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Hi, 
I agree with Steve that the "Gain" on FV1000  should be left untouched (set 
to 1). And that is also what the Olympus specialist told me during the initial 
training on our system.  If I understand correctly, the Gain control just 
multiplies the digitized pixel intensity by the set number (e.g., 1.25). This can 
be  done during post-processing in image analysis software of your choice.    
Perhaps someone from Olympus could comment when using "gain" would be 
beneficial?

When the signal is weak and would require high HV (above ~ 750V on our 
system) leading to high noise,  I use lower HV and adjust the lookup table to 
make the image look brighter, or even better, switch to photon counting (in 
that case, you definitely have to tweak the LUT to see anything in the image).

Stan


Dr. Stanislav Vitha      
Microscopy and Imaging Center
Texas A&M University
BSBW 119
College Station, TX 77843-2257

http://microscopy.tamu.edu

On Thu, 4 Sep 2008 12:15:34 +1000, Stephen Cody 
<[log in to unmask]> wrote:

>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>G'day Ohkyung,
>
>I'm only new to the FV1000, so if others disagree please correct me. 
>
>HV refers to High Voltage and is the number of volts applied to the PMT.
>To add to your confusion this is sometimes also called "Gain" or "PMT
>Gain" by other manufacturers.
>
>As you and others have pointed out the FV1000 also has a "Gain"
>function, and this is an amplification of the PMT signal as previously
>pointed out.
>
>Generally speaking I think it is preferable to have this amplification
>gain switched off (ie. set to 1), and use only the HV to increase
>signal. I presume as the Amp. Gain feature is offered by Olympus, there
>must be situations where if the signal strength is low, and if
>increasing the HV further results in more noise (Lower signal/noise
>ratio (S/N) ), then using some Amplifier gain and a little less PMT HV
>may produce a better S/N ratio (ie. a less noisy image). I have not yet
>found that set of circumstances. Can anyone comment in what set of
>circumstances the Amp. Gain becomes useful?
>
>Cheers
>Steve   
>
>Stephen H. Cody
>Microscopy Manager
>Central Resource for Advanced Microscopy
>Ludwig Institute for Cancer Research
>PO Box 2008 Royal Melbourne Hospital
>Victoria,      3050
>Australia
>Tel: 61 3 9341 3155    Fax: 61 3 9341 3104
>email: [log in to unmask] 
>www.ludwig.edu.au/labs/confocal.html
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>-----Original Message-----
>From: Confocal Microscopy List [mailto:[log in to unmask]] 
On
>Behalf Of Barry O'Brien
>Sent: Thursday, 4 September 2008 8:07 AM
>To: [log in to unmask]
>Subject: Re: FV1000 : HV vs gain
>
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>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.
>>
>>[log in to unmask]
>>[log in to unmask]
>>[log in to unmask]
>
>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
>
>
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