hi guys,

currently i am having the follow tools.
D90+sigma 8mm fisheye+NN4. : 6+sky+nadiar.
great quality.

I am wondering under what circumstance people choose R1.

On side note, i am consider to upgrade my gear to D800 full frame.
I understand using D800+sigma 8mm fisheye, i can do it in 4+nadiar.