Posted by
Stephen Cody-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Precisely-driving-several-devices-from-IgorPro-through-National-Instruments-board-possible-tp4907273p4929148.html
Dear List,
I just checked the Evolve web page again, it is not a "Dark
Calibration" but a light calibration. A shutter is closed, and an
internal light source in the camera activated to calibrate the EMCCD.
Below I've extracted the relevant text..... I have no commercial
affiliation with Photometrics.
From Photometrics Web page (This is from a commercial company, I have
no affiliation ad I have no personal experience of this product).
"EMCCD cameras are subject to aging of the EMCCD register as a result
of its usage. The Evolve has a simple calibration feature that
performs the industry’s most accurate EM calibration within 3 minutes.
A simple turn of the camera’s nose-piece closes a shutter and
activates a light source which the detector uses to calibrate its EM
gain. This ensures that users will receive the most accurate EM gain
and EM gain applied matches what the user requests.
Simple software control will allow the user to use this feature as a
manual shutter in order to block all light from the sensor in order to
take dark reference frames if necessary."
On 20 April 2010 09:37, Stephen Cody <
[hidden email]> wrote:
> Dear Mark et al,
>
> As I understand from the promotional material for this camera, there
> is a dark calibration procedure built into the camera. The eVolve web
> site while very glittzy is quite informative (if you can stand the
> hype)
>
> Stephen Cody
>
> On Saturday, April 17, 2010, Mark Cannell <
[hidden email]> wrote:
>> 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......
>
> --
> Stephen H. Cody
>
--
Stephen H. Cody