Zeiss DTI 6/20 Thermal Imaging CameraThe DTI 6 20 Thermal Imaging Camera have a 20mm f 1. 0 lens that provides a thermal detection range of 1,099 yards and a field of view of 1,140' at 1,000 yards. That's a 22 x 16 angular view (horizontal x vertical). Need more range and less field? You could get the DTI 6 40 or just purchase the 40mm f 1. 0 lens as well and exchange them as the need arises. With the 40mm lens, you get double the range and half the field of view. With the DTI 6 20