This is the nodal point for the wide angle lens mounted on the UR-E5 adapter at wide angle. The right line is the nodal point. The distance between the lines is 31mm. If you take off the wide angle lens, the nodal point measurement is 2mm back from the front of the UR-E5. Also the center tripod hole of the Nikon is where the 5000 camera case splits in half. You can see the split under the hot shoe. So from the split to the first red line on the right is 67mm.