Alexis thanks for your reply. I have had a chance to look through two of the 50ED Fieldscopes and both seemed very close. I did not have them side by side. I bought the second 50ED after looking through the one on loan. I liked the 50ED that much. I wish I could have two of these mounted like a binocular, a small Nikon 50mm Lowlander.:)
I have used the heli-coil type inserts to fix things and they work good if you are not taking apart the object a lot. The other style insert is more robust.