All
Not an exhaustive post by any means but wanted to try and assist further on this topic.
* Long post incoming *
I’ve been asked a lot and see a lot of posts RE: more megapixels and if higher MP is better when it comes to these cams. Similarly people asking if other cams in the same series offer the same quality of image and performance such as if the 5A825 (new 8MP variant) is as good as others in the series. Therefore wanted to write a quick post here (cross posted in the 5A425 review as well due to both cameras being listed below) to try and help guide people to a better overall experience with their cams.
The key is to remember that you shouldn’t necessarily chase megapixels whether thats on fixed, variable, PTZ even broadcast cameras. Thats not to say that certain applications don’t need, require or benefit from higher MP count but you have to look deeper than that and understand the relationship to sensor, light, SOC and optics etc.
Another key to take away is to remember that not all cams are created equal in this regard and that even in the same camera series these key components and pairings change. These pairings will impact performance and that will play into overall image quality and in some cases make or break an install and its requirements for the set target zone.
For example take a look at all the cam variants below (a number of which we’ve spoken about in this and other threads). While it may appear that certain lens / sensor pairings are the same so when coupling to a similar sensor MP increase would only benefit, the answer is unfortunately it doesn’t.
Breaking this out further:
Smaller sensors see less light therefore a 1/2.8” will see less than a 1/1.8” and that means conversely that larger sensors capture more light for a set shutter / ISO / aperture. Now this isn’t necessarily a deal breaker by itself BUT then you have to take into account other things, a key one being pixel density. The amount of pixels you are featuring on a sensor. The smaller the sensor, the less space for a given set of pixels and therefore the more pixels you push through a small sensor the more dense it gets.
So what can this lead to, well apart from confusion for a lot of people, if we stick with smaller sensor you find that the more pixels you throw at it then the more you have to mitigate blur and noise in a pixel dense environment using slower shutter speeds. That can work to an extent but can severely ruin a night time capture depending on target you are focused on and necessary shutter speed required to capture it blur free
Another issue with pixel density (the more megapixels we’re cramming into the sensor) is that on smaller sensors you can get light leak between the adjacent pixels which contributes to sensor noise and is amplified or seen more easily in night video again.
You will also see issues with decreased dynamic range which is incredibly important in video and especially when dealing with shadow based areas.
So are larger sensors the way to go and always lead you to success……NO, not by themselves. Again its the pairing of optics (lens), sensor, SOC. While larger sensors combat a number of things listed above and also allow for a much better foreground/background separation in video (great for keeping track of a target with a PTZ) they can still be over crammed by not pairing MP’s to sensor properly. Indeed the best pairing is large sensor to relative MP’s so that you don’t end up overly dense and which will result in way better image quality regardless of aperture. Also remember that most vari-focal lenses have a variable aperture (F-stop) to them meaning which will also regulate and affect light. In these lenses that means you will have a brighter lens at full wide and a darker lens with full zoom (look at the cams above for example). Thats not to say that fixed aperture lenses don’t exist but they are not the norm.
So put this altogether and what does this mean (for those looking for the punchline) well you are ideally looking for a balance as I mentioned. In the case of cameras, the lower the ratio of MP’s to appropriate sensor size will result in a better overall image and certainly result (for the most part) in higher quality, more usable, less noise in night time work. An example of a bad pairing would be the 4K cams we saw early on with 8MP crammed onto a 1/2.8” sensor. The 1/1.8” versions improved that but I can tell you from experience that for 8MP you need a larger sensor still to truly drive great quality across conditions. At a push though 4K/8MP on a 1/1.8” if you are looking at current availability but no smaller.
I couldn’t end this post without also addressing light mitigation in security cams, provided by things like backlight and IR. First off, don’t use backlight, it artificially bumps the image at the cost of noise, stay away from this whenever possible. Daytime you have more to work with so WDR etc can be used there if you must.
Lets quickly look at IR light. While most cams feature IR light you have to look at the distance this is rated for vs your install location. In a number of instances you’ll find people placing cams and assuming the IR will reach further than stated which it can’t. On the flip side you’ll also generally need to shave off about 30’ to 50’ of the stated IR distance in real-world use. Lastly when it comes to PTZ’s with long focal lengths you also need to pay attention to number of IR LED’s and layout. For example looking at the cams above, a number feature 4 IR LED’s but layouts differ by model and you sometimes find that the further distance you are pushing in IR power with fewer IR LED’s can lead to a cone (flashlight beam) effect. This will concentrate light into a spot for more night penetration at the expense of sharp fall off. This can be mitigated (on non pixel dense cams with larger sensors
) by adjusting IRIS etc as although noise is increased it can be mitigated. This brings balance to your scene but use sparingly and at the right time because do this with small, pixel dense cams and you end up with a ton of noise that can ruin an image.
