Need to know more about your expts. Are you using arc lamp illumination? Light intensity delivered to the specimen can vary significantly and suddenly/periodically with old Hg lamps. We've speculated this is due to sudden and intermittent (approx every minute or so) shifts in the arc path. In any case, the problem goes away with installing a new lamp. I've seen problems with one high-end (cooled CCD, research grade) camera in which image intensity was reproducibly irregular. That is, at certain camera exposure settings (and not weird ones, at that), the distribution of exposure-to-exposure image intensities (determined for each exposure by averaging the pixel values in each color channel) was bimodal with peaks differing by up to 10%. A real headache to document, but the reproducibility according to exposure setting convinced me the problem is with the camera rather than the light source. If you need to distinguish intermittent (up/down) variations in light intensity from a sensor glitch, consider a colleague's suggestion to rig a way to run light from a battery-powered source through to your sensor. Depending on your set up, this might get a definite answer more easily than setting up power monitors, surge isolaters, etc. Robert L. Becker, Jr. Col, USAF, MC Department of Cellular Pathology Armed Forces Institute of Pathology Washington, DC 20306-6000 202-782-1573 On 6 Jun 2000, Maris Handley wrote: > > Hello Everyone, > > We are doing time lapse experiments with a Nikon microscope (using IPLab software). > When we play the movie back we are seeing large changes in light intensity (almost > random...not getting brighter continuously or dimmer continuously). Our exposure time > isn't being changed. I believe this is a problem with the light source stability, > but is there something else that might be causing this? Has anyone else seen this, > and what did you do to solve the problem? > > Thank you for any help, > Maris > > > Maris Handley > Dana-Farber Cancer Institute > Boston, MA 02115 > (617)632-3179 >
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