Great pics. You're way more advanced than I am.
I have some pretty good sunset pics too. But there all on slides and I haven't digitized them yet. And I still have my Olympus 28 mm lens that you mentioned.
Adapters are not expensive. The "better" ones seem to be an outfit called "Fotodiox" but there are cheapo chinezeo ones on Ebay for less. Once in awhile, one of them is a bit sloppy