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. Author manuscript; available in PMC: 2009 Nov 17.
Published in final edited form as: Nat Protoc. 2008;3(6):977–990. doi: 10.1038/nprot.2008.62

Figure 2.

Figure 2

Micrograph selection. This is based on (a–c) CTFs and on (d–f) particle appearance. (a) A suitable CTF has several rotationally symmetric rings. CTFs should be discarded if they present drift, that is, (b) fading in a particular direction, or astigmatism, that is, (c) rotationally asymmetric. Furthermore, suitable micrographs should present a (d) homogenous population of well-separated particles. (e) Micrographs should be discarded if the particle density is too high, that is, the particles are so close to each other that they almost overlap, or (f) if the particles are very heterogeneous in size or appearance, indicating aggregation or other forms of particle instability. Panels d–f are on the same scale, and the scale bar in panel d represents 50 nm.