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On the FV1000 the gain is applied after the A/D conversion. This becoms 
evident if the histogram is studied closely on images collected at gain 
settings higher than 1.0.  We confirmed this through dialogue with the 
local consultant and the manufacturer.
I understand that other makes have a gain stage prior to this step, as 
Mario suggests.

Regards,

Barry


At 05:16 a.m. 4/09/2008, you wrote:
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Ohkyung, James,
>
>I admittedly have never used an FV1000, but I am surprised that the HV 
>refers to current rather than PMT operating voltage (which drives the 
>current). Current generated in a PMT is exponentially sensitive to the 
>voltage applied and each tube will have an optimal voltage (usually 
>several hundred) that gives a linear current output over a range of light 
>intensities. Gain, on the other other hand, would be normally pertinent to 
>amplification of the PMT current output to something suitable for the A/D 
>converters that digitize the signal.
>
>A clarification would helpful. Thanks,
>
>Mario
>
>>Search the CONFOCAL archive at
>>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>>Hello Ohkyung,
>>The HV is the current supplied to the PMT.
>>The Gain is the amplification of the signal from the PMT.
>>hope this helps.
>>best
>>James Beals
>>[log in to unmask]
>>734.936-2051
>>
>>205 Zina Pitcher Place
>>2038 MBNI
>>Molecular and Behavioral Neuroscience Institute
>>University of Michigan
>>Ann Arbor, Mi
>>48109
>>
>>
>>
>>
>>
>>On Sep 3, 2008, at 11:28 AM, Ohkyung Kwon wrote:
>>
>>>Search the CONFOCAL archive at
>>>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>>
>>>Hello listers,
>>>
>>>I am wondering the difference between HV and gain in the operational 
>>>software of FV1000. Please educate me. Thanks very much in advance.
>>>
>>>Ohkyung
>
>
>--
>________________________________________________________________________________
>Mario M. Moronne, Ph.D.
>
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Dr Barry O'Brien
Dept of Biological Sciences,
University of Waikato
Private Bag 3105
HAMILTON
New Zealand

Fax 0064 7 838 4324
Phone 0064 7 838 4179