I’m also interested in knowing how to do this. Increasing the resolution of the texture in the domelight ‘modify’ tab doesn’t really seem to make the sky more crisp in my images.
“Increasing resolution” of any image won’t give you better detail… You need to have a bitmap that is prepared in higher resolution, that’s all. For more “crisp” look you can try lowering/disabling blur parameter in your texture or disabling filtering in Corona’s devel tab.