<p>Hopefully, you have a loupe. I always do my focusing wide open and then stop down to the taking aperture especially for small product, still life, etc. and refocus. <br>
If you're not familiar, look up scheimpflug :</p>
<p>http://www.trenholm.org/hmmerk/index.html#SRpicR</p>
<p>Sinar used to have excellent books IIRC "Photo knowhow" that had explanations and exercises. One of the first guys I assisted had these and made me learn them (so I could teach him)<br>
DOF is less as the format size increases at the same given distance. <br>
Front tilt doesn't fix everything. <br>
You didn't specify the focal length, subject nature, etc. There are too many variables...</p>