For the shot in my living room, the exposure was actually 4 seconds @f/16. It was hard for me to believe, too. You have me doubting myself now, so I'll check again tonight. I cant check right now because I took the picture of my couch at night, so there was no (or very little) light coming in through the windows.
I didnt adjust for reciprocity at all on the first one, and I kinda just guessed at reciprocity adjustment on the second shot I did outside.
I noticed that you adjusted for reciprocity by adding about two stops overexposure. Is that a rule of thumb kind of thing or is there an actual equation for adjusting for reciprocity? I've read the data sheet for hp5+ and found the recirpocity chart, but I dont think it covers exposures longer than 75 seconds. I dont have it printed out, but I'll look it up again and make sure about that
Reciprocity differs with emulsions, but the attached chart may serve as a guide. This is the reciprocity chart from Way Beyond Monochrome'. It is constructed from data, I received from Howard Bond, John Sexton and my own experiments. It has served me well so far.