Having delivered many lectures on DIY cameras, one problem with pinhole cameras always rears it's ugly head. Someone in the audience will squint and say " I suppose that is a tree ?"  but when you show a sharper image the comment will be " If I had wanted something that sharp I would have gone to Zeiss".  Simple solution, provide f 75 and f 300 and let the photographer decide.  This 5 x 4 camera has selectable apertures controlled by  the small knob  on the lower right of the front panel. The shutter, as with all of my pinhole cameras, is manually opertaed. Not much call for a Compur Rapid at f 75 

 

diy cameras P8