[Alt-photo] experience with UV light meters

John Isner john.isner at gmail.com
Tue Nov 13 15:55:50 UTC 2018

I just want to make sure everyone who read my earlier post about my
problems with the PPM-2 reads this:

The erratic intensity readings from the PPM-2 were caused by a faulty
4-foot extension cable.  After replacing the cable,  the PPM-2 behaved
properly.  I had to repeat all the tests I had done.  But at least I can
now rely on the results of those tests.    Thanks to Ian Parker