What does the spec IFOV tell you?

• A. Instantaneous Field of View
• B. Instantaneously Field of View
• C. Infrared Field of View
• D. Integrated Field of View

Answer: (B)

IFOV tells you the area on the target that contributes to a single detector element’s reading at an exact moment. It’s the size of the footprint each pixel covers in the scene, described as an angular measure (usually milliradians or degrees). The actual size of that footprint on the ground depends on distance to the target: footprints scale with distance, so farther targets produce larger ground footprints for the same IFOV.

In practical terms, IFOV controls spatial resolution. A smaller IFOV means each pixel samples a smaller area, giving finer detail; a larger IFOV covers more area per pixel, reducing detail. The footprint size is roughly distance times the angle in radians (for small angles, footprint ≈ distance × IFOV). This is different from the overall field of view or from how long the sensor integrates signal.

Note that the standard term is Instantaneous Field of View. The concept describes the per-pixel, momentary scene coverage, not the entire camera scanning or integration behavior.