I have just noticed that the pinhole exposure notes that came with the Bulldog were written for the 5x4 version. That raises a question, that, as your collective brains no doubt need exercising after the Christmas excesses, I shall put to you.
The optimum aperture / focal length is given as 125mm at f252 for the 5x4 format. So, my question is, does that hold for the 10x8 format, and if not, what should change? The aperture, or the focal length, or both.