To obtain full sharpness from the sensor of the Nikon D800 / D800E, one must think in terms of the photosite size when depth of field is considered.
The D800 and D800E have 4.88-micron photosites, which means that to fully exploit the sharpness of the sensor, a 5-micron calculation for depth of field is in order. More than that, and resolving power rapidly falls below the sensor resolution. Which is inevitable for many photographs, but worth bearing in mind when one considers which portions of the subject really need to be sharpest.
The conventional 30-micron circle of confusion used for depth of field calculations is a blur circle 36 times larger than a 5-micron COC, or about 1-megapixel of detail. Which is not exactly 36.
Zeiss 15mm f/2.8 Distagon depth of field
As shown below for the Zeiss 15mm f/2.8 Distagon, observe that at f/8 with the lens focused at infinity, peak sharpness extends from 5.93 meters (19 feet) to infinity. And this is with a 15mm lens, an extreme wide angle! Thus dies the fable of “huge depth of field”.
The notion of the “hyperfocal distance” to balance depth of field is not something I have found to be useful. Rather, it is typically destructive to the intent of the photograph. It is better to give peak sharpness to the most important part of the subject, not to blindly set focus to some random intermediary point, which might not even have anything of interest, or might be thin-air.
The take-away here is simple: precise focus is needed to obtain full resolution from a 36-megapixel DSLR, even stopped down. Consider photographic intent, and focus appropriately, sacrificing sharpness for some portion of the subject in order to emphasize it elsewhere.
Note also that theoretical depth of field is often much less than reality, due to optical aberrations. The Zeiss 15/2.8 Distagon is one lens delivers most of what is promised by calculations.
See Making Sharp Images for much more on similar topics.
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