Heliopan’s premier 67mm 81A Filter allows you to control white balance issues and adjust color temperature on your image. Often times, an undesirable, bluish overcast can be seen via the camera lens during cloudy or open shade conditions. The 81A Filter enables the shooter to bring some warmth and tonality back to a much more acceptable level. Filter Factor: 1.2 (1/3 Stop). | Constructed from the highest German Schott Optics, which guarantees incredible optical resolution. Our glass is specially ground and polished to minimize internal reflections, while ensuring that the quality of your images are not degraded by using our optics in front of your lens. It is also specially hardened to resist most impacts. | Our standard 8-Layer Multi-Coating minimizes reflections and does not interfere with the resolution of your camera optics. | Heliopan’s precision cut brass ring ensures a secure and sturdy fit, are more resistant to side impacts, and less likely to bind or cross-thread after extended use. Also our newly introduced slim mount is made of black anodized brass stocks and feature limited rim length in front of the lens that they will not vignette with lenses as short at 21mm. | We do not source any materials outside of Germany in the assembly and construction of our products. All raw materials are prepared and hand-assembled in our factory and do not leave our facility until they are completely inspected by our quality technicians.