This is for the OP based on Roberts post of which I concur:
Yes there are some really crap cameras that have fixed settings; and this camera qualifies
C5: 160x120 resolution
Digital Camera Focus: Fixed
Thermal Sensitivity/NETD: At ambient temperature 59 to 95°F (15 to 35°C) and object temperature above 32°F (0°C)
32 to 212°F (0 to 100°C): ±5.5°F (±3°C)
Thermal Sensitivity/NETD: <70 mK
This all really sucks.
Distance is about the distance from the camera to the target (for the OP).
The primary concern is about atmospheric attenuation, but if you get too far away your camera will not record a small object if it falls below the spacial resolution capacity of the camera.
The only way a camera can compensate for distance is by changing the camera lens. Can’t do that here.
If you are recording a spot temperature, you must move as close to the target as you can and never have different colors in the spot measurement area. All cameras consider Multiple pixel data to come up with a measurement by averaging them. Crap cameras require bigger measurement tools because they require more pixels to average and the spacial resolution (space between the pixels) are further apart. This is where resolution/sensitivity comes in. All 160x120 cameras are not created equal.
These adjustments should always be performed before we put anything into a report, generally done on the computer. There are always things hidden in a scan that is not properly tuned. So in your camera auto tune your potential to miss stuff in plain sight is huge. There may be several targets in one scan, so that scan must be tuned for each target in that scan.
Hope you keep these facts in mind as you continue your thermal education. As Clint said, “A man must know his limitations”.