Another thing to try would be focusing on something at infinity and minimum distance and see if Theres softness at either extreme. That will give you a starting point. Also, at f/1.8, I'd expect softness anyway. What's it like at say, f/2.8?
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Another thing to try would be focusing on something at infinity and minimum distance and see if Theres softness at either extreme. That will give you a starting point.
Also, at f/1.8, I'd expect softness anyway. What's it like at say, f/2.8?