Hi What seems to work best for me is using a combination of parts between NN3 and NN5. In other words I am using the lower rail of the nn3 on my rd16 which is perfect size for my dslr setting with the upper rail of the NN5 which allow me to use longer focal lenght lenses that the NN3 stock. This way it is the most compact set up for me. Any concern about this set up?