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Anita, you can increase the step size and while doing so, your sampling in
Z is not meeting the Nyquist criterion for optimum resolution. You need to
break some rules, if you deviate anywhere from optimum. Although you break
this rule, if you meet the next rule that is, keeping your xy pixel size
approximately half or lower than half of whatever Z step you are willing to
use. This you can achieve by using (increasing) the digital zoom and this
will produce a reasonable image despite loss of some info in Z. If you are
not willing to alter the zoom you can increase the resolution but again at
the cost of time, so may not be useful.
For more information, you can download the program (30 day trial) Autoquant
or Autodeblurr from the website Aqi.com, which comes with a 200 page
wonderful manual in pdf format, which will give you ample straight forward
info on compromises you can/can't afford while sampling in two, three or
four dimensions.

Shiv
-No affiliation or commercial interest with the above mentioned companies-

Mayandi Sivaguru, Ph.D.,
Associate Director
Molecular Cytology Core Facility
Molecular Biology Program
2, Tucker Hall
University of Missouri
Columbia, MO 65211-7400
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Voice: 1-573-882-4895
Fax: 1-573-882-0123

www.biotech.missouri.edu/mcc/



At 08:47 AM 12/17/03 +0100, you wrote:
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Dear all,
>
>We are measuring the development of biofilms. The z-step is calculated
>according to the resolution of the lens. In first instance, we get only a
>few slices as the film is not so thick. But the film grows to more than 50
>micron and so we get a lot of slices with that resolution.The analysis of
>the stacks is going to take too much time.
>Can we reduce the amount of slices? What are criteria to do so?
>I hope you can give me some good thougts and ideas about this.
>
>Kind regards,
>
>Anita Wijnholds
>NIOO-CEME