[ic-racer]

How would I contact print a transmission step-wedge to a negative using natural light, with accurate timing? And also, how important is it that I do this test using natural light? Ralph, in his book, seems to suggest that it is important.

This is how I do it, I put an 80A in there for daylight correction:


Other knowledgeable people (like PE) use an enlarger to make the contact exposure of the stepwedge on the film.

Unless you are testing for film speed, you don't need a precise exposure. You just need to get enough bands exposed to make a reasonable graph.