I just put together a 35mm pinhole camera (The Populist). I dont plan to make a habit of buying drug store film, but I was trying to minimize my losses in case my experiment fell apart. So my first roll to take through this camera is CVS 400 speed film, and Im trying to get a feel for exposure times. I downloaded a small app that gives me exposure times for most name brand film (Kodak, Ilford, etc.). You pick the film and it gives you a table. Basically Im just trying to get a feel for what brand or type of film the CVS film might be most comparable to in terms of exposure time. Can anyone help? Thanks. Brian By the way, my focal length is about 23mm and my pinhole diameter about 0.22mm for an effective f-stop in the neighborhood of f/105.