Hello all,

First time posting here, but i need some advice.
I acquired this massive piece of plastic and glass for allmost nothing ( ~10$ ). The seller told me that it`s about 9-10cm diameter ( 3.5-3.9 in ). Perfect for my 5x7 homemade box-in-box paper-negative camera. ( Will post it when it`s done )



To my surprise this thing has a diameter of 14 cm ( 5.5 in ) and a focal length of about 380-420 mm ( 14-16.5 in ) resulting in a f2.8 aperture.

The question would be : is this usable with a negative that`s 5x7 ? ( the diameter is grater than the negative width ). I was hoping for a f4..something for portraits..
I could build a much larger box camera for this, as i can get paper as big as 20x24in but i`ll run into some other problems.

I also have a few enlarger lenses i plan on using : Eskofot ultragon 150 and 210 mm f/9, zeiss apo-germinar 240,360,450 mm f9. All have f-stops, and thredead mounts. This one has neither.