Marumi M100 Magnetic Filter Holder: Setup and Filter Swaps

Fit the holder once, then swap filters by magnet

The Marumi M100 works differently from a traditional square filter holder. Instead of sliding a filter frame into a slot, you attach an aluminium magnetic holder to the front of your lens, then attach and remove filters by magnet. That makes it a good match for landscape work where you change ND strength or add a polariser between frames.

The holder ships with adapter rings for 72mm, 77mm and 82mm lens threads, so most full-frame zoom and prime lenses in that range can share the same holder. If your lens uses a different thread size, you will need a separate step-up or step-down ring, which is not included.

What the M100 includes

• Marumi 100mm Magnetic Filter Holder (M100): The M100 is supplied with adapter rings for 72mm, 77mm and 82mm lens sizes. Check your lens thread before buying; if it falls outside these three sizes, budget for an additional adapter ring.

  

• Marumi 100mm Magnetic Filter Holder (M100): The aluminium M100 holder attaches to the front of the lens and accepts magnetic filters. This is the core workflow: one holder stays on the lens while filters swap on and off magnetically.

Setting up the M100 on your lens

Work indoors or in a sheltered spot the first time so you can check the fit without dust or wind interfering.

1. Match the adapter ring to your lens thread: Pick the 72mm, 77mm or 82mm ring that matches your lens filter thread. Screw it on gently until snug; do not overtighten.
2. Attach the magnetic holder: Bring the aluminium holder to the adapter ring and let the magnets seat it. Check that it sits flat and does not wobble.
3. Test a filter swap before you leave: Attach and remove one filter a few times to feel the magnetic hold and confirm the filter seats evenly.
4. Check for vignetting at your widest focal length: The M100 is a 100mm system; on very wide lenses, stacked filters or thick rings can intrude at the corners. Shoot a test frame and inspect the edges.

How to change magnetic filters without moving the camera

The main advantage of a magnetic holder is speed. Once the holder is on the lens and the camera is locked on a tripod, you can pull a filter off and press another on without unscrewing anything. That reduces the risk of nudging the tripod between exposures.

Keep spare filters in a clean case and hold them by the edges. Before attaching a filter, check that both the filter and the holder face are free of dust; a trapped particle can scratch a coated filter or leave a mark in the frame.

Stacking filters in the M100: what to expect

You can stack filters in a magnetic holder, but each additional layer adds thickness and increases the chance of vignetting on wide lenses. A common landscape approach is to use a polariser as the base layer and add an ND filter on top, or to use a single stronger ND instead of two weaker ones.

The catalog does not list a maximum stack height for the M100, so treat stacking as something to test with your own lenses. If you see dark corners, remove one filter or switch to a thinner filter. Also remember that stacking a polariser with an ND filter reduces light further; adjust exposure after each change.

Magnetic holder vs screw-in filters

Both approaches work; the right choice depends on how often you change filters in the field.

• Magnetic holder (M100): One holder fits multiple lenses via adapter rings. Filters swap quickly and can be stacked. Adds bulk to the front of the lens and needs a holder plus rings.
• Screw-in filters: Compact and simple, with no holder to fit. But each filter must match the lens thread, and changing filters means unscrewing, which is slower and can disturb the camera.

Field tips for a 100mm filter holder workflow

• Keep adapter rings on your most-used lenses: Leaving a ring on each lens means you only carry the holder and filters, not a pouch of rings.
• Clean before you attach: Wipe the holder face and filter edges with a clean cloth; grit trapped by magnets can be hard to remove later.
• Recheck focus after adding an ND: A strong ND darkens the viewfinder and can affect autofocus; focus before attaching the filter or use manual focus.
• Store filters separately: Magnetic filters can attract metal dust; keep them in individual sleeves rather than loose in a bag.

Common questions about the M100

Can I use the M100 on a lens smaller than 72mm?

The supplied adapter rings cover 72mm, 77mm and 82mm. For smaller threads you would need a step-up ring, which is not included.

Does the holder rotate for a polariser?

The catalog does not state whether the M100 holder rotates. If polariser rotation matters to you, check the holder design before buying.

How many filters can I stack?

No maximum stack height is listed. Test with your own lenses and remove a filter if you see vignetting.

Product facts

• Marumi 100mm Magnetic Filter Holder (M100): Marumi 100mm Magnetic Filter Holder (M100) is priced at USD 68.30 in the catalog. A holder plus adapter rings can be more economical than buying separate screw-in filters for each lens size.