Hi
I would be interested in the prespecitve of those more experienced
than I in using an MRC-600 set up for photon counting in an attempt
to quantitate fluorescense intensity.  Two images, inadvertantly
acquired from the same microscope field (apparently with different
gain settings, same number of frames averaged) gave intensities
that differed by about 50%. The problem arose because intensity of
seperate internal calibration cells for for thes images were very
similar, making differences uncorrectable.  This does not appear to
be a simple photobleaching problem.  Is there a more objective
way to set the scope for photon counting or should one expect this
much random noise from the data.
 
Thanks
Keith Crist