Any idea what's going on here?

[75CentralPhotography]

Any idea what's going on here? I just started noticing some weird artifact on some of my photos, wherein the brightness and color is strangely-inconsistent across the sky. In the sample photos here: https://imgur.com/a/dwyz2Zy you can see that in the first one, the sky has a weird purple area in the middle and in the second one, there's a muddy blob in the sky and the edges are inconsistently colored. The third one is converted to B&W in Lightroom and the blues brought down to accentuate the issue in the image. These were shot on an a7rii. The first with the Tamron 28-75 and the second with the Tamron 17-28. Any ideas?

[dbmiller]

Looks to me like the lens shading compensation. Google will find many articles on it, here's one...

https://www.fredmiranda.com/forum/topic/1579842

[75CentralPhotography]

7 minutes ago, dbmiller said:

Looks to me like the lens shading compensation. Google will find many articles on it, here's one...

https://www.fredmiranda.com/forum/topic/1579842

Thanks...that might've been it. Just checked and it was turned on (though I don't remember turning it on). I've turned it off and will have to get out and test later this week. 

[dewarp]

Thanks for the heads-up on this one guys. Something to keep at the back of one's mind.

regards - Peter