Upload & Sell: On
f8 and be square, yeah yeah.
Ok, two disparate views on diffraction I want to put to you, both as it turns out by guys I respect here on FM Alt. 1. 'f22! you will blow away all the fine detail.', and 2. 'I use to a lot and know what the results are and like them.'
Too much has been written about it, it's very complex - airy disks, CoC, enlargement ratios, etc. Just see what you like, but from a viewing of a lot of RX1 shots last night, unless you're using macro and need much more dof than usual or need to focus very close and still need some good depth to the subject, even a typical subject focused at 3 metres allows plenty of front/back dof at f8/f11 and often even f5.6 for satisfying results.
Hyperfocal, my favourite guy is Harold Merklinger, and in general, I like his techniques, esp 'favour infinity' if far detail is needed and you have large objects near. Harold Merklinger is the author of: Ins and Outs of Focus (free pdf online).
But for focus, every image is different, which is why the subject has been controversial for so long, and why users just want a formula that works. Hyperfocal is not a panacea, more a crutch. Only the focal plane is truly sharp, and it gets more so with every sensor generation.