I have what might be the oldest dagor in the country. I have a gorgeous 16 1/2". Check out what is engraved on the outer rim. I'll try to type it exactly.................................................. GOERZ.... DOUBLE - ANASTIGMAT...... U. S. PAT. No.. 528155 SERIES III.... No. 7A ...... F. O. C. 16 1/2 IN. ..... No. 120XXX. ...........according to the serial numbers this was made somewhere between 1902 - 1903. Does anyone have any info on these really old lenes I would appreciate any help. ( where's andrew when you need him?)...thanks in advance