Which part of the light spectrum a lens lets through determines whether it works for daytime color, nighttime IR, or both — the switching itself happens in the camera, not the lens.
Most night-vision CCTV cameras pair an IR illuminator (LEDs emitting around 850nm or 940nm) with a sensor that's sensitive to that wavelength. The illuminator lights the scene invisibly to people, and the sensor picks it up as a black-and-white image.
Cameras vary in how they handle the transition between day and night. Many standard security cameras handle it internally, with a mechanical filter that physically moves in and out of the light path. Others expect the lens itself to define what part of the spectrum reaches the sensor at all times. That's why we offer lenses with different spectral characteristics rather than one universal option — the right one depends on what your specific camera already does on its own.
A lens that isn't designed for it can go soft at night: visible and infrared light bend by slightly different amounts through standard glass, so they focus at slightly different points — a lens sharp in daylight can go blurry once a camera switches to IR. Every lens in our catalog is IR-corrected, so focus stays consistent across whatever part of the spectrum that lens is built to pass, with no refocusing needed between day and night.
| Lens Type | What It Passes | Best For |
|---|---|---|
| Base lens (no suffix) | Full spectrum — visible + IR | Cameras that handle IR-cut switching internally, or monochrome/IR-illuminated setups |
| Fixed IR-cut (FA / IR650 suffix) | Visible light only | Daytime or always-lit color-only applications |
| Narrow dual-passband (e.g., IR850BP) | Visible light + a narrow IR band (e.g., 850nm) | Day and night operation with a matching IR illuminator, no mechanical switch needed |
| Pure bandpass (IR only) | Only a narrow IR band, no visible light | Covert/always-on IR imaging |
PT-1620BMP (base, full spectrum) and PT-1620BMPFA (fixed IR-cut, visible only) share the same focal length and optics — the difference is purely which part of the spectrum reaches the sensor, so the right pick depends on what your camera needs fed to it, not on image quality. For day-and-night operation without a mechanical switch, PT-02120-IR850BP passes visible light plus a narrow band at 850nm, matched to common IR illuminators.
Check whether your camera already handles IR-cut switching on its own — most standard day/night security cameras do, and a base lens works fine with those. If you need the lens itself to restrict to visible light only, or to pass a specific IR band, use the table above to match it to your setup.
Browse our full range of M12 and CS mount lenses, or check our guides on focal length and aperture to finish specifying your camera build.
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