The number 2 box brownie has a f18 105 focus length lens The size of the biggest aperture is between 7mm and 6mm diameter on the aperture plate
The f number = focal length /diameter of aperture
f16=105/6.5
f11 =105/9.5 which isnt the largest aperture on the drop down plate so f11, f16, f22 cant be correct where as f16, f22, f32 is
Unless anyone knows better