The Ercona I was made after the war by the VEB Zeiss Ikon in what became the DDR. It has a Novar 11cm f/4.5 lens. Speeds are B, 25,50, and 100. My copy of it is very early and lacks the provision for a mask to shoot 6x6 rather than 6x9-- It has only the one red window on the back, in any case Mine has a very dimly impressed "Ercona" on the back leatherette, but otherwise is identical to slightly earlier production of the Ikonta C (521/2). I was so inspired by the recent spate of old folder shoots here, most recently today with Louis Meluso's Franka that I finally overcame my inertia enough to get out when there was some light on these darkening days.