Marumi M100 100mm Magnetic Filter Holder

It may not be the best-known filter manufacturer but Marumi has been in the optics industry for over 85 years. It produces a huge range of filters with screw-in, round magnetic, and square filter options. The company’s square and rectangular filters are produced in collaboration with H&Y and feature an H&Y frame that allows them to be mounted in the Marumi 100mm Magnetic Filter Holder (M100).

As well as the standard graduated neutral density (ND) filters, Marumi offers more exotic options like reversed graduated ND and center graduated ND filters which can be useful when photographing sunset or sunrise.

Marumi sells the 100mm Magnetic Filter Holder (M100) filter by itself, but the Circular Polariser for M100 is specifically designed for use with it and the holder, and its adapter has a dedicated section for it. Similarly, it needs filters that are in a frame and designed to mount by magnetic attraction. 

Specifications

Filter size: 100mm type filters

Mount: Screw-fit via adapter rings

Construction: Aluminum with magnets

Key features

Marumi supplies the 100mm Magnetic Filter Holder (M100) with 72mm, 77mm and 82mm adapter rings but the holder can be mounted on lenses with other filter threads via a step ring (not included). The adapter rings have a wide, smooth rim that enables them to be threaded easily onto a lens, and a slightly recessed knurled section that can rotate separately from the outer part.

Marumi’s Circular Polariser fits within the raised edge of an adapter ring. 

Because the Marumi holder uses magnets to hold square and rectangular filters, there are no guide rails or filter slots to thread the filters into. This means that the holder is slimmer than many others, but it can only be used with 100mm-type filters that are mounted in a frame that is subject to magnetic attraction. 

A cog in the bottom of the holder knits with the knurled rim of the Marumi adapter rings to enable the Circular Polariser to be rotated without touching the filter itself.

It’s good to see a light seal around the aperture in the Marumi 100mm Magnetic Filter Holder as this prevents light leaks during long exposures.

Everything comes in handy soft pouch.

Build and handling

Marumi (or possibly H&Y) makes the filter holder from aluminum and it has a fairly chunky main section that gives it a very solid feel overall.  

The filter holder is held on the adapter ring by two screw-down retainers, one on either side of the back of the retainer. These prove very tricky to use when the adapter ring is on the lens and instead it’s better to mount the adapter ring on the holder and then screw the whole thing onto the lens.

Once an adapter ring has been mounted on the holder, the polariser can be moved into position. Without an adapter ring, the polariser is too small to be held by the holder. Fitting the polariser reveals a little surprise, it isn’t magnetic. Fortunately, when its screwed into the correct position, the polariser is held pretty tightly, but it doesn’t always slip straight into the right place and it’s a bit fiddly. Consequently, it’s important to be very careful with the fit, especially if the lens is tipped forwards and no other filters are in use. If a square or rectangular filter is in use, it will keep the polariser in the holder even if it isn’t screwed in properly.

As I mentioned earlier, the holder is designed to be used with Marumi’s filters which feature a magnetic frame made by H&Y. These are pulled magnetically onto the holder and are held securely. The magnetic attraction is strong enough for up to 3 filters to be stacked together. 

Performance

The square filter-holding section of the Marumi 100mm Magnetic Filter Holder is only the depth of one filter, but you can stack one or two on top using the magnetic attraction to keep them in place. The magnets are strong, but it’s still fairly easy to push a filter up or down if you need to adjust the position of a graduation.

There’s a small screw in one side of the holder that can be tightened to prevent a filter from being moved up or down, but this only acts upon the first filter in the holder, but it keeps it in place well.

When the polarising filter is in position, the cog at the bottom of the holder makes it easy to rotate it into the correct position to give the desired level of polarisation. If there’s a graduated filter, this can be rotated by moving the whole holder on the adapter ring, and the polariser can be moved again to compensate if necessary.

Verdict

The Marumi 100mm Magnetic Filter Holder (M100) is robust and well made. Thanks to its use of magnets, it’s very easy to mount and adjust square and rectangular filters. However, I’d feel more confident using a polarising filter by itself if the Marumi Circular Polariser for M100 was magnetic. Its screw-fit design isn’t as easy to use as you’d like.

In addition, while the fixing mechanism enables the holder to be held very securely on a lens, it needs to be attached to the adapter ring before it is screwed onto the lens. This isn’t especially problematic unless you want to change between lenses with different filter thread sizes on a frequent basis when you’re out in the field. It would be quicker if each lens had its own adapter already mounted, but instead you have to put the different-sized adapters onto the holder before it can be mounted.

Read more: 

• Best filter holders
• Best ND grad filters
• Best polarizing filters
• Best neutral density (ND) filters
• Best variable ND filters
• Best lens protection filters
• Best light pollution filters
• Best close-up filters
• Camera filters explained