Tempered glass is a toughened form of glass used in car windows, shower doors, refrigerator trays, and mobile screen protectors—and now Breakthrough Photography are using it to create their new Dark CPL and X4 GND filters.
Both filters are made out of a special SCHOTT B270® optical glass that boasts many useful properties.
Unlike the CR-39 resin used in Singh-Ray and Lee filters, this tempered glass is resistant to scratches and, at least according to Breakthrough, it won’t break even when dropped on hard surfaces. It’s also better at accepting coatings, allowing Breakthrough to apply their MRC16 and nanotec coatings for reduced surface reflection and easier cleaning.
Finally, the hardened structure of these filters also prevents warping, an affliction traditional resin filters can develop over time, leading to distortion that is particularly noticeable when using wide-angle lenses.
Both filters are special for more than their glass though.
The X4 GND is allegedly the world’s sharpest and most color neutral, while the Dark CPL is a novelty in and of itself. A combined polarising and neutral density filter, this filter can be used instead of stacking two filters together, which can result in vignetting around 19mm on a full-frame sensor. The Dark CPL eliminates vignetting down to 16mm on that same sensor.
Both filters are currently part of an already extremely over-overfunded Kickstarter campaign that is set to expire on June 3rd, with filters shipping in August. Click here to learn more or pick up one or both for yourself. Each filter will set you back $150, a discount on the $160-$200 estimated retail price.