Hi,
Yes. The effect of MTF is absorbed into the sharpening B factor to
some extent.
By the way, the MTF STAR file is defined in the detector
pixel size. When the reconstruction is down-sampled,
one has to re-scale the rlnResolutionInversePixel column
before using it in PostProcess. Otherwise, the MTF value is
under-estimated, leading to map over-sharpening. To compensate
for it, the estimated sharpening B factor tends to be smaller,
sometimes even negative (= blurring).
This nuisance will be fixed in RELION 3.1.
Best regards,
Takanori Nakane
On 2019/08/12 8:44, Matthew Belousoff wrote:
> To follow on from Gabriel's comment. We also don't see any difference
> with/ without MTF correction. The biggest effect to convoluting
> micrographs is the CTF and if this is sorted out properly, MTF effects
> seem to have minimal difference on final reconstruction due to the
> massive amount of averaging in SPA.
>
> On Sat, 10 Aug 2019, 8:40 AM Sara L Campbell, <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
> Dear all,
>
> The K2 MTF data I found out there seems inconsistent? Do folks have
> any thoughts or advice on this? Forgive me if I've made a rookie
> mistake :-)
>
> This MTF data is all for:
> _rlnResolutionInversePixel
> _rlnMtfValue
>
> (first one is same as the one in the RELION tutorial download)
> https://www3.mrc-lmb.cam.ac.uk/relion/index.php/K2-summit_at_300kV
> http://www.gatan.com/sites/default/files/MTF_Curves/mtf_k2_300kV.star
>
> (tried to search CCPEM to see if the question had been asked already
> + found the first file)
> http://www.lander-lab.com/downloads/mtf-k2-200kev.star
> http://www.gatan.com/sites/default/files/MTF_Curves/mtf_k2_200kV.star
>
> If I square the MRC*/300/ /keV/ *values, they come remarkably close
> to the Gatan */200 keV/ *values. Mysterious!
>
> Will the real MTF please stand up?
>
> Thanks for your help,
> -Sara
>
>
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