Rice grain on a CD ... ?? Details look quite good.
Darn it! I should have known that i can't hide anything for you guys. Indeed a rice grain on a CD, flash directly above. Reversed 35 F/2.0 on bellows (cheap *bay thing) on D810.
I was surprised by the lack of glare, since the flash head was almost directly aimed at the rear element of the lens.
Thanks Bjørn and Akira.