Originally posted by EssJayEff Addendum (few months later): I was curious about this lens this morning so I searched eBay for Dallmeyer and turned up a "F2.9 PENTAC F=6" lens. Looking at the photographs for the listing, it is marked PENTAC on the lens.
Another addendum: I found a
webpage with more information re PENTAC lens that stated it was "designed by L. B. Booth for Dallmeyer and came to market in 1920. It is a 5 elements in three groups lens in the same design family as Voigtländer's Heliar. 8" Pentacs were made for the RAF during WWII by a number of lens plants. This particular lens was manufactured by the National Optical Company (N.O.C.) was a Taylor, Taylor, & Hobson daughter factory."
This seems to confirm that the 1933 and 1944 classified ads contained the same typographical error.