Hi. Nothing helped me check accuratly the 6" mirror's focal ratio... I tool of the Foucalt tester of list, the sun test doesn't work... HELP!!!!!! I can't build my telescope without knowing what's the focal length... - - - - - - - - - - - - - - - - - - Looking for a webmaster? E-mail me. Asaf Shtull-Trauring, asafs@ibm.net http://www.maxnm.com/asaf/ http://www.maxnm.com/asaf/nsc/