W = 22.5W
22.5W /2 = 11.25W
The first device (with the Y-cable) uses a port for each camera. And the device doesn't seem to draw any wattage itself. So I'm going to installed 2 IR illuminators powered off of one port.
Again, I've had zero issues with these and it's a good option if running another cable is problematic.
Hope this helps.
mephisto_uk
Getting the hang of it
How do you guys convert the zoom on the IPC-T5442T-ZE for example into focal length in mm? The web interface of the camera just gives me a slider that has a value from 0 to 2275, I guess I need to find a way to convert this into mm?
Top of the Forum, click the arrow drop down next to Tools. There is a calculator available there.