The Bandpass Lens Filter 650 nm is a lens filter designed to pass light with a peak wavelength of 650 nm and a useful range between 630–670 nm, while blocking all other wavelengths. It mounts directly onto a standard machine vision lens using the built-in filter thread. With a broad selection of thread sizes, the BP650 can be matched securely to a wide variety of lenses, ensuring stable optical performance in demanding machine vision environments. BP650 Narrow Bandpass Filter Overview Narrow bandpass filters function by transmitting only a defined portion of the light spectrum while blocking all other wavelengths. For the BP650, transmission exceeds 90% at the 650 nm peak, and stays above 80% throughout the 630–670 nm useful range, corresponding to a 40 nm FWHM (±5 nm). This narrower passband delivers precise spectral isolation for wavelength-critical imaging tasks. Specification Filter type Narrow Bandpass Peak wavelength 650 nm Peak wavelength color Red Useful wavelength range 630-670 nm Bandpass 650 nm Lens Filter Size Options Because lenses come in different sizes, the BP650 filter is available in several standard thread options, making it suitable for both compact 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 Using a C-mount (CMT) Filter Thread? Just fill out the form below to get instant access to the manual on how to mount it and see which lenses it’s compatible with! hbspt.forms.create({ portalId: "7372172", formId: "9b7a9007-56f1-47fe-8842-3e0b38317a2e", region: "eu1" }); BP650 Narrow Bandpass Filter Applications The BP650 is optimized for imaging centered at 650 nm, delivering high spectral selectivity that improves contrast and measurement repeatability. For monochrome cameras, the filter acts as a red-selective element, passing only the desired red wavelength region while blocking neighboring and complementary wavelengths. This follows a subtractive color-filtering principle, emphasizing red tones while reducing interference from other colors. Used with a white or broadband illumination source, the BP650 isolates a clean 650 nm band and provides: • stronger contrast • improved distinction of fine surface features • reduced sensitivity to ambient light • consistent, repeatable image quality These characteristics make it an excellent choice for machine vision inspection, color-based sorting, and precision optical measurement. Typical Applications for a 650 nm Bandpass Lens Filter • Red LED or red-laser illumination systems • Surface defect detection • Fluorescence or color-based inspection • Red-spectrum color enhancement and contrast analysis Adding the BP650 Filter to Your Machine Vision Setup Most machine vision lenses include a front-mounted filter thread, allowing the BP650 filter to be attached directly. If you are using a C-mount lens on a GigE camera or USB3 camera, the filter can also be placed inside the C-mount connection instead of on the front of the lens. This option is particularly useful when the lens lacks a front filter thread. Positioning the filter between the camera and lens keeps it fixed in the optical path, maintaining optical alignment and stable imaging performance. These flexible installation options make the BP650 easy to incorporate into existing setups without modifying your current camera or lens configuration. 650 nm Bandpass Filter: Advantages • High transmission at the 650 nm center wavelength• Strong blocking of wavelengths outside the target band• Enhanced contrast and cleaner signal output• Stable optical behavior across variable conditions• Reliable, repeatable performance for high-precision imaging tasks Find the BP650 Filter Best Suited to Your Optical Setup Select the BP650 narrow bandpass lens filter in the thread size that fits your lens. For assistance choosing the right size or wavelength, contact our technical team.