Zero Drawing

I attend drawing class once or twice a week and this year I've also been using pinhole cameras to take photos of various aspects of the area. Generally I leave it in some part of the room for an hour or so while I'm drawing. Above is a test of a recent idea - to use the pinhole to document myself at work. This is about a 20 minute exposure. The paper looks blank because I was having an off day and barely made any marks during the 20 mins. When I return to this idea I will make bold, dark marks quite quickly with something like charcoal or pen and ink to make the drawing more apparent. Really just a test shot, but promising.
Reciprocity is interesting in relation to pinhole. It's hard to find accurate data for most films so I have found that I need to test and make notes. I think me Sekonic told me the exposure should be 1 minute at f/128 and from experience i estimated I should do 20 minutes.