I've been taking some pics with a pinhole camera I made, and since the exposures are long, have been trying to correct for reciprocity failure. I forgot to do so on the first few shots, and remembered on the final few. The interesting thing is, the shots where I extended the time for reciprocity failure are way overexposed - unusable basically. The ones shot with no adjustment are fine. Hmm. I'm using Ilford Delta 400 film and the chart that Ilford provides for RF.