A field flattener for Orion ED80 ?

[2020BC]

Has anyone experience of using a field flattener in an Orion ED80 for photography ?

I'm told the Williams Optics 0.8x reducer/flattener is the go. Does anyone know about this?

[acropolite]

I think Bert (avandonk) has done some work with field flatteners and ED80's. Might be worth searching for posts by Bert.