Fig. 6.

Selection of diffraction length. As with X-ray crystallography, the diffraction length in electron diffraction influences the attainable results. The longer the length, the lower the recordable resolution is. (a–c) Electron diffraction patterns recorded from untilted aquaporin-0 2D crystals with 4,000 mm, 3,000 mm, and 1,750 mm diffraction length lenses, respectively. The attainable resolution is 10Å, 3Å, and 1.5Å, respectively, as indicated by the white circle. As the camera length changes the diffraction spots also spread apart or condense. In this particular example the 3,000 mm lens is the ideal one to use because these particular crystals do not appear to diffract significantly better than 3Å under these embedding conditions. Data are therefore lost in (a) and no additional data are gained in (c).