Very interesting read Rowland. Thanks for posting.
Makes me wonder why the traditional Bhatinov mask design has been considered the go-to as opposed to a Y mask. The only reason I can come up with is that the multiple lines are intentionally used to dim the defraction lines so that only the brightest object comes through rather than a multitude of lines from surrounding dimmer stars ?
Certainly could be helpful in situations where it would be handy to focus close to the object but there are no bright stars close.
