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Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
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I rarely shoot stopped down more than f11 - maybe f16 in a pinch. Most lenses today (and probably yesterday) suffer from diffraction when stopped down too much (which can cause loss of sharpness, IQ, etc). I find most of my lenses have a sweet spot around f8 as far as sharpness. Probably something you are all too well aware of.
www.bhphotovideo.com
Lens Diffraction: What It Is, and How to Avoid It
With the ever-increasing number of pixels manufacturers can cram onto a single digital image sensor, the optics themselves are beginning to become the limiting factor in image quality. This is making it all the more important to stop down our lenses in an effort to squeeze as much sharpness from...
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Yeah, it's all still a compromise. Short zoom range lenses seem to be less prone to the diffraction than the mega-millimeter ones like an 18~200mm. I find primes seem affected even less. A "sweet spot" at ∱8 is usually due to the fact you're using about half he diameter of the elements. That they're as sharp as they are across the f-stop range is an amazing thing.
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Yeah, that’s what I was thinking!...a giant dark star accriting surrounding matter?
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The lens diffraction is more an issue with sensors than film, methinks. Angle-of-incidence onto a sensor is different than onto a film emulsion. The sensor "layers" seem to be deeper than emulsion layers, producing an artifact or "bleed-over." From the "sounds" of it your R5 update may even negate the effect.