Going from the other thread you basic problems are
a) you studio is too small for the work you are trying to do - move, rent a bigger one, take it out in the corridor, do it in your lounge etc
b) the lens you are using is crap and was never designed to be used on a D810 , add to that that shooting at 18mm because you are in a small space isn't a good idea.
c) your lighting set up is inadequate to the task at hand.
- i note that you are a junior member , can you clarify if you are actually a minor , or if its just down to your not having entered a DoB ? Also you say these are 'product photography' can you clarify who for - I'm presuming not Bolinger