Hi Tim, hi Natesh,

one expression is mathematically, the other one is technically 'more
> correct'.
> I favour the terms poor and good resolution to avoid confusion, or
> explicitly
> list the values.


just out of curiosity.. what's your definition of 'poor' and 'good'
resolutions? I suspect there are as many definitions as many subscribers to
this list are -;)

One way to quantify resolution is that what kind of detail you can see in
the map, like for example:

- deformation density (~0.7A and higher) = ultra-high, sub-atomic,
sub-Angstrom;
- H atoms (~0.9A and higher) = not sure what the name is;
- individual non-H atoms (~1.2A and higher) = atomic;
- hole in rings (~2A and higher?) = high;
- medium;
- still can see side chains (up to 4.5A);
- no side-chains but SS elements (such as tubes of density for helices) =
low
- no SS, molecular envelopes = very low.

Note, resolution alone is not a good measure though. Data completeness is
similarly important, e.g. a map corresponding to 2A resolution may look
like a 3ish A resolution if you miss some low-resolution data or
high-resolution end is severely incomplete (Acta Cryst. (2014). D70,
2593-2606).

Low resolution  --> worse than 2.7 A
> Ultra high resolution --> better than 0.95 A
>

Looking into this in some systematic way one can define low-resolution as
6A and lower, and ultra-high resolution as 0.7A and higher (Page 1291: Acta
Cryst. (2009). D65, 1283–1291).

All the best,
Pavel

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