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Subject: Microscopy


From: Ted Stanley <tedstan>
Date: Monday, March 27, 2000
Niccolo Caldararo <caldararo [at] aol__com> writes

>I am presently researching new microscopy instruments for our
>Anthropology/Archaeology laboratory at San Francisco State
>University.  I have looked at the OloTech devices displayed at the
>AIC meeting in St. Louis and WAAC in SF.  I was wondering if anyone
>has purchased one of these devices and if they would be willing to
>share their assessment of them with me.  I am especially interested
>in the Digiviewer, Portascope and Scope on a Rope devices.

I've had my DigiViewer since last September and I'm pleased with it
though it has its limitations.  Performance wise it is not practical
for certain applications.  For instance, its resolution is not that
sharp.  It has at 330 TV lines horizontal.  Better systems have
around 470 and up, which provide good sharp images. For that reason
one cannot not perform critical observations of materials such as
pigment samples, for instance.  I connected the DigiViewer to my
Olympus BH-2 polarized light microscope and found that the
resolution can not capture the extremely fine structural details of
specimens at various magnifications.  I have a standard CCD camera
that has  470 TV line resolution and a Sony monitor at 600
resolution.  The same images are shown sharper and have finer

The other limitation is the composite line output of the DigiViewer.
A Y/C or S-video output found in standard RBG CCD cameras provides
more accurate color capture when connected to another source such as
a high end computer or monitor. In all of these respects no CCD
system or monitor is going to be as good as observing the image
directly through the eyepieces or oculars of the microscope.

When the DigiViewer is connected to a low magnification stereo
microscope (up to 60x) then it is very good for routine observations
such as monitoring consolidation treatments or examining prints or
printing to identify a particular technique.  And of course, it's
excellent for training or consulting when collaboration is needed.
The tilt LCD screen must be observed more or less straight ahead to
get a good view of the image.  So that may be a little awkward when
several people of various heights are trying to view the screen at
the same time. In the end I find that I have to sometimes switch
cameras around my scopes for certain applications.

When considering the DigiViewer one should perhaps take into account
the points I've raised as well as making sure that it will fit your
particular scope(s) and being sure that one can work comfortably
with the very small monitor of DigiViewer as well.  It's a good buy
for the price.  I haven't had any problems with it breaking down
(yet).  There is another system similar to the DigiViewer that is
marketed by another company.  It has much better specs and features,
but costs about 5 times more.  I hope that helps.

Ted Stanley
Head, Special Collections Conservation Unit
and Paper Conservator
Preservation Office
Princeton University Library
One Washington Road
Princeton, NJ 08544-2098
Fax: 609-258-4105

                  Conservation DistList Instance 13:49
                 Distributed: Thursday, March 30, 2000
                       Message Id: cdl-13-49-007
Received on Monday, 27 March, 2000

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