[3dem] FFT question

[Garry P Morgan]

Thorsten,
thanks for the feedback…attached is an FFT using my other holder (F30_holder1).  definitely no cutoff like i see with the previous holder.
so i would tend to agree…it’s the holder and not the microscope or some external source of vibration.  i usually use the same clip ring in both holders all the time, but we are now in the process of testing spare clip rings.  the first one i tried had the same clipping of the FFT under cryo conditions; it did look much better when at room temp (see second image…holder2_room_temp).  it also appears that the clipping of the FFT is always in the same direction, which happens to coincide (roughly) with the tilt axis…i.e., ~10º off vertical.  could that be a clue as to what’s going on?
thanks again for the help.
Garry


holder 1:
[cid:bfa47808-e222-4367-898a-427f873d0952 at namprd03.prod.outlook.com]


holder 2, room temp:
[cid:7bf446c4-e622-4cef-9149-6e202c62c3da at namprd03.prod.outlook.com]
On Dec 29, 2017, at 1:23 PM, Thorsten Mielke <mielke at molgen.mpg.de<mailto:mielke at molgen.mpg.de>> wrote:

Hi,

if the effect shows up with one out of two cryo holders only (is the room temperature holder giving good FFTs?) , than most likely something is wrong with that holder. One reason might be that the clip ring does not clamp the grid properly. Do you always use the same clip ring with each holder? Did you check the that holder at room temperature? If OK at RT, something might be wrong with the thermal bridge between the dewar and the tip. Is the cut-off always in the same direction?

Best,

Thorsten




Am 29.12.2017 um 20:23 schrieb Garry P Morgan:
Hi,
we’re getting consistently clipped FFT’s on our TF30…the attached image is from a 50-frame, summed/aligned image of the carbon (of a cryo-grid). the drift numbers are reasonably low, there is no astigmatism.  just wondering if any of you can provide a possible explanation of this?  it definitely looks like drift or some sort of movement, right?  we have 2 Gatan 626 holders, and it seems to only be happening with one of the holders…has anyone encountered a problem like this associated with a holder?
thanks,
Garry

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--
*******************************************
Dr. Thorsten Mielke
- Head Microscopy and Cryo-Electron Microscopy Group -

Max Planck Institute for Molecular Genetics
Ihnestr. 63-73
D-14195 Berlin

Tel.: +49-(0)30 8413-1644
Fax: +49-(0)30 8413-1385
E-mail: mielke at molgen.mpg.de<mailto:mielke at molgen.mpg.de>

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