Canon 10-18 is a very good lens, I use it with Metabones adapter. You can go even wider with a reducer. Has completely silent IS in the lens. My Olly 12-40 is a teeny but sharper in the very center, but 10mm looks very cool. If you don't have the adapter, it is not be worth buying both. Get something more expensive.
I own the Laowa (Venus Optics) 7.5mm f2.0. A little gem. And I mean little, literally.
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