IPVMU Certified | 03/05/14 03:20pm
They key here is to ignore the zoom power number, ie: 22X.
That number is a multiplier based on the widest field of view vs. the most narrow (telephoto). This slide from our IPVMU class on PTZs directly addresses this point:
For example, the 'Horizontal angle of view' for a camera might be 55.8° - 1.7°. This results in a 'zoom number' of 34X: (55.8° / 34 = ~1.7°)
Because 'zoom power' is a ratio, you could potentially have two cameras that both claim 34X zoom that are widely different. For example, I could have a camera with a 'horizontal angle of view' range of 84.0° - 2.5° with the same zoom number of 34X, and with everything else equal it would not zoom as far.
So to answer your question: Resolution and angle of view give you the answer, not zoom number. Even when comparing analog and IP PTZs, we start there.
This update "How far can a PTZ see?" is especially useful here, and I'd recommend reading through it!
Chesapeake & Midlantic
No. Knowing that the lens is a 10x or a 20x only tells you that it magnifies things ten times or twenty times. It doesn't tell you ten times what. A 4.8mm~48mm lens and a 10mm~100mm are both 10x zoom lenses but they'll both show you very different things. A 50mm lens on a 1/4" sensor will show you something very different than a 50mm lens on a 1/3" sensor.
Optical zoom in IP and analog cameras are fundamentally the same, except for one major differentiator - resolution.
The ability to 'see' things far away is dependent on the focal length (i.e., all things equal a PTZ with max focal length of 100mm will 'see' farther than one with 50mm). However, the greater resolution of IP MP PTZs allow them to see farther, even with short focal lengths. See: SD vs. HD PTZ Shootout
Thanks to all for your efforts I was just ask becasue I was afraid the the depth of view for the 2 camera will be very different or not
ok, i understand that i must focus on focal lens and resolution not no of optical zoom so i wonder now how can i know field of view for camera by know it is focal lens
Wow! How amazing is the human body with all the interacting "hardware" !!!!
Now think for a minute about an Eagles eyes. What a wonderful and amazing world we live in!
And then there is our sense of smell and how immensly greater is that of our canine best friends, around us all the time.
Thanks for the questions/answers comparing our eyes to ip cameras. We humans take so much for granted every day.