If the camera moves farther from the object while the spot size remains the same, the spot size ratio will

If the camera moves farther from the object while the spot size remains the same, the spot size ratio will

• A. Decrease
• B. Increase
• C. Stay the same
• D. Become negative

Answer: (B)

Distance-to-spot ratio is the idea being tested. It’s defined as the distance from the camera to the object divided by the spot size on the object. If you move the camera farther away while the spot on the object stays the same size, the distance increases but the spot size remains constant, so the ratio increases. For example, at 60 cm with a 2 cm spot, the ratio is 30; at 120 cm with the same 2 cm spot, the ratio is 60. A larger distance-to-spot ratio means less spatial detail in the thermal image.

Distance-to-spot ratio is the idea being tested. It’s defined as the distance from the camera to the object divided by the spot size on the object. If you move the camera farther away while the spot on the object stays the same size, the distance increases but the spot size remains constant, so the ratio increases. For example, at 60 cm with a 2 cm spot, the ratio is 30; at 120 cm with the same 2 cm spot, the ratio is 60. A larger distance-to-spot ratio means less spatial detail in the thermal image.