From the size of the object you want to shoot, you can calculate the necessary lenses.
The needed thing at this time is the size of the image pickup device of the camera and the distance to the object (WD).
For example, if you want to secure a vertical field of view of 300 mm with 1 m WD, how many millimeters should the f value be? (I will use a 1/2 inch camera.)
The image sensor size of 1/2 inch camera as follows.
f = (distance to object (mm) X vertical size of imaging device (mm) / vertical field of view
= (1000 mm X 4.8 mm) / 300 mm = 16 mm
Choosing a lens with f = 16 mm will ensure the desired vertical field of view.
You can calculate the horizontal field of view as well.
By the way, you can easily calculate the horizontal field of view.
If it is a square type imaging device, the aspect ratio is 4: 3 . Therefore, the horizontal field of view will be 400 mm without calculation.
We have various CCTV lenses available. Please check this for details.