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Joe Shope wrote:
>
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> A colleague of mine asked the difference between standard imaging
> systems and photometry systems. Can anyone give a concise answer of the
> differences between the two?
>
> Thanks,
> Joe Shope
>
> Joe Shope
> Confocal Technician
> Microscopy Facility
> Utah State University
> Logan, Utah
>
> (435) 797-0866
> (435) 797-1575 FAX
> [log in to unmask]

Joe,

I might just pick up on a point from Barbara's comments, and that
relates to the nature of the specimen. Size of the object to be measured
is very important, particulary when you deal with objects approaching
the limit of resolution (bacteria, platelets....). We have a Leica MPS
system as well as confocals, and found that altho the photometer had a
wonderful dynamic range and was great with tissue sections, for very
small well dispersed objects (the platelets) we could NEVER get accurate
reliable measurments - background was always a problem, swamping the
signal from the specimen. And this was when working in point detection
mode, with masking surrounding areas etc. Performing confocal
microscopy, as Barbara said, with very careful control over imaging
parameters was the only way we could get accurate data on a cell by cell
basis. The same would be true if you were measuring discrete specific
structures inside larger cells or tissues.  So, the sorts of data you
are seeking and  is an important consideration in the decision. Perhpas
this explains why there are now very few systems out there to strap onto
a microscope.


Ian.


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Dr Ian S. Harper, Director
Monash Micro Imaging
The Microscopy & Imaging Research Facility
Building 13C, Monash University,
Clayton, VIC 3800, Australia

Email: [log in to unmask]
Tel: +61 3 9905 5635;  Fax: +61 3 9905 2766
Mobile: 0408 314168

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