Petzval lens with soft focus adjustment.
Early Dallmeyer B series petzval lenses have rack and pinion movements, soft focus adjustment by unscrewing rear lens. Later modification -rigid setting, soft focus control by turning lens barrel (Turn for soft focus).
|No||Diameter of glass elements||Focal Length||Format|
|Dallmeyer 1B||50mm (2″)||152mm||CdV|
|Dallmeyer 2B||70mm (2 3/4″)||210mm||CdV|
|Dallmeyer 3B||90mm (3 1/2″)||275mm||Cabinet|
|Dallmeyer 4B||115mm (4 1/2″)||430mm||81/2×61/2|