Can someone tell me how well and with what ease you can read Byzantine (Koine) Greek if you master Classical Greek?
I'm interested in studying late antiquity and Byzantine history and although the University offers many interesting history topics in the area, it only offers Classical Greek langugage topics in the history Department, as well as Modern Greek in the language department. Nothing in between.
I've heard that Byzantine Greek can be as removed from Classical as it is from Modern, so I fear that my study of Classical Greek may not be that relevant. The language units -offered from beginner's to advanced level - are not mandatory - but as a future historian of late antiquity I feel I must be able to read Greek competently. I'm just sceptical that Classical Greek is a way to go.
Can you please give me some advice?

