Ultraviolet Bandpass Clip-in Filter For Sigma FP/BF L-Mount – Magnetic

Our Ultraviolet Bandpass Clip-in Filter For Sigma FP/BF L-Mount opens the door to true ultraviolet reflective photography on full-spectrum converted Sigma mirrorless cameras (see compatibility below). By isolating the ultraviolet spectrum while blocking visible and infrared light, it reveals surface detail and material differences that simply do not appear under normal lighting.

This filter is especially well suited for applications like skin damage analysis, forensic work, astrophotography, and creative UV imaging.

While our original UV Bandpass Filter was built using absorption-based glass, this new version uses a precision interference coating design optimized specifically for ultraviolet imaging. This allows for significantly higher UV transmission, including stronger transmission at lower UV wavelengths where traditional UV filters rapidly lose efficiency. The result is approximately 3× more UV light transmission compared to our original absorption-based design, enabling faster shutter speeds, cleaner results, and improved performance when working in the ultraviolet spectrum.

The filter features a full width at half maximum (FWHM) range of 320–390nm and is centered at 355nm for strong ultraviolet isolation and balanced spectral performance. Its higher peak transmission allows more usable UV light to reach the sensor while maintaining excellent suppression of unwanted visible and infrared wavelengths. Average out-of-band rejection exceeds OD 3 (0.1%) from 420–1200nm, delivering minimal contamination and a clean ultraviolet signal.

Built with the professional-grade optics Kolari is known for, the filter is housed in a CNC-machined aluminum magnetic frame for a secure fit and maximum lens compatibility. It’s ideal for lenses without front filter threads and can be paired with external filters when needed.

Magnetic Mounting System – Quick and secure installation inside the camera body for effortless filter changes.

Professional-Grade Optics – Precision-crafted glass ensures minimal color shifts and maintains sharp, high-resolution imagery.

Ultra-Slim CNC-Machined Frame – A lightweight, durable aluminum design for a perfect fit without interfering with lens operation.

Premium Multi-Coatings – Anti-reflective, anti-smudge, hydrophobic, dust-resistant, and scratch-resistant coatings for superior durability.

Compatible with Multiple Lenses – Works with a wide range of lenses, ensuring flexibility across different shooting setups.

Our ultraviolet filters require a full-spectrum converted camera and will not produce the intended effects on stock, unmodified cameras.

Our Kolari Magnetic Clip-In Filters for Sigma FP/BF (L-Mount) are compatible with the following cameras:

Sigma FP
Sigma BF

Our Kolari Magnetic Mounting Plate for Sigma FP/BF L-Mount is required to use our clip-in filters with your camera. If you’d like to purchase additional plates, click here.

Not compatible with the following lenses:

Sirui 50mm f1.6 Anamorphic
TTArtisan 75mm f2
TTArtisan 40mm f2 Lens.

Getting started with UV photography may be tricky, but it doesn’t have to be. Here are a list of resources and articles to help you get started:

UV Photography Compatible Lenses

UV Photography Lighting Solutions

Shooting Video In Ultraviolet

What Makes A Good Ultraviolet Filter?

Solar Visions Project by Pierre-Louis Ferrer

If you have any questions regarding UV photography, feel free to reach out to us at contact@kolarivision.com and we’ll be more than happy to help!