Hi, I am giving some demonstrations on photography to a 4th grade class (and learning much myself) and last week we took pictures to demonstrate depth of field. Using an F-5 with and 85mm 1.4 lense and 400 iso color film we took exposures using the aperture priority setting at 1.4 and 16. We used natural light coming through the window. The pictures taken at f.4 were very contrasty and the pictures taken at f16 had an even not so contrasty exposure. The pictures demonstrated depth of field very well, but I was surprised at the difference in exposure. Is this a characteristic of the film? I am assuming the very short exposure time had a lot to do with it. But I have never seen this show up so dramatically before. Thanks for taking the time to read this. And many thanks to whoever takes the time to explain it.