Quoting Jonathan Bishop <jonathan_bishop@sbcglobal.net>: > Hi, > > I am figuring an 8" f5 mirror. Can someone recommend the number of zones to > measure? I read Tex and he discusses using 4 zones, but that is for an 8" f8 > mirror (or was it f6). > > Since I am new to this probably 4 zones is easier, but will it be sufficient? > Start with 3 and then maybe 4. Hermit, holed up in Youngstown, Ohio