Ctf sensitivity
This presentation is the property of its rightful owner.
Sponsored Links
1 / 12

CTF sensitivity PowerPoint PPT Presentation


  • 58 Views
  • Uploaded on
  • Presentation posted in: General

CTF sensitivity. How do the errors in the estimation of the CTF affect the CTF shap itself and the final reconstruction? Which are the most important CTF parameters? How do the errors in one parameter affect other parameters?. Which CTF?. 1D CTF. 1D PSD. 2D PSD and CTF. Which CTF?.

Download Presentation

CTF sensitivity

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Ctf sensitivity

CTF sensitivity

  • How do the errors in the estimation of the CTF affect the CTF shap itself and the final reconstruction?

  • Which are the most important CTF parameters?

  • How do the errors in one parameter affect other parameters?


Which ctf

Which CTF?

1D CTF

1D PSD

2D PSD and CTF


Which ctf1

Which CTF?


Which ctf2

Which CTF?


How to measure the effect of errors

How to measure the effect of errors?

What happens to the ideal CTF if I change a little bit my current estimate of the CTF parameters?

What if I change a little bit only one parameter?

Can you express this as percentages?

Sensitivity=How sensitive is the CTF to the changes in this parameter

What is the average sensitivity?


So which is the effect of each parameter on the ctf psd and 1st zero of the ctf

So, which is the effect of each parameter on the CTF, PSD and 1st zero of the CTF?

The most important for the CTF: Microscope voltage, defoci, and chromatic aberration

The most important for the PSD: Background parameters, microscope voltage and defoci

The most important for the first zero: Microscope voltage, defoci, and fraction of scattered electrons


Which is the accuracy in the determination of the important parameters

<0.01% JEOL

Which is the accuracy in the determination of the important parameters?

These accuracies have been estimated by bootstrapping on the PSD values of a micrograph and reestimating for each subsample the CTF.


Do these errors affect the final reconstruction

Do these errors affect the final reconstruction?

In our experiments, it did not significantly affect the phase correction


Do these errors affect the final reconstruction1

Do these errors affect the final reconstruction?

Neither the amplitude correction


Can i remove the insensitive parameters

Can I remove the insensitive parameters?

Only the drift parameters, since in fact in these micrographs, there is no drift!!

The rest are insensitive (you can commit relatively large errors), but that does not mean you can remove them. If you remove them, then very bad CTFs are estimated


If i commit an error estimating one parameter how this affects the rest

If I commit an error estimating one parameter, how this affects the rest?

There are groups of parameters and changes in one parameter can be compensated by others. For instance, in the following table we see that changes in the major defocus are negatively correlated to changes in the scattered fraction and positively correlated to changes in the minor defocus.

These results have been achieved through the bootstrapping strayegy already described.


If i commit an error estimating one parameter how this affects the rest1

If I commit an error estimating one parameter, how this affects the rest?

This is to difficult for me to understand, can you further clarify who affects who?

Of course, through factor analysis we can discover groups of parameters strongly influencing each other

General background

Background medium freq.

Ideal CTF

Background low freq.

CTF decay due to incoherence

Background low freq.

CTF decay due to energy spread


  • Login