In addition to the sensor size, pixel pitch, and display resolution, the technical data sheet also lists other important specifications. Do you know which ones to pay attention to and how to tell them apart? Learn about all the key specs here. That way, you’ll know exactly what to look for when purchasing your next thermal imaging camera.
Field of view (FoV)
What is the field of view?
The field of view of a thermal imaging device (often abbreviated FoV) describes the size of the visible angle when looking through the device. In most cases, the field of view is expressed in meters per 100 meters. The larger the field of view, the wider the image, but the smaller the details. Conversely, the smaller the field of view, the narrower the image, but the greater the magnification of the details. As such, the field of view also determines the thermal imaging camera’s ideal use case – devices with a larger FOV provide a perfect overview when hunting in forested areas or while searching for previously downed game. A smaller FOV offers more range and is ideal for hunting in the open field, as it allows game to be reliably identified over longer distances. Our range of thermal imaging products includes devices with both large and small fields of view.
Optical magnification (digital zoom)
What level of zoom makes sense?
In the case of digital zoom, unlike zoom via the focal length, the image is enlarged by multiplying the pixels. The larger the sensor, the more detailed the image, and the better the zoom. This means that it all depends on the relationship between the resolution and the sensor. The DTI 3, for example, has four zoom levels that are perfectly matched to the resolution and the 17-micron pixel pitch sensor to deliver detailed images. With its higher resolution of 640 x 480 and a pixel pitch of 12 microns, the DTI 6 even offers a 10-step digital zoom that makes specific details visible even at the highest level of magnification.
Frame rate
What does frame rate mean?
The frame rate is indicated in Hertz (Hz) and describes how often the thermal imaging camera processes, optimizes, and updates an image per second. The higher the frame rate, the better the image when viewed in motion. To ensure a smooth image, the frame rate shouldn’t be lower than 25 Hz. All of our thermal imaging devices feature a frame rate of 50 Hz, delivering a high-contrast, wobble-free, optimal image with no lag for reliable game identification during night hunting.
NETD
What is NETD?
The detector sensitivity, also referred to as noise equivalent temperature difference (NETD), describes the temperature sensitivity of a thermal imaging camera. It is expressed in millikelvin (mK) and represents the smallest temperature difference that a thermal imaging device can detect. The lower the NETD value, the higher the sensitivity. The following scale can be used to classify NETD values:
<40 mK (Excellent)
<50 mK (Good)
<60 mK (Acceptable)
<80 mK (Satisfactory)
The ZEISS thermal imaging devices all have a NETD value <40mK and can therefore be rated as excellent. However, for the overall evaluation of the imaging performance of a thermal imaging device, the interaction of all components is crucial. At ZEISS, this is ensured by the ZSIP, which guarantees a particularly detailed image. While the NETD value is thus an important value when it comes to evaluating the quality of a thermal imaging device, it shouldn’t be viewed as a sole and isolated criterion when selecting a thermal imaging camera.
Aperture (f-number)
What is the aperture?
The aperture value or f-number indicates the ratio of the focal length to the diameter of a thermal imaging camera’s entrance pupil. The smaller this number, the larger the diameter of the lens, the more infrared radiation enters the device, and the higher the contrast and sharpness of the image.