* For a great IR setup take a look at the 49225, more IR LED’s, different layout, less stated distance = generally better more balanced coverage at night. The 5A425 also gets away with less IR LED’s due to the larger sensor (more light) and slightly brighter optic pairing but this is the limit you would want to go (from a pairing perspective) for 4MP. Therefore others outside of this on the list generally don’t perform as well and the 8MP would concern me UNLESS there were changes to the sensor and SOC for that cam. *
So back to the cams above. Based on everything I said, what would I recommend, 2 clear winners based on the info and on experience of these cams (except the new 8MP 5A). Personally on the assumption that the 8MP would be using the same SOC, sensor etc (based on specs), I would not expect this to be a high performant PTZ but if I get one will certainly test. My recommendations therefore are:
The 4MP for this 1/1.8” sensor (in the 5A) is the highest I would want to see in this pairing. The same goes for the 2mp on the 1/2.8”. These 2 cams are really good in these configurations. Conversely, the 5A445 as an example is unfortunately terrible for night vision in my testing and I personally would not recommend that one whereas its small brother, the 5A425, exceptionally well balanced.
While there are some great 8MP cams out there, it again all comes does to the pairing. So while the 1/1.8” pairing on the 7842 Ultra is extremely good, remember that its paired to a bright F1.2 lens which is very different to an 8MP paired to a 1/2.8” with an F1.6 for example. Just some things for all to bear in mind, again, not all cams are created equal and MP to sensor size should be a key consideration amongst others listed above when selecting a cam.
If people find this useful I may just separate this out as a single thread but thought it may be useful to mention the Dahua cams above.
HTH
Not an exhaustive post by any means but wanted to try and assist further on this topic.
* Long post incoming *
I’ve been asked a lot and see a lot of posts RE: more megapixels and if higher MP is better when it comes to these cams. Similarly people asking if other cams in the same series offer the same quality of image and performance such as if the 5A825 (new 8MP variant) is as good as others in the series. Therefore wanted to write a quick post here (cross posted in the 5A425 review as well due to both cameras being listed below) to try and help guide people to a better overall experience with their cams.
The key is to remember that you shouldn’t necessarily chase megapixels whether thats on fixed, variable, PTZ even broadcast cameras. Thats not to say that certain applications don’t need, require or benefit from higher MP count but you have to look deeper than that and understand the relationship to sensor, light, SOC and optics etc.
Another key to take away is to remember that not all cams are created equal in this regard and that even in the same camera series these key components and pairings change. These pairings will impact performance and that will play into overall image quality and in some cases make or break an install and its requirements for the set target zone.
For example take a look at all the cam variants below (a number of which we’ve spoken about in this and other threads). While it may appear that certain lens / sensor pairings are the same so when coupling to a similar sensor MP increase would only benefit, the answer is unfortunately it doesn’t.
49225XA-HNR (cam reviewed here) - 1/2.8” 2MP Sensor with 25x F1.6 to F4.4 lens
4GB ROM, 1GB RAM
Color: 0.005 @ F1.6
B&W: 0.0005 @ F1.6
IR Distance: 328’
IR LED’s: 6
49425XB-HNR - 1/2.8” 4MP Sensor with 25x F1.6 to F4.0 lens
4GB ROM, 1GB RAM
Color: 0.005 @ F1.6
B&W: 0.0005 @ F1.6
IR Distance: 328’
IR LED’s: 4
5A425XA-HNR - 1/1.8” 4MP Sensor with 25x F1.6 to F4.0 lens
4GB ROM, 1GB RAM
Color: 0.001 @ F1.6
B&W: 0.0001 @ F1.6
IR Distance: 492’
IR LED’s: 4
5A445XA-HNR - 1/2.8” 4MP Sensor with 45x F1.6 to F4.95 lens
4GB ROM, 1GB RAM
Color: 0.005 @ F1.6
B&W: 0.0005 @ F1.6
IR Distance: 492’
IR LED’s: 4
5A825-HNR - 1/1.8” 8MP Sensor with 25x F1.6 to F4.0 lens
8GB ROM, 2GB RAM
Color: 0.005 @ F1.6
B&W: 0.0005 @ F1.6
IR Distance: 492’
IR LED’s: 4
Breaking this out further:
Smaller sensors see less light therefore a 1/2.8” will see less than a 1/1.8” and that means conversely that larger sensors capture more light for a set shutter / ISO / aperture. Now this isn’t necessarily a deal breaker by itself BUT then you have to take into account other things, a key one being pixel density. The amount of pixels you are featuring on a sensor. The smaller the sensor, the less space for a given set of pixels and therefore the more pixels you push through a small sensor the more dense it gets.
So what can this lead to, well apart from confusion for a lot of people, if we stick with smaller sensor you find that the more pixels you throw at it then the more you have to mitigate blur and noise in a pixel dense environment using slower shutter speeds. That can work to an extent but can severely ruin a night time capture depending on target you are focused on and necessary shutter speed required to capture it blur free
Another issue with pixel density (the more megapixels we’re cramming into the sensor) is that on smaller sensors you can get light leak between the adjacent pixels which contributes to sensor noise and is amplified or seen more easily in night video again.
You will also see issues with decreased dynamic range which is incredibly important in video and especially when dealing with shadow based areas.
So are larger sensors the way to go and always lead you to success……NO, not by themselves. Again its the pairing of optics (lens), sensor, SOC. While larger sensors combat a number of things listed above and also allow for a much better foreground/background separation in video (great for keeping track of a target with a PTZ) they can still be over crammed by not pairing MP’s to sensor properly. Indeed the best pairing is large sensor to relative MP’s so that you don’t end up overly dense and which will result in way better image quality regardless of aperture. Also remember that most vari-focal lenses have a variable aperture (F-stop) to them meaning which will also regulate and affect light. In these lenses that means you will have a brighter lens at full wide and a darker lens with full zoom (look at the cams above for example). Thats not to say that fixed aperture lenses don’t exist but they are not the norm.
So put this altogether and what does this mean (for those looking for the punchline) well you are ideally looking for a balance as I mentioned. In the case of cameras, the lower the ratio of MP’s to appropriate sensor size will result in a better overall image and certainly result (for the most part) in higher quality, more usable, less noise in night time work. An example of a bad pairing would be the 4K cams we saw early on with 8MP crammed onto a 1/2.8” sensor. The 1/1.8” versions improved that but I can tell you from experience that for 8MP you need a larger sensor still to truly drive great quality across conditions. At a push though 4K/8MP on a 1/1.8” if you are looking at current availability but no smaller.
I couldn’t end this post without also addressing light mitigation in security cams, provided by things like backlight and IR. First off, don’t use backlight, it artificially bumps the image at the cost of noise, stay away from this whenever possible. Daytime you have more to work with so WDR etc can be used there if you must.
Lets quickly look at IR light. While most cams feature IR light you have to look at the distance this is rated for vs your install location. In a number of instances you’ll find people placing cams and assuming the IR will reach further than stated which it can’t. On the flip side you’ll also generally need to shave off about 30’ to 50’ of the stated IR distance in real-world use. Lastly when it comes to PTZ’s with long focal lengths you also need to pay attention to number of IR LED’s and layout. For example looking at the cams above, a number feature 4 IR LED’s but layouts differ by model and you sometimes find that the further distance you are pushing in IR power with fewer IR LED’s can lead to a cone (flashlight beam) effect. This will concentrate light into a spot for more night penetration at the expense of sharp fall off. This can be mitigated (on non pixel dense cams with larger sensors
) by adjusting IRIS etc as although noise is increased it can be mitigated. This brings balance to your scene but use sparingly and at the right time because do this with small, pixel dense cams and you end up with a ton of noise that can ruin an image.* For a great IR setup take a look at the 49225, more IR LED’s, different layout, less stated distance = generally better more balanced coverage at night. The 5A425 also gets away with less IR LED’s due to the larger sensor (more light) and slightly brighter optic pairing but this is the limit you would want to go (from a pairing perspective) for 4MP. Therefore others outside of this on the list generally don’t perform as well and the 8MP would concern me UNLESS there were changes to the sensor and SOC for that cam. *
So back to the cams above. Based on everything I said, what would I recommend, 2 clear winners based on the info and on experience of these cams (except the new 8MP 5A). Personally on the assumption that the 8MP would be using the same SOC, sensor etc (based on specs), I would not expect this to be a high performant PTZ but if I get one will certainly test. My recommendations therefore are:
2MP PTZ - 49225XA-HNR - 1/2.8” 2MP Sensor with 25x F1.6 to F4.4 lens
4MP PTZ - 5A425XA-HNR - 1/1.8” 4MP Sensor with 25x F1.6 to F4.0 lens
The 4MP for this 1/1.8” sensor (in the 5A) is the highest I would want to see in this pairing. The same goes for the 2mp on the 1/2.8”. These 2 cams are really good in these configurations. Conversely, the 5A445 as an example is unfortunately terrible for night vision in my testing and I personally would not recommend that one whereas its small brother, the 5A425, exceptionally well balanced.
While there are some great 8MP cams out there, it again all comes does to the pairing. So while the 1/1.8” pairing on the 7842 Ultra is extremely good, remember that its paired to a bright F1.2 lens which is very different to an 8MP paired to a 1/2.8” with an F1.6 for example. Just some things for all to bear in mind, again, not all cams are created equal and MP to sensor size should be a key consideration amongst others listed above when selecting a cam.
If people find this useful I may just separate this out as a single thread but thought it may be useful to mention the Dahua cams above.
HTH
I haven't painted a PTZ but have painted bullet cams. I found a can of spray on bedliner works great and is durable. 
