# how to set camera fov and focal lens independently?

I am going to set the blender camera as the real surveillance camera, which the focal lens and fov of real camera is 4mm and 69.9 degree.

Firstly, I manually set the focal len of blender to 4mm, the blender automatically set the fov to 140.53 in the perspective view, I changed the sensor width and height, it has the influence but still doesn't simulate the focal len and fov as the real camera I used.

Secondly I followed this post - How to simulate a real camera with blender, but in the panoramic view, I added a new camera, even the parameters (focal len, fov and sensor width height) are changed as shown the post, nothing happens.

I wondered why in the perspective view both focal len and fov are automatically changed? and why the change in the panoramic view doesn't change at all.

The blender version I am using is 2.7.9

This is the picture of focal len at 4mm below

This is the picture of focal len at 12mm below

Increasing the focal len will make the objects in far distance look bigger?

• Forgot to set the sensor? If you set the Sensor Size to ~5.6 as well, FOV is ~69.984. – brockmann Aug 21 '17 at 9:38
• Set the Focal Length first, then change the type to FOV, set your Sensor Size and you'll see that the FOV value changes accordingly. Understanding Focal Length and Field of View, TLDR: The focal length of a lens defines the lens’s angular field of view. What camera you are trying to emulate? Adding the type, manufacturer and lens of the camera might be useful. – brockmann Aug 21 '17 at 10:17
• @brockmann Thanks, I found the sensor size on the camera specification is 1/2.8', so it is estimated 8.9mm to input to blender, the factory told me the choice of focal lens is 4mm, 8mm, 12mm, the higher the focal lens, the further you can see in the picture. However when setting focal lens parameter in the blender, the small focal lens I set, the further the image will show, completely different from the factory told me, why – user824624 Aug 21 '17 at 13:43
• Typically 1/2.8” refers to a sensor size of about 0.19” x 0.14” (4.71mm x 3.54mm) – brockmann Aug 21 '17 at 14:57