Hi, I used the method in the Renner book, the method developed by Bender. There is a scale ruler and a calabration set and then into the enlarger. This method works great! I conducted a camp with 9-11year olds and they drilled their own pinholes and then we measured them. The final results were astounding, clarity and sharpness were terrific. I must admit I was very skeptical and I checked the accuracy of the measurement devise with a Purchased Pinhole and it was only about .02mm +/- off. As other have addressed in this discussion your measurement does not have to be dead on, a little bit of mismeasurement is manageable Good luck, Karen Carter
__________________________________________________ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com
