I'm not sure if this is the correct forum, but if it's not maybe a moderator can move it please? In the PDF version of the Lens Collectors Vade Mecum on page 72 is a discussion about the F2.9 / 8" lenses used on the Williamson F24 aerial cameras from WWII ( WW2 ). They state that while many companies made these lenses for Williamson, Dallmeyer were the only company to print their name on the lens barrels and that the Air Ministry number was 14A/7080. I have one of these lenses and the stamp is in the form of a "J H D" in white outlined ink letters, but .... the Air Ministry number is 14A/780 , not 7080 which is why I think that the Vade Mecum has a misprint. Just an FYI for anyone doing future research on the internet (seeing as APUG is going to be the repository for analog photography information). cheers eh?