I'm looking forward to switch to digital MF (I'm on hassy with film now) and I'm a bit confused about circle of confusion, dof...
Let's speak about a 6 microns pixel digital back wich means a circle of confusion of about 10 microns. So we have at f8 (wich is the best opening usually regardons sharpness) an hyperfocal distance of ... 80m ! Wich means that in ordre to have sharpness to infinity an object has to be positionned at at least 40m... So everything closer than 40m won't be sharp. And also if one make fucus closerer than 80m there wońt be sharpness at infinite...
AM I wrong ?
No, you are correct for images that need uncompromized sharpness.
But why choisi ne a cof of 0.010 when human eye cańt do Moore than 30l/mm wich is a cof of 0.03 ?
That means that you can magnify the image from sensor size to something larger for viewing. BTW, human vision cannot resolve features as small as you suggest. Normal vision resolves features in the order of 10-16 pixels/mm (0.1 - 0.0625 mm), which means that you can magnify some 6 - 10 times, when you need that uncompromized sharpness (there will be no visible difference in sharpness between the focal plane and the edges of the DOF zone). However, sharpness doesn't suddenly stop at the edge of the hyperfocal distance, it gradually starts to fall off, and when you increase your viewing distance more than normal reading distance, nearer objects will also appear to remain sharp to our vision.
You should choose a CoC criterion, also based on the final viewing distance. When you view large format output from e.g. 4x the normal reading distance, you can also multiply your critical CoC of 0.010 to 0.040 mm.