>>3263144FYI, that calculator has a minor updating bug. Look at the values for "pinhole diameter" and "optimal diameter". Reload the page, input your 180mm into Focal Length and click on "calculate". Then look over at "Optimal Diameter" and use that number to input the Pinhole Diameter and click on "calculate" again. Then input film size and ISO and calculate again. Then both sides will have correct numbers for optimal focal length and such. It is all wonky sometimes. I still don't think the exposure it lists is ever correct for photopaper, but time will tell once you have that pinhole size correct.
Here's the results I'm getting. Notice that in your image the pinhole diameter numbers don't match up.
