Howard Slavitt , Nov 10, 1999; 08:38 a.m.
Diffraction does not have a significant effect in large format until you reach about f22 (sharpest fstop without diffraction changes based on format). Also large format lenses are designed to be sharpest at about f22. If they were shot at f5.6 or f8, they would give much less desirable results. Also, the loss of sharpness due to diffraction is often overemphasized. It's an issue to be aware of, but if you need the depth of field you're much better off taking a diffraction tradeoff than having insufficient depth of field. If you're wondering about how large format can be so much sharper than 35 mm, it's because of image size