Guys, I just had to completely re-render a 20 second animation after a client change that only affected a small area - that I would have been able to region render (and comp in AE), had I not had the vignetting on with the default of 30. D'oh!.. As some of you may or may not know, vignetting and region render do not play well together. Until there is native region render in Octane engine, Juanjo can not do a cropped version of the full image's vignette. This is why rendering just a chunk of a render with vignetting on and pasting into PSD or AE yields undesirable results. They do not match. And it is quite easy to forget to turn off vignetting when setting up a new scene.
So this got me thinking: maybe it is time for a vote to have Vignetting default to zero. Yes, vignetting is wonderful, and makes images look that much nicer right out of the box, and PS/AE vignetting often produces banding in lower res images - making a vignette in Octane far superior... but because of the region render issue alone, I personally think it should be set at a default of zero for new Imager: Camera nodes...
So here is my vote for Vignetting Default Zero: Yea!
Please vote below.
Edit: It is very unlikely that I would make this boo boo again. I've learned my lesson twice now. I am just trying to help others from suffering the same fate - and needing to re-render full images (or, god forbid, full animations) because of region renders not jiving with originals.