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Infrared or IR Corrected Lenses use Low dispersion glass (LD glass) which is a type of glass that greatly reduces Chromatic Aberration. Chromatic Aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point or image plane as shown in the left image of (Fig. 1) Fig. 1 Different Types of LD Glass Listed Below: Special low dispersion glass (SLD glass) and extraordinary low dispersion glass (ELD glass) are glasses with yet lower dispersion (and yet higher price). Other glasses in this class are extra-low dispersion glass (ED glass), and ultra-low dispersion glass (UL glass). Standard lenses do not focus all frequencies, wavelengths or colors of light on to an image plane at the same location (Fig. 2). Standard lenses do focus most of the visible light on to the image plane but because CCD and CMOS image sensors are sensitive in the Infrared range your image will look softer or out of focus when Near Infrared and Infrared light is also prevalent in the captured scene (Fig. 3). The image on the color camera is not as blurry because the inherent design of color imaging cameras require an IR Cut Filter which is in place in these color images. This all holds true when using a Day/Night “Color/Monochrome” cameras. The IR Cut filter is removed when Day/Night cameras switches to Night or Monochrome mode. Fig. 2 Fig. 3 (Bright Sun / +100°F) This focus shift is mostly apparent in the Near Infrared and Infrared frequency range. When using a standard lens in a normal lighting condition and then switch to a dark condition with Infrared Illumination your image will become out of focus and refocusing the lens will be needed. Infrared or IR Corrected Lenses should be used on both color and monochrome cameras in all lighting conditions to achieve a crisp sharp image at all times.

We tested our 33X Zoom Lens from the rooftops of New York City. Check out the unbelievable detail and capabilities as we zoom in from over 2.6 Miles (13,800ft). You won’t believe the clarity and zoom of our Infrared Corrected, Day/Night OEM lenses! We used our HIR15-500M, 3 Mega Pixel, 15-500mm, Infrared Corrected, Auto-Focus, Motorized Zoom Lens to view the Empire State Building, MetLife Building, and a roof top party on the east side of Manhattan. We attached this lens to the Hitachi KP-D5010 High Resolution Day/Night camera to test the range and visibility using the various modes of the camera and this powerful lens. We also demonstrate its patented Auto-Focus feature. This lens is made using SD Glass (Special Low Dispersion Glass) to focus both the visible and infrared light onto the same focal plane (CCD Image Sensor). The SD Glass greatly reduces Chromatic Aberration, preventing muddy and “out of focus” images in “all” lighting conditions. SD Glass is a much higher quality low dispersion glass then the commonly found LD Glass (Low Dispersion Glass) used in consumer model Day/Night lenses. Features of this lens include: Optical Corrected Design Using SD Glass 3 Mega Pixel Clarity (No Spot Filter) Automatic Thermal Compensation System Motorized Selectable Filter System Auto-Focus Auto-Iris (Optional Spot Filter – F3.0-800) Presets RS-485/RS-232C Control Option