Hi Chris!
About the flare, I meant both of them. The top one can be erased form the picture easily (if you do edit it out, you can take out the blue light form the crane as well). If you don't have a lens hood, you can use your hand/jacket/body or any other item to block the light.
As for aperture and sharpness, I should have looked it up for 18-135 before speaking. Since it is not a particularly sharp to begin with (I have a 18-135 too),
high f-stop number helps¹.
About artefacts, they appear, if converting to JPEG is done with low quality settings. But again, maybe the forum software compressed it to reduce file size. You can see the artefacts, if you zoom into windows.
Good luck!
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1. A bit about f-stops and sharpness. When closing down the aperture, it increases and decreases the sharpness at the same time. Sharpness drops because of diffraction and no lens manufacturer can solve it. But the higher the f-stop, the more it hides the imperfections of the lens (in the extreme case of pin-hole cameras, you don't need any optics at all, since you have a tiny aperture). Therefore, if you have a sharp lens, like
35mm F/2.4, the peak sharpness is at F/4, while the
18-135mm at 24mm overall sharpness peaks at F/8. For your lens at 18mm the centre sharpness is at maximum at F/5.6, but the corners still benefit form F/11. Since here the subject is a building, overall sharpness is a priority, so the choice to close it down is a good one, but maybe not down to F/22, if F/11 is enough.