Longpass Lens Filter 420 nm, Select your size, passes all light above 406 nm

The Longpass Lens Filter 420 nm is a lens filter that passes wavelengths above 420 nm with a useful range between 406–1000 nm, while blocking shorter wavelengths. It attaches directly to a machine vision lens using the standard filter thread. By blocking unwanted light below the cutoff point, the filter improves contrast and makes features easier to see, even in challenging lighting.

Multiple thread sizes are available so you can match the filter to your lens.

How the LP420 Longpass Filters Work

A longpass filter blocks light below a defined cutoff wavelength and allows light above that point to pass. For the LP420 filter, wavelengths above 420 nm pass with high transmission, while light below 406 nm is strongly blocked.

Because it transmits from the visible region into the near-infrared (NIR) range, the LP420 filter is suitable for imaging systems that operate with broad-spectrum or mixed illumination.

Specification
Filter type	Longpass
Useful wavelength range	406-1000 nm

LP420 Longpass Filter Overview and Use Cases

The LP420 filter transmits light above its 420 nm cutoff wavelength, with a useful range extending to 1000 nm.

By removing ultraviolet and shorter visible wavelengths, it enhances image contrast and signal stability when used with light sources such as white LEDs, blue suppression lighting or broad-spectrum lamps.

The filter is well suited for machine vision, industrial inspection, laboratory setups, and other imaging systems that require controlled spectral separation.

Typical Applications:

·         UV and blue light suppression

·         Imaging under white or visible-light illumination

·         Surface or print inspection under mixed lighting

Key Benefits:

·         Passes wavelengths above 420 nm with high efficiency

·         Strong blocking below the cutoff wavelength

·         Better contrast and detail in camera images

·         Works well in stable and changing lighting conditions

·         Supports accurate and repeatable imaging tasks 

Compatibility with Lenses and Cameras

The LP420 filter can be attached to the front of most machine vision lenses, as these lenses typically feature a threaded mount for direct filter installation.

For systems using a C-mount lens on a USB3 camera or GigE camera, the filter can also be fitted within the C-mount interface rather than on the front of the lens.

This configuration is advantageous when the lens lacks a front filter thread.

Mounted between the camera and lens, the filter remains securely positioned in the optical path, preserving alignment and ensuring consistent image quality.

The LP420 filter offers versatility for various optical setups and can be integrated easily without modifying the existing camera or lens assembly

Our Longpass Lens Filter 420 nm is available in different sizes:

Since lens dimensions vary, the LP420 filter is available in several standard thread sizes making it suitable for both small format and larger lenses:

- C-mount filter

- 0.5 thread (pitch): M22.5×0.5, M25.5×0.5, M27×0.5, M30.5×0.5, M34×0.5, M35.5×0.5, M37×0.5, M37.5×0.5, M40.5×0.5

- 0.75 thread (pitch): M37×0.75, M43×0.75, M46×0.75, M49×0.75, M52×0.75, M55×0.75, M58×0.75, M60×0.75, M62×0.75, M67×0.75, M72×0.75 

If you plan to use a C-mount (CMT) filter thread, please fill out the form below for instant access to the mounting instructions and lens compatibility guide.

Order LP420 Longpass Filters

Select the Longpass Lens Filter 420 nm in the thread size you need. Contact us if you need help choosing the correct cutoff wavelength or size.