I probably told that wrong, excuse the misunderstanding. I try....
It is 27 stitched shots. However for each single I took exposure brackets of 2s/4s/8s, hence 27x3=81.
Then I developed in packages of three, 1 shot 3 exposures in ACR. This shot I further processed in Photomatix with very subtle tonemapping settings.
After all 27 had been processed, I used photoshop and photomerge to allign and blend them together. (It is not perfect, but for a quick and dirty job allright)
Then I flattened the Layers and converted the remaining single one into a smart object. Then applied some further shadow highlight filter independantly to selected areas.
The way that works is that for example you choose the sky and draw a selection, refine the edge and then apply shadow/highlight as you see fit.
You will see that under this layer the smart filter has been applied and a mask was created. With that layer activated, hold down CRTL and press J to copy the layer including the smart filter. You'll see that the exact layer including smart filter has been copied.
Now go back to the original Layer and hold down CTRL and click once onto the filter mask beside the shadow highlight filter to select it. Then create a new layer mask with the little button on the bottom. You then created a layer mask from your filter mask.
Now go back to the copy of the Layer you just created and click onto the Filter mask. Press CTRL I and you inverted the selection, now everything but the sky is selected, and as you can see the seetings of the shadow highlight filter form the sky were applied to the rest as well.
But you do not want that, and because we have it as smart filter now, we can just open that S/H Filter and enter new values.
Pheww...
I then continued to add layers to several independant areas as described above. Stuff such as denoise, filters, etc. It got pretty big at the end.
Hope that all makes sense to you, I am pretty hopeless explaining stuff.