I have a Symmar 135/5.6 that if you use the rear element only gives 235/12. So far so good. Then I notice that both elements have the same thread. So what happens if I take the front element and screw it into the rear of the shutter?
My guess is a focal length & f-stop range between the other two, but I don't have enough of the theory to know if that's correct or not. I really need a copy of Kingslake I fear...
I'll probably try it anyway just to see. Still, any ideas?