> Do you have any reading recommendations? Not really. I remember using a table which gave you the optimum aperture for maximum sharpness, based on the distan

> Do you have any reading recommendations? Not really. I remember using a table which gave you the optimum aperture for maximum sharpness, based on the distance that the lens moved when focusing between the front and back of the subject. That kind of thing is only really useful for MF and larger, and I only used it for things like landscapes where sharper was always better. The problem with small formats is that it's hard to know how far the lens is moving, so you can't really use this technique. In the most general terms, opening your lens all the way gives you aberrations, closing it all the way gives you diffraction, so you'll typically shoot in the middle unless you have a reason to do otherwise. For a rule of thumb, take the apertures you use for 35mm and adjust them by the crop factor. So if you liked to shoot everything at f/8 with 35mm (a common choice), then lean towards f/5.6 with your 1.5x crop digital. Conversely, if you start lugging around a 6x7cm camera, you'll use f/16 as your default. Yes, for really small cameras, this means really big apertures. The iPhone 4S always shoots at f/2.4, for example.