I needed to figure out the focal length of this camera in "real" camera equivalent and I thought I would share my results in case it helps someone else.
This
2016 camera has a sensor size of 1/2.8", which comes to
6.49 mm on the diagonal. To
calculate the "crop factor" for any camera sensor, you need to compare it to the full frame standard. A "full frame" camera has a sensor size of 43.3 mm. In this case, 43.3 / 6.49 = 6.67.
So, now we can multiply the listed focal length of 5.1 mm to 51 mm by 6.67 to get the equivalent focal length in terms of a "normal" 35 mm camera: 34 - 340 mm.
So, if you have a fancy full-frame DSLR, what Nikon calls an FX sensor, you can use a zoom lens in the 34 - 340 mm range to simulate the view of this PTZ camera.
If you have a "crop sensor" DSLR, what Nikon calls a DX sensor, you have a crop factor of ~1.5. To simulate the "normal" 34-340 mm on that sensor size, you'd need a lens with a range of ~22 mm - 220 mm.
If you know the sensor size of your particular camera, you fan figure out the "crop factor" as above, and then how that camera maps to the focal lengths of any security camera you're interested in using.
Whew!