Editing TIFF file with an adjustment brush vs. Photoshop Layer

Question

I have some TIFF files I need to do some adjustments on. Mostly darkening the sky. Where the sky meets the foreground it is made up of tops of Spruce Trees.
My question is, can/should I use the adjustment brush in Lightroom to do this, or should I make a layer in Photoshop to do this?
I have found that when using the adjustment brush over the tops of Spruce trees, it is best to just paint over the whole thing, or else it will look artificial. Not sure if doing this in Photoshop would make my life easier? Any comments? Thanks.
Scott

Answer 1

A couple of comments: either a graduated filter or a brush-painted adjustment which paints across (for example) the horizon / tree / silhouette line of (say) a bright sky, will naturally (or, better to say, unnaturally) affect  the overlapped parts too, IF you use the "Exposure" slider to do this. In that case one would need to be reasonably precise and finicky about the masking, which IMO goes a little against the intention of these tools within LR..
However, if you use the new LR4 "Highlights" slider instead, the result is much less artificial-looking IMO - even if you have painted (or graduated) quite loosely to include some areas of darker buildings, trees, mountains etc. This is because rather than affecting the whole tone scale, only bright regions of the picture are affected by "Highlights". Conversely, only dark areas of the picture are affected by the "Shadows" adjustment, when you use that.
So in that context, one would only need to erase back out of the painted mask, any areas where this adjustment was noticeably unwanted - which is often, a better way to proceed than attempting to paint your adjustment postively up to a boundary. The effect of a smoothly graduated adjustment can be achieved by using a very large, very soft-feathered brush in the first place, rather than the Grad tool - with the advantage that unlike the grad tool, a smaller harder brush can then be used in Erase mode to cut out areas as required. Depending on the nature of the adjustment, this too can be done fairly loosely - or, with Auto mask turned on.
Auto mask can be a little blocky and harsh in the way it treats an edge, but this tends not to matter when you are erasing out, so much as when you are painting in.