I am just setting up my NN3 MKII for the first time. I have a Nikon D300 with a Sigma 8mm 3.5. I have seen the recommended settings on your site, using the CP, which are a lower rail at 60 and the upper rail at 87. However, what do these markings relate to? I mean what part of the NN3 do I place against the rail markings at 60 and 87?

My guess is that for the lower rail setting of 60, you put the edge of the inside flared base of the vertical arm right on the 60mm mark. Is this correct?

For the upper rail setting, my best guess is that you place the white line on the bottom of the CP on the 87mm mark. Is this correct?

I appreciate your help.