A great article here on how to do your OWN double star measurements and add to Science!!
http://www.skyandtelescope.com/obser...n-and-science/.
Why ? The reason for measuring binary/multiple stars is to determine the total mass of the double-star system. Why again you say ? Well this information is crucial for the astronomers working on stellar evolution!! And YOU can help!!
PS: Scopes in the 90mm plus range are good enough for this!!
bigjoe