Extend Your View. The Zacuto Z-Finder Extender Frame are used to adjust the focal point of the Z-Finder Pro and Jr. viewfinders, and are primarily designed for those who require reading glasses or farsighted shooters. The frames snap onto the Z-Finder and can be stacked as needed, until focus is achieved. In the case of the Pro series viewfinders, the frames function as further extensions to the diopter’s dial-in focus, while for the Z-Finder Jr. these are required to make any adjustment to the -2.75 focal point.