Dear All, I am having a problem with a X60 1.4NA oil immersion objective which I am using in an Olympus IMT-2 inverted microscope. When I look at calibration beads (MP 0.17um yellow-green fluorescence - PS-Speck kit) they appear with a strange halo (I don't know how to call it) casting away from the beads (this in conventional observation) Something like: / / / O \ \ \ The lines are very weak, but noticeable. They display the same orientation disregarding the position of the bead in the field. When defocusing, the circular halos are not centred, but shifted in the same direction. It looks like it's a problem with the objective, because it's not noticed with other objectives, but this may be due to the lower power and brightness of these. It doesn't change with slide orientation or tilt. Now, when scanned (MRC 600), XZ sections are not perfectly vertical but slightly deviated (in the same direction in both upper and lower frames) Also, looking at the amplitudes of the FTs of the confocal images, these look fairly symmetric on XY but they are tilted on XZ planes. Older images (not beads but microtubules, which I would assume to also show the effect if present) do not show any deformation. Their FTs do not show any such tilt. Does anybody have any ideas of what can be happening? Thanks in advance Carlos