You must like a ton of bokeh if you need or want f1.8. Even at f5.6, there's bokeh, just more of the dog is in focus.
You might be able to get less bokeh, if you back it up. You don't need a lens more then f2.8, f2.8 is the cheap Sigma lenses, well more then my used YI lens.
That should be f5.6, unless my memory failed, to lazy to import it in AfterShot Pro to see, my default image viewer doesn't say the aperture.