Re: [ccp4bb]: Re: Resolution (Bart's reply to the Rsym thread)

[Sue Roberts <suer@email.arizona.edu>]

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The actual resolution of a data set can be less than dmin, however dmin is
usually cited.

According to my old Stout & Jensen (p. 311 in the edition with the brown cover)

The ideal limit of resolution, that is, minimum separation at which two atoms
can be distinguished is 0.61 x dmin

and

In practice (with measurement errors, model errors, etc.), the real limit is
close to dmin which is usually cited as the resolution.

It seems to me that all 1.5 A datasets, for instance, are not equal. If I have a
crystal that really diffracts to 1.3 A and instrumental limitations prevent
collecting past 1.5 A, the maps, resolution of atoms, etc. look considerably
better than a more standard 1.5 A dataset and approach those seen for a 1.3 A
dataset. 


Sue

--------------------------
Sue Roberts
Dept. of Biochemistry & Molecular Biophysics,
University of Arizona
suer@u.arizona.edu (520) 621-8171