I am looking for recommendations for the Circle of Confusion value to use for calculating the Depth of Field with an IQ180 and various lenses. I know this is somewhat subjective, but it would be useful to see what others are using to determine where to focus. My typical print size is 22x30 with lenses ranging from 40mm to 150mm for Landscape type photos. I would like to use an iPhone App to determine near and far focus limits for a given aperture and focus distance. Also, for images with distant backgrounds, does using the hyperfocal distance produce acceptable results? If not, how do you approach those situations. Thanks for your help.