The result of Patch CTF estimation (multi) is strange

I feel that both the picture and CTF estimation are strange. What may be the cause?

What do you see in the image that you think is strange?

My main question is: Like the red arrows and the red boxes, why are there ripples? Is it a normal phenomenon? Thank you!

Yes, this is normal. CTF aliasing. Try Takanori Nakane’s CTF calculator here and you will see how tweaking different parameters affects this phenomenon:

In your case it shouldn’t be anything to worry about too much, although looking at how your Thon rings are fading not so isotropically I would check how much motion you are observing over the course of an exposure.

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OK. Thank you very much! :handshake: