I have just used the Spyder LENSCAL target and ruler to check 2 brand new 105mm micros, on 2 new D800 bodies. My first attempt was a poor setup with, what seemed very bad results on one camera and lens, I ran out of adjustment at 20...still seemed out. Next day I set up the target with a studio light on a tripod and was more precise with angles and distances etc. Ended up with much more accurate pattern and brought one lens to 0.0 on most used F stops with a -2 adjustment. The second camera/lens came good at -3 AF fine tune. What started out like one good camera/lens match and a VERY poor second set. Actually was my fault in being sloppy. I am much relieved that both D800 and Lenses are very close out of the box. 2 of my other lenses were so close I didn't adjust at all. But I personally think that unless its for marco work or VERY precise commercial work.....its not going to make any visible difference.