So medium format won't really help me in what I want but it will give me a nicer looking image ?
Hi,
Medium format will not help you with DOF, because you need to stop down further with their longer focal lengths. Different lenses may help, or not, it depends on how your current lenses render the objects. Tilt and shift capability will always be beneficial.
I do notice that the d800 doesn't give me good details in the highlights and unfortunately that is almost all jewelry.
Which Raw converter?
ACR/Lightroom compresses highlights in PV2012, unless you reduce the highlights slider control. Capture One by default uses a 'film curve' response, which compresses highlights. When you use a linear response you'll have the opportunity to make your own highlight roll-off with Curves and/or HDR Highlight control. Shorter focal lengths will help with DOF, but the shorter shooting distance also changes perspective and room to maneuver.
Will a tech can give me better ability to control dof ?
Maybe slightly more convenient but not really different compared to a good T/S lens. Shooting tethered helps a lot with such adjustments.
With proper deconvolution sharpening, you can restore a significant amount of diffraction blur. However, do not use apertures that will effectively limit your resolution beyond restoration capacity. If DOF is more important than resolution, you can also shoot from a little further away, a smaller magnification factor will add DOF at the expense of resolution.
Cheers,
Bart