The main area where magnets are gaining grounds is in the realm of third-party filters. Freewell has been supplying such products for a while, and Kenko / Hoya has recently begun offering their Instant Action magnetic filters (not yet in the US, however). Both companies offer a full lineup, with circular polarizers (CPL), neutral density (ND) filters, protective filters and even variable neutral density (VND) options. In some cases, they also offer adapters to use existing filters with their system, or magnetic lens caps. So the question is: how does this compare to other VND filters in similar situations? To find out, I took all three sets of filters out to shoot a few test shots: the Freewell, the PolarPro, and the Moment. Rotating a CPL filter with the M2 system is a straightforward process. We’ve made it simple and intuitive to adjust the polarizer to achieve your desired effect. The Magnetic Filter System K2 comes in one size with different adapters to fit your specific front lens diameter. Magnetic Filter System K2 – Source: Freewell Pricing and availability

Videographers and filmmakers should also appreciate the diffusion mist base filter. The filter’s 1/8 strength is just enough to create the desired effect without being too obvious (as it can be with stronger, 1/4 strength mist filters). Some videographers using cameras with super sharp digital sensors could very well leave this “mist” filter in their base ring at all times. Pricing The ability to attach regular lens caps to either the lens adapter or a filter is quite useful, it lets the user attach whichever cap is desired. The magnetic link is strong enough to hold the lens cap and filter pair in place solidly. Bernard Dery | Light And Matter CPL at 20mm When I tested the PolarPro and Moment VND filters in the past, I found that neither of them were perfectly accurate in terms of their f-stop designations. Both filter brands promised 3 full f-stops (EVs) worth of density, but only provided 2 1/3rd stops. If you’re anything like me, numb hands are dumb hands and they can’t accomplish anything useful. Especially not threading on and off a filter in reasonable time. This magnetic filter system by Freewell has a serious advantage in this case. What Comes With The Freewell Magnetic Filter System? A polarizer is a great filter to help cut glare and enhance colours. By rotating the filter you are able to target different areas of glare in your frame. A polarizing filter is also extremely useful when shooting in an area with lots of highlight since it helps to get a more balanced exposure.Generally, a consistent color cast will disappear when you apply auto-white balance in camera or color correction in post. However, color casts may change the relationships between true white and colors similar to the cast and reduce contrast between them. Take this into consideration when shooting. J. Matthew Gore Conclusion and Recommendations A big issue with circular gradient filters is that users can’t adjust where the gradient is in the frame — it’s fixed. With the K2 Island Slot, users can adjust a filter’s height to change its effect on their photos and videos, and even rotate the entire assembly. The K2 also includes an integrated spirit level, or “gradienter tool,” to ensure level gradient filters.

One other advantage of the K&F Concept filters is that they are available for a wide range of diameters, starting at 49mm, as opposed to 67mm for some competitors. However, if you want to shoot with a VND filter, your first need to snap the VND base filter into the inner filter slot in the base ring on the lens. Then, you flip one of the VND filters so that the “VND” text on the ring is facing you, and snap that on top of the base ring on the lens. Other filters are only regular ND which means they have just a single function as a plain ND4,” a Freewell representative tells PetaPixel. “Other systems use a single piece for the glass filter which has already been available in the industry for decades. The only thing unique about other similar products is that they are magnetic. Freewell filters are the world’s first magnetic VND that have a “seven plus one” feature set. Absolutely no other filter system on the market exists with such functionality and versatility.” As explained earlier, both the 2-5 stop VND and 6-9 stop VND may be used as circular polarizers when flipped over (and the base ring filter is removed). Circular polarizers improve clarity, increase saturation, and bring highlights under control. They are frequently used in landscape photography to remove reflections and punch-up color and clarity, though they can of course be used when shooting video as well for a similar effect.Each of these filters do exactly as they are intended to do. They darken the image by 10 stops allowing for longer exposures in brighter conditions. Each filter has it’s own unique colour cast, like nearly all ND filters on the market.

The company also says the kit’s magnetic adhesion will keep the filters in the holder firmly affixed, which prevents vibrations while they still remain easy to remove and adjust. The metal knurling on the bezel along each ND level helps grip when turning to change values and allegedly improves the accuracy of stop setting. The company also claims that transitioning from one-stop value to another is smooth and gradual, and should give a reduced occurrence of “x-pattern overlaps” seen in other variable NDs. That being said, it’s near impossible to accidentally bump this filter off. The magnets are quite strong and definitely require a firm hold to come apart. Since this polarizer is magnetic, it’s perfect to rotate in either direction with no worries of the filter unscrewing. Taken with the Freewell Magnetic Circular Polarizer (CPL) The red circle shows where the above climbing photo was taken. In the tests I put each of these filters through I did not notice any significant differences in quality and sharpness. Rather than wasting your time talking about those two aspects, let’s focus on the areas that stood out; colour cast and ergonomics. K&F Concept’s lens adapters have two advantages. The first is that they are quite slim, measuring at only 2mm once installed. The second, and possibly most important, is that the adapter lets the user attach regular lens caps. These advantages mean they can remain permanently in place on a lens. These filters feel good to use. Yes, you need to be careful as with any type of photography filter, but you don’t have to worry as much as when you’d use all glass square / rectangular ones. They’re light but don’t feel hollow. Their magnetic capabilities make them really easy to swap around when you’re out in the field. No more unscrewing and fumbling with filter threads on location. Just set your base ring to your lens, and from then on, it’s just magnets doing their magic.

The ND32 did a good job of increasing contrast and clarity — especially in the trees and green foliage. The five-stop reduction in exposure also allowed the camera to shoot at a larger aperture. When five stops aren’t necessary, you may use the CPL from the 2-5 stop VND filter for similar results. User experience The main things to consider when looking at filters are: colour cast, quality, ergonomics and sharpness.

In addition to using the system as a CPL or VND filter, you can also replace the inner VND base filter with a “Mist” VND filter, which works just the same as the other VND filters but adds a “Glow Mist” effect, essentially a bit of diffusion that will smooth out your image a bit. I generally don’t like diffusion filters, so I didn’t test this heavily. The Only Problem

Using magnetic filters is, quite simply, a pleasure. It makes it so much faster to mount filters, swap them, change lenses, adjust to the scene. It’s hard to emphasize just how much magnetic filters make the photographer’s life easier. In particular, when a part of a group with non-photographers, every second spent fiddling with photo equipment can get bothersome for the whole group. Anything which can speed up the process is welcome. I took the Freewell Magnetic Polarizer Filter on a multi pitch adventure up the Stawamus Chief in Squamish, BC. I thought if I had no issues with it while dangling 2000ft above the ground, then there certainly would be no problems at ground level. Our approximate route. Maybe the most exposed filter review anyone has ever made? What’s The Point Of A Polarizer In Photography? Like the Freewell Magnetic ND filter, the polarizer also had a green hue to it; admittedly less noticeable than the 10 stop ND. Performance wise, it did exactly as it should. Cut glare, enhanced colour and balanced exposure with no loss in image quality.