In 2022, I switched from the Kase K9 filter holder with 100mm square & retangular filters to magnetic filters. They are much easier to handle, with less chance of breakage and have excellent optical quality. Based on reviewers I trust and my own personal testing, I prefer the Kase brand, particularly Kase Wolverine 82mm magnetic filters. They are thin with a strong magnetic grip, and do not add a color cast or noticeably degrade the image quality. They are my ‘go-to’ filters for circular polarization (CPL) and neutral densities: ND8, ND64, ND1000. These four cover most of my filter needs. Since they are magnetic, they can be swapped or stacked quickly. I’ve added magnetic step-up adapters to all my lenses so I can use one set of 82mm filters, even on smaller lenses. I recently color-coded them using oil-based paint pens so they are easier to distinguish from one another when in the filter case.
Although the standard Kase Wolverine Pro magnetic filter set – CPL, ND8 (3-stop), ND64 (6-stop), ND1000 (10-stop) – can handle most situations. I wanted to add a ND16 (4-stop) & ND32 (5-stop) to my arsenal. Kase does not offer these in 82mm magnetic format. So I had to look to other manufacturers such as Freewell, ICE, Marumi/H&Y, and Neewer. Freewell’s filters are of similar quality and specs as Kase and priced similarly. I wanted to try some cheaper brands such as Kase Skyeye, Marumi/H&Y, & ICE but was concerned about their optical performance. Would cheaper filters result in noticeably poorer image quality?
In a non-scientific comparison, I setup my tripod-mounted Nikon Z7 in my backyard on a sunny windless day. The Nikkor 50mm Z f1.8 lens was manually focused and set at f8. The test board had two Reikan FoCal laser printed lens calibration charts plus four magazine pages, added for color and fine text. Once in place, the camera was stationary, set to a 2sec shutter delay, and only the filters were swapped. I took three images using each filter and selected the 2nd one for no particular reason. All three images looked identical.
This was done informally to satisfy my own curiousity and not done with blogging in mind (hence the scribbled post-its labels). I thought the results were interesting so here are the images. Hopefully, these resized jpgs from raw Nikon .nef files will show my results – virtually no loss of resolution using the cheaper filters, under these conditions. (I may have to post higher res images to download since these jpgs are not great if viewed over 500% but click on the images for larger jpgs.)
My initial conclusion is the ICE Magco Magnetic Filters are pretty good and a great bang-for-the-buck. The Kase Wolverine filters are definitely more premium in finish & thinness but so is their price. The Marumi brand is typically considered a premium Japanese brand as well. But I was surprised this set of Marumi magnetic filters were labeled H&Y/China. From this test, I do not think the Marumi were optically superior to the ICE Magco. At roughly the same price (on Amazon), I returned the Marumi 3-filter set and kept the ICE Magco 6-filter set.
The Kase SkyEye magnetic filters are Kase’s line of cheaper magnetic filters. Optically, I could not see any image quality degradation when viewing the raw 46 megapixel photos in Lightroom at high magnification. The build and optical quality of the Kase Skyeye was comparible to the ICE Magco set but cost more.
If you want the piece-of-mind of buying the best filters for your expensive lenses (or have that mentality), then buy the premium filter set. I will use my premium Kase filters but will not hesitate to use the other brands when appropriate.
Sidenotes: If, like me, you own in high-quality screw-on filters. Another option is to buy magnetic adapters that convert your screw-on filters to magnetic. They aren’t cheap (~$28) but are an easy way to convert your $$$ (B+W) filters. It’s an alternative to buying a new set of magnetic filters especially if you’ve got them ‘dialed-in’. Note: Kase make an adapter kit that is different than their adapter rings or magnetic step-up rings. Be sure it specifies it coverts screw-on filters to magnetic. Kase really needs to label this kit more distinctly.
I’ve always put high-quality (B+W, Hoya Pro-1) screw-on filters on my lenses to protect the front element. But lately, I only use filters for their effect(s) or for protection under adverse conditions (rain, surf, dust). The optics of the Nikon Z system are awesome and I do not want any unneccesary glass in the optical path. Having magnetic UV filters, even cheap ones, are perfect for allowing the quick removal of the lens protection before taking an image.
Having a filter on your lens can save it from catastrophic damage – the screw-on filter below saved my 14-30mm lens when the tripod fell over on an uneven river bank. A filter wrench was required to remove the filter but the lens was undamaged and works perfectly.
Disclaimer: this is not a scientific test like DXOmark.com would perform. It was done under normal picture taking conditions to satisfy my own curiousity. I thought the results were worth documenting. Please conduct your own test if you are curious & skeptical about cheaper filter optical quality.