Hi!
I'm fairly certain this is a bug as it never happened before the 1.6 release...
I can't get a noise-free result if I render an area snip within the Corona VFB. There's a strange border of a few pixels around the crop marker that does render correctly and then the rest inside is just left noisy. This, as I said earlier, did not use to be the case before.
I'm on Corona 1.6.1. Any ideas? It's quite annoying, especially when I need to do a patch render to fix an issue somewhere - the result barely resolves.
The issue is not present when rendering the full viewport.