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Subject: Monitoring light

Monitoring light

From: Martin Juergens <post<-a>
Date: Thursday, November 24, 2005
Helen Privett <hprivett [at] museum__vic__gov__au> writes

>...  Could anyone with recent
>experience (good and bad) in light monitoring equipment and strips
>please report?

At the House of Photography in Hamburg, Germany, we purchased an
Elsec 764c about a year ago, and I have since found all sorts of
uses for it. It measures lux, UV, temperature and RH levels, and can
log up to 10,000 values, which can then be downloaded by IR to a
computer for plotting as curves. Since we only recently installed a
fixed datalogger system for climate in the exhibition and storage
spaces, we have been using the Elsec to double-check on their
functionality. It can be set to log all four values at intervals of
10 seconds, 1, 10 and 60 minutes. We also use it to monitor light
and UV levels for exhibitions, and if the curator wonders if it
isn't getting a little too hot while the pictures are being unpacked
and hung, you just quickly check the device and impress him (it's
usually just his excitement at finally seeing the pictures on the

I have also used it to monitor the amount of daylight entering
through a window in the exhibition area, and could demonstrate the
dangers of days without clouds, where very large lux values were
measured. It thus also allows you to read the actual duration of
exposure to light, and I am sure there must be some way of
calculating the area under the curve (which would be the total
lux-hour amount), although the software (at least the cheaper,
simple version) does not allow for this. The only problem I have had
with this device so far has been that the software sporadically, and
for no apparent reason as far as I can see, doesn't react properly
and gives faulty values. In this case I have to re-download the data
from the device before I delete it by starting another series of
measurements. The software manufacturer has suggested it may be a
problem with my laptop, since he stated he has never heard of the
problem I have been having...

Also, as a practical tool for convincing sceptics about UV-glass for
frames, it is quite simple to use the Elsec to show the differences
in UV transmission between various glasses to curators and

In conclusion: this device gives you great flexibility and ease of
use while also allowing for datalogging over longer periods of time.
It's not a replacement for fixed sensors and dataloggers, but a
great addition to our set of tools. It is quite expensive, though.

Martin Juergens
Photograph Conservator
Beerenweg 6-8
22761 Hamburg, Germany
+49 40 2800 4785
Fax: +49 40 2805 6511

                  Conservation DistList Instance 19:28
                Distributed: Tuesday, November 29, 2005
                       Message Id: cdl-19-28-004
Received on Thursday, 24 November, 2005

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