I have an AF Micro-Nikkor 200mm f/4D IF-ED lens, used on a d7100. Sometimes will only go to f4.2, sometimes to f4. otherwise seems perfect. User error, or something that needs fixing somehow, or not an issue if f4 vs f4.2 isn't a big deal- because it's not really. Seems to happen when the subject is very close to the lens, not an issue when a bit farther away.
Thanks for taking a look!