Hi The absence of clearly separate lunes on the first image indicates that the mosaic spread is rather high. If you increase the intensity threshold in spot finding you may be able to pick out spots belonging to a single lattice. If you increase the intensity threshold in autoindexing you may also be able to do this. My understanding is that HKL will let you do either or both, but of course I'd prefer you to do it in Mosflm ;-)
Looking at the higher resolution spots in the top left of the first image, it looks like you have three major crystals (at least) contributing to the diffraction - some of the spots are split into three close components - you may need to tune the spot finding parameters to either include all three components as one spot in each case, or perhaps just pick the strongest component. Because the spots are spread radially from the beam centre, I'd guess that the unit cell edges of the three components in that direction are a bit different. The second image indicates that you have a long axis almost aligned with the vertical (~80ยบ to the backstop shadow). The streaking together often happens if you've only got a few unit cells along that axis- actually not that unusual. Again, if you tune your spot-finding parameters carefully (small spot size, small separation between spots) you may be able to pick out individual spots and index successfully. I'd ask your assistant professor what he/she did to index successfully - he/she seems to know what he/she's doing! On 29 Nov 2010, at 17:14, chen c wrote: > I attached two diffraction images of my crystal, of which one seems normal as > protein crystal usually do, while the other one looks very strange ,with very > continuous lines on the image. > > In fact, of the 180 crystal images diffracted by my crystal, there is a > tendency between those two. > > I had thought that my crystal is a combination of many two-dimensional > crystals, between wich there are translational or rotational translocations, > namely resulting in a lack of translational symmetry in the third axes. As a > result of this, when I tried to index them using HKL2000, one of the cell > parameter is merely several angstroms. > > However, of the several data sets from different crystals, one data set is > sucessfully indexed by the assistant professor of my laboratory and currently > submitted to the operation of Molucular Replacement. > > This confused me a lot. Is what I thought wrong? Or is the very crystal that > was indexed a special one? > > Thanks all > > chen > <normal.jpg><more typical-1.jpg> Harry -- Dr Harry Powell, MRC Laboratory of Molecular Biology, MRC Centre, Hills Road, Cambridge, CB2 0QH
