Most people have never seen one! A truly spectacular lens. Aplanat's are very stable at f8. Slightly nervous at f6! At f4.5 they will exhibit a subtle 'buzz'. That's why no one ever got faster than f6 with these . . . except Voigtlaender. Their portrait series at f4.5 is an amazing achievement. This is one of the New York Series where the Serial numbers aren't as helpful. This is a lot of money. Rarity and desirability combined. A #5 sold on the auction recently for $1599. A no. 6 like this did NOT sell at $2666. But it had offers and did not re-appear. Look carefully at the images made with one of these lenses at my web pages. Front light is perfect. Rear light has a couple of mentionable nicks / scratches. The pics show them pretty well. They DO NOT hinder performance one bit. There is NO flange with this. Arghhhh! Where do they end up. If you have a no. 7 Heliar, the flange from that will work. Aperture is perfect. $2155 includes shipping in USA. A bit more elsewhere.