Compare Model Drawings, CAD & Specs Availability Price
New 680520-001
FOLDIR 25-275mm f/5.5
FOLDIR 25-275mm f/5.5, High Durability

WFOV (25mm)

Pitch 640x480
15 µm 23.4°

NFOV (275mm)

Pitch 640x480
15 µm 2.0°


  • Type
    Continuous Zoom
  • Focal Length
  • F/#
  • Cold Stop FPA Distance
  • Cold Stop Clear Aperture
  • Back Focal Length
    23.37mm in air
  • Minimum Focus Range
  • Nuc (by defocus)
  • Focus Mechanism
  • Focus Time
  • Zoom Mechanism
  • Weight
    302 g
  • Dimensions
  • Drive Voltage
  • Current Consumption
    <0.5A average, 1.0A peak
  • Communication Interface
    RS485, RS422
  • Operating Temperature Range
    -32ºC to +71ºC
  • Storage Temperature Range
    -40ºC to +80ºC
  • Sealing
    IP67 front element only
  • Wavelength Region


FOLDIR 25-275mm f/5.5 Detection, Recognition & Identification (DRI) Range

DRI ranges enable one to easily estimate the maximum range that an object can be either detected, recognized or identified. It is important to note that these estimates are based solely on geometrical parameters – the target size, distance, lens focal length and camera detector pixel size. Signal level, detector sensitivity, atmospheric conditions and other factors are not considered!

The calculations used here are based on the “Johnson Criteria”. According to the Johnson Criteria, the minimum resolution, pixels on target, required to achieve a 50% probability for an observer to discriminate an object are:

  • Detection: An object is present – 2 pixels on target (Lower Bar)
  • Recognition: discern the type of object, a human vs. a vehicle – 8 pixels on target (Middle Bar)
  • Identification: discern specific objects, a man vs. a woman, a car model – 12.8 pixels on target (Upper Bar)

Note: Calculations used are based on “Johnson Criteria” | Real world performance may vary depending on the weather conditions. Assumptions: 23mK NETD (f/5.5) for MWIR cooled detectors | 30Hz frame rate | 50% detection probability | 0.2km-1 atmospheric attenuation coefficient | human ΔT = 5°C | vehicle ΔT = 2°C

High Performance Mid-Wave Focal Plane

Using advanced technologies, top-quality materials and unique coating techniques, together with innovative engineering and opto-mechanical designs, we have earned a reputation for excellent performance, durability and quality.

High-durability and Hard-carbon AR Coatings

Our highly abrasion-resistant, anti-reflective advanced optical coatings include several types of Hard Carbon coatings which provide maximum durability, energy transmission & minimal reflection. Our innovative coating technologies include:

  • Physical Vapor Deposition (PVD) – Thermal heating and electron gun
  • Ion Assisted Deposition (IAD) – Ion gun
  • Plasma Enhanced Chemical Vapor Deposition (PECVD) for DLC coatings

Passive Athermalized Lens Assembly

Our IR imaging lens assemblies incorporate passive athermalization of the lenses and opto-mechanical system to maintain the highest imaging performance over the full operating temperature range. We use advanced materials that enable unique athermalization properties and optomechanical designs that effectively compensate for optical variations over a wide temperature range.

IR Optics Production Site Virtual Tour




Contact Us illustration

Have questions? Require assistance?

Click below to to contact Ophir IR Optics and we'll get back with you shortly.

Contact Ophir IR Optics