Hi Hana,



At least my understanding is as follows (please anyone correct me if I’m wrong). 



With EER mode the camera reads out at its maximum frame rate therefore each frame has very little dose. In order to do motion correction properly, you then need to group a number of EER frames together into a frame group so that there is enough signal. The values I’ve seen are ~0.9e/A^2 total dose per frame group. Therefore you need to figure out how many of your EER frames need to be combined to achieve this dose. The easiest way to calculate it for me is to take the total dose of one micrograph (e/A^2) and the number of EER frames (given by epu/tomo5 or calculated from your exposure time and readout speed of your camera). Let’s say for example you have 3.5 e/A^2 total dose split into 171 EER frames in a micrograph. You can divide your total dose by your desired frame dose (3.5/0.9=3.88) and then divide your number of EER frames by this to get your number of EER frames to give your desired dose (171/3.88=43.97). In this case you would put the value 44 in relion/Warp for your EER fractionation or frame group. My experience is that this number should be somewhere around 40 if you used a reasonable dose rate on a Falcon 4 camera. Note that in Warp if your number of EER frames isn’t perfectly divisible by your frame group the remainder frames are lost, I’m not sure how these are handled in relion5. 



Hope this helps,

Gavin



> On 23. Apr 2024, at 14:05, Takanori Nakane <[log in to unmask]> wrote:

> 

> Hi,

> 

> What is your pixel size (A/px), flux (e/A2/sec), frame rate (Falcon 4 is

> probably 248 fps, Falcon 4i is 320 fps) and the exposure time (sec)?

> Then I will give you an example.

> 

> Best regards,

> 

> Takanori Nakane

> 

>> On 4/23/24 21:00, Hana Svachova wrote:

>> Dear All,

>> I am processing the data in EER format in Relion but not sure about the value for the EER fractionation field in the I/O in Motion Correction job in Relion.

>> We have 7000 EER files. I read the documentation here: https://relion.readthedocs.io/en/release-3.1/Reference/MovieCompression.html but still not clear about the value of EER fractionation.

>> Could you please, advise me about this step?

>> Kind regards,

>> Hana

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