I shot a roll of Tri-x with a Pentax SF10, which automatically reads the DX code and sets the ISO. When I began shooting with it, I noticed that the meter was drastically overexposing the scene (1/60 or 1/125 at f/3.9 in mostly sunny conditions). I developed the roll, and the negatives were too dense as I had expected. According to the manual, the camera defaults to ISO 100 when it can't read the ISO. This was also the first time using b&w film, so maybe it needs to read the barcode information on color negs?