Posted by
Mark Cannell on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Precisely-driving-several-devices-from-IgorPro-through-National-Instruments-board-possible-tp4907273p4915172.html
Hi All
I must admit to being unimpressed by this 'improvement'. It removes
(from the researcher) the need to understand what a camera really does
and I doubt that it is accurate. Before someone howls at this, I would
point out that astronomers who routinely produce calibrated images use a
dark and a flat frame to achieve this. Without a dark, you cannot
calibrate the camera image -even if you assume it is flat (which it
isn't). The problem is that the camera changes it's properties
(especially the EM register) so no single calibration is going to be
accurate. Since it is easy to actually use darks and flats to calculate
actual photon numbers, why rely on a manufacturer calibration? I suggest
it's a bit like assuming your Gilson/Eppendorf is still correct and
everyone knows that's not GLP -right? But let's be clear, most people
don't give a damn about how many photoelectrons there are -they just
want a pretty image. For the few cases where photo-electron numbers are
needed, the time taken to take darks and flats are trivial compared to
the time taken in precise experiments.
my 2c
Mark Cannell
>
> *Van:* Confocal Microscopy List
> [mailto:
[hidden email]] *Namens *John Oreopoulos
> *Verzonden:* vrijdag 16 april 2010 16:04
> *Aan:*
[hidden email]
> *Onderwerp:* photons vs. photoelectrons?
>
> The recent release of the Photometrics EMCCD "eVolve" camera which has
> the ability to output images with pixel values that correspond to
> photoelectron counts (instead of arbitrary digital count units) has me
> wondering a bit something. The idea behind this camera, as I
> understand it, is that having images reported in terms of
> photoelectrons instead of counts (ie: an absolute scale vs a relative
> scale) will allow a better comparison of image data between labs
> around the world, and even for single user comparing images acquired
> with a particular microscope from day to day. Seems reasonable to me
> and sounds like a pretty good idea. What I'm confused about is that
> I've seen some papers in the literature, mainly those that deal with
> single-molecule studies, that report image data in terms of actual
> photons detected. Is there a difference, and more importantly, can
> someone explain to me the advantage of using photon counts vs.
> photoelectron counts?
>
> (No commercial interest for Photometrics)
>
>
> John Oreopoulos, BSc,
>
> PhD Candidate
>
> University of Toronto
>
> Institute For Biomaterials and Biomedical Engineering
>
> Centre For Studies in Molecular Imaging
>
>
>
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