Lower resolution changing the focal length?

[NEITTech]

I've just had a DS-2CD2T87G2-L 4mm installed. Obviously it defaulted to 4k 3840*2160 and this is how it was positioned on the wall.

At the moment I'm running all my cameras at 1920*1080 but I noticed when changing this new camera to that resolution it is chopping the sides of the image off, almost like the lens has gone from 4mm to 6mm.

Is there a setting I'm missing? I haven't come across this before.

4k:

1080p:

 

[Phil]

I think it is just a factor of the relationship between the physical sensor size, and scaling to the aspect ratio of 1920 x 1080.
I don't think there is a 'fix'.

Any reason for not using the 4K resolution that you have paid for?

 

[NEITTech]

I think it is just a factor of the relationship between the physical sensor size, and scaling to the aspect ratio of 1920 x 1080.
I don't think there is a 'fix'.

Any reason for not using the 4K resolution that you have paid for?

1. It makes my workstation quite loud when I'm displaying cameras at 4k in iVMS-4200!
2. 1080p is just about good enough for my needs
3. I'm getting extra cameras so need to keep an eye on storage usage