Need help on electron microscopy?

Question

If you are using a film densitometer with a step size of 7um, what is the minium magnification that you could use so that 20 Å information is transferred within the Shannon-Nyquist information limit of the digitized micrograph? What magnification would you use if you want your sampling to be 3 x the critical sampling frequency?

I know that the Nyquist limit is : the sampling frequency must be greater than TWICE the highest frequency of the input signal in order to be able to reconstruct the original perfectly from the sampled version.

so I think I need to do some on the 20Å information, maybe times 2 or divided it by 2. Can anyone help me?

Answer 1

I couldn't follow this, sorry.