Why Choose a Magnetic ND Filter System
Traditional screw-on or slot-in ND filters can be fiddly and slow to swap, especially when you need to change density quickly between shots. The Marumi Magnetic Filter System solves this with a slim aluminium holder that attaches to your lens once, letting you snap square ND filters on and off with strong magnets. No more threading or sliding – just one touch and the filter locks into place.
The system is designed to be more compact than a conventional slot-in holder and eliminates light leaks that can occur with traditional square filter frames. Because the holder stays on the lens, you can stack up to three filters for combined effects without needing separate rings for each lens size.
Setting Up the Magnetic Filter Holder
Before you start, check your lens diameter. Look for the symbol ɸ on your lens barrel – the number after it tells you the filter thread size. The Marumi Magnetic Filter Holder M100 fits that thread.
- Attach the aluminium holder: Screw the Marumi Magnetic Filter Holder M100 onto your lens just like a regular filter. It is thin and light, so it adds minimal bulk.
- Snap on the desired ND filter: Choose from nine densities – ND4 (0.6), ND8 (0.9), ND16 (1.2), ND32 (1.5), ND64 (1.8), ND1000 (3.0), ND500 (2.7), ND4000 (3.6) – and simply bring the filter close. The strong magnets grab it instantly.
- Swap or stack filters: To change density, pull off one filter and snap on another. To stack, add up to three filters on the same holder for stronger light reduction or creative layering.
Magnetic ND Filters at a Glance
- Magnetic Neutral Density (ND) Filters: The 100mm square glass is contained within a sturdy metal frame with knurled edges and a wide tab at the top, allowing for ease of grip without adding fingerprints to the filter. The knurled edges and tab make it easy to handle the filter even with cold or gloved hands, and the tab gives you a clean spot to hold without smudging the glass.
Magnetic Neutral Density (ND) Filters - Magnetic Neutral Density (ND) Filters: These quality Japanese-made optics have state-of-the-art coatings for anti-static, anti-scratch, low reflection and to repel water & oil. The coatings keep the filter clean longer, reduce flare in bright conditions, and make it easier to wipe off dust or water droplets between shots.
- Magnetic Neutral Density (ND) Filters: They maintain a neutral colour and suppress any infrared light casting. Neutral colour reproduction is critical for both long exposure and video work – you avoid colour shifts that are hard to correct in post.
Creative Use for Long Exposure Photography
Long exposure photography – smoothing water, blurring clouds, or removing people from a scene – requires a strong ND filter to cut enough light for shutter speeds of several seconds or more. With the magnetic system, you can start with an ND64 (1.8) for moderate blur and quickly swap to an ND1000 (3.0) or even stack two filters for extreme darkness.
Because the holder accepts up to three filters, you can combine, say, an ND64 and an ND8 to reach a total of 7.2 stops (ND256 equivalent) without needing a separate ultra-dark filter. The magnetic snap makes it practical to experiment with different densities on location without missing the light.
Using Magnetic ND Filters for Video
Video shooters often need to maintain a specific shutter speed (usually double the frame rate) even in bright sunlight. An ND filter lets you open the aperture for shallow depth of field or keep the shutter angle correct. The magnetic system is especially useful here because you can adjust density between takes in seconds – no need to remove the camera from the gimbal or tripod.
The anti-reflective coating helps maintain contrast and colour accuracy, which is important when you are matching shots or grading in post. And because the filter snaps on firmly, there is no risk of it vibrating loose during a take.
What the Magnetic System Does Not Replace
The Marumi Magnetic ND Filters are designed specifically for the M100 holder. They are not compatible with standard slot-in holders or screw-on adapters. If you already own a different filter system, you will need the M100 holder to use these filters.
Also, while the system is fast, it does not offer graduated ND options in the magnetic range – for split-density work (darkening a bright sky while keeping the foreground lighter), you would need a traditional graduated filter setup.
