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Dear Listmember,
        We have a user who wishes to image some archebacteria which grow in clusters up to 100 microns in diameter.  One question is:  do the cells and the spaces between them change in character and chemical composition from the outside to the inner parts of the cluster.  Thus we need to use an ion probe and take Z-series, but the problem is that the clusters are very "squishy" and any movement of the standard oil-immersion 60x lens on the coverslip causes the shape of even 15um diameter clusters (smaller than the coverslip-to-slide distance) to distort.  It appears that the rapid Z-step of the lens cause a pressure pulse in the fluid, and thus accurate 3D reconstruction is difficult.
        My question is, would a water immersion lens produce the same effects?  I've never used one and it is an expensive item to buy - the medium is a fairly concentrated salt solution so Olympus might not be too happy about a trial!  Also we may want to vary the medium, so can the effects of altered refractive index be compensated for? 
        Thanks, Ian.

---Dr. I.E.G.Morrison       [log in to unmask]
   Dept.Biological Sciences, University of Essex
   Wivenhoe Park, Colchester, Essex CO4 3SQ
---Tel: 01206-872246           Fax: 01206-872592---