 |
 |
Dear ccp4bb users, I have a question that concerns a problem with data collection (not directly related to CCP4). It might be a really stupid mistake I'm making... I'm attaching a diffraction frame where, as you can easily see, there is an annoying shadow (on purpose the contrast on the image has been forced to highlight the problem). The shadow doesn't correspond to the cryo nozzle, since the nozzle is set coming in from the same direction as the attachment of the beamstop, i.e. right opposite to the shadow. The detector is an image plate (Mar345), and this problem appears when collecting at high-ish resolution (say better than 1.8). I wonder if someone has encountered a similar problem...I've been playing around for a while now, unfortunately not finding a way out. could it be associated to the metallic pin of the cryo-loop on which the xtal is actually mounted? I thought if the loop is rather short, at high diffraction angles this could actually be a shadow generated by the tip of the metallic rod....they're pretty much conventional pins though, and I didn't step into this type of problem before. In any case how could I handle this, if it were the actual cause of this anomaly? I tried to adjust the collimator end, or even change it trying other sizes as well, with no success. I'll certainly appreciate any help / suggestions! Best regards, -- Alejandro Buschiazzo, PhD Research Scientist Laboratory of Structural Biology Pasteur Institute of Montevideo Mataojo 2020 Montevideo 11400 URUGUAY Phone: +5982 5220910 int. 120 Fax: +5982 5220910 int. 111