I am thinking I may have to just try Jon's suggestion and follow the instructions in Simmons book. I keep getting confused.
Dan, I held the lens out at arms length, front of the lens facing me. I held a ruler in contact with the front filter ring. The entrance pupil at wide open aperture is 58mm, not the 44mm - 45mm you suggested.
Now, you divided into 250mm, but this lens is a 15" telephoto (381mm) with an infinity focus of 9.5" (241mm). Wouldn't I divide 58 into one of those numbers to arrive at the widest aperture for the lens in this shutter? Can you explain the use of 250, and why is the entrance pupil I am getting so much larger than the 44mm - 45mm that you said I should be getting, at wide open?
At indicated f/5.6, the entrance pupil is 42mm, f/8 is 29mm, f/11 is 22mm, f/16 is 14mm, f/22 is 11mm, f/32 is 8mm
Also, I measured the opening of both old and new apertures at wide open without the lens cells installed. The old is 44mm, the new is 43mm.
BTW Dan, the aperture this lens came out of was also non linear...if that matters.