This gives the user a MUCH MORE ACCURATE indication of how sharp the image will be. Of course, if you're not comfortable with this diffraction business, you can simply disable that feature and instead use the app as a traditional depth of field calculator. You'll retain all the fabulous ease of use features! There's no need for long descriptions here — the app is free, so just play around with it. You'll find you'll never want to go back to the old ways of calculating depth of field. And if you like this version, wait till you try TrueDoF-Pro! Check it out, and its HUGE list of features, here on the App Store.