Resolution vs FOV

[spixel]

Let's say you have an 8mp camera with 2.8mm lens, 100 degree FOV

What lens/FOV would you need with a 2mp camera to get the same pixel detail on the same subject in the distance. 6mm,8mm,12mm?

I know not all pixels are equal etc, but assuming they both have the same detail per pixel.

Probably easy to figure out but not got time to think about it

 

[bp2008]

8MP = 3840 x 2160
2MP = 1920 x 1080

2MP is half the horizontal and half the vertical resolution, and therefore you would need about half the FOV to have the same level of detail captured. e.g. 100 degree -> 50 degree.

Of course as you say not all pixels are equal. Some sensors are better than others, and some lenses are better than others. If you have a 4K camera with a sub-par lens then it might not perform as well as you'd otherwise think.

 

[spixel]

8MP = 3840 x 2160
2MP = 1920 x 1080

2MP is half the horizontal and half the vertical resolution, and therefore you would need about half the FOV to have the same level of detail captured. e.g. 100 degree -> 50 degree.

Of course as you say not all pixels are equal. Some sensors are better than others, and some lenses are better than others. If you have a 4K camera with a sub-par lens then it might not perform as well as you'd otherwise think.

So if the main focus of the recording was a good bit away from the mounting point, would you say go for an 8mp and get all the close up view, or a narrow fov 2mp?
DS-2CD2325FWD-I vs DS-2CD2385FWD-I

The price is very close

 

[bp2008]

The 8MP camera won't do as well in the dark due to smaller pixels. Probably not even as well as a 2MP of the same field of view. On the spec sheets it says 0.008 lux at F 1.6 for the 2MP and 0.01 lux at F 1.2 for the 8MP. However I think they cheated; based on the picture I don't think it is possible that the 8MP has an F 1.2 lens, so the low light performance isn't going to be as close as they are pretending it is.

In my experience, even having lots of external lighting won't make an 8 MP camera perform very well at night, and that is why I haven't bought a second 8MP.

 

[spixel]

The 8MP camera won't do as well in the dark due to smaller pixels. Probably not even as well as a 2MP of the same field of view. On the spec sheets it says 0.008 lux at F 1.6 for the 2MP and 0.01 lux at F 1.2 for the 8MP. However I think they cheated; based on the picture I don't think it is possible that the 8MP has an F 1.2 lens, so the low light performance isn't going to be as close as they are pretending it is.

In my experience, even having lots of external lighting won't make an 8 MP camera perform very well at night, and that is why I haven't bought a second 8MP.

There's a channel on youtube which has night videos of both cameras (and others from the range) The 8mp actually looks a good bit better than the 5mp, but I can't tell how good the 8mp really is compared to the 2mp since it was uploaded at 1080p





The 8mp looks like it mightn't be fully night yet as sky is grey, can't tell on 2mp. 2mp looks like it has better contrast but most likely because it was raining there. Hard to be certain but that 8mp looks like it could be a great choice.

Do you know if cameras with narrow fov have a different IR angle to focus better on further objects?