Exposure — Espenak t = f² / (ISO × 2^Q)
These are starting shutter speeds for each stage of the eclipse at the aperture and ISO you set above — set the shutter, shoot, then judge the result. Q is just a brightness number for the subject: each step of Q is one stop, and a bigger Q means a brighter subject and a faster shutter. The corona spans many stops at once, so no single value catches it all.
Corona spans a huge dynamic range — bracket wide (±3 stops or more around each value) and merge later. These are starting points, not answers.