Thanks Todd for this explanation and sample images. I noticed that by enabling highlight reconstruction in filmic I was able to get a very pleasing blue sky with smooth transition. However, the white level set by auto tune levels needed to be adjusted towards the right manually to get the smooth blue sky. This exercise has given me some food for thought as I only ever thought about highlight reconstruction in terms of blown highlights until now.
Ya really I was just mucking about but I remember AP had mentioned something about using it to smooth transitions… At first I had just used Lum Y as that corrected that fringe but the sky was a bit lifeless so then I thought go back to the blue sky and then try to fix the fringe … so I used the HLR transition maxed out and tweaked those settings…that was not bad and I made a couple of brilliance tweaks to finish that off so the sky and foliage looked better and little to no fringe. What made it tough was the presence of that white fringe on leaves and some CA on the branches… correcting both was a balance … then I actually went back to just trying Lum y and the tone eq on the sky… this was simpler and corrected the fringe and left a nice blue sky…not too blue and not too washed out… typical DT many ways to skin a cat 
