For more, see Breakthrough.Photography.
Breakthrough Photography has introduced a series of magnetic-mount filters. As per Graham Clark:
We have not formally launched them yet , but you and anyone else can access information about them at this direct link. We created them not as a replacement for circular filters but as a replacement for square filters.
Add the appropriate size screw-in mount (screw that into the filter threads on the lens), and the polarizer / filter snaps into place. A ring on the mount allows the filter to rotate (for polarization angle).
I’ve shot this filter in the field; the X4 CPOL color balance is excellent with a sophisticated 16-layer multicoating. I previously reviewed the Breakthrough Photography X3 polarizer in detail; the color neutrality has since been improved on the ND (neutral density filters).
The question of magnetic filters is an interesting one. It allows quick on off without any unscrewing of the filter (say to swap filters). On the other hand, the screw-in mount to which the filter itself magnetically latches onto, well, that mount precludes use of the lens hood. If there is a need for frequent switching of filters, then the magnetic system makes a lot of sense. If the filter just stays in place, then I’m not seeing the advantage.
The manufacturer claims are as follows (some claims for the ND filter), showing an unprecedented attention to details that matter in the field and for long term use:
- Worlds most color neutral ND filter [unclear if true of polarizer, but it seems so, based on field shooting].
- Worlds sharpest ND filter utilizing SCHOTT Superwhite B270® optical glass, an ultra clear crown glass.
- 8 layer of MRC coating applied to each side of filter (16 layers total) with high light transmission.
- MRC coating is harder than the glass itself.
- Thinner and lighter than most filters.
- Full threads on both sides, machined from brass accepts filters and lens caps in spite of its thinness [not on the magnetic version].
- Laser engraved markings including a serial number on each filter.
- Texture for non-slip grip on the filter ring [not on the magnetic version].
A filter has much reduced value value over time if its coating scratches easily, hence hard coatings are a huge plus for field work over time.
The “traction frame” really is a superb idea—your author has cracked the glass in several filters by dropping them onto rocks as they slipped from the hand. The excellent grip of the filter will reduce the odds of such mistakes. The brass used is also the best material to avoid binding issues.
In addition to being a small company responsive to customers, the filter is supplied in an excellent case and with a microfiber lens cleaning cloth.
Below, not shown is the sturdy high quality box the filter ships in—not just some crummy cardboard surround as with every other filter brand I’ve used. Note also the cutouts to allow extracting the filter, and the fact that it is recessed into the foam, hence no rattle when carrying, and without the hassle of another piece of foam above it.
Color rendition is excellent, as in this image from Canon 135mm f/4L TS-E Aperture Series: Ancient Orange Tree Trunk.