Is the specimen crystalline or amorphous? What are the crystallographic characteristics of the specimen? Is the specimen made of single crystals? What is the orientation of the specimen or of individual grains with respect to the

electron beam?

If you are interested in answer above question, use SAD or CBED. A diffraction pattern of the crystal lattice gives us information on the periodicities of the lattice. No single analytical technique can solve all of your problems. Each technique has its particular advantage. CBED provides more quantitative, precise and local information on crystals than the SAD. CBED is a technique widely used for determination of structure, symmetry details and atom positions in a crystal as small as 20Å in size.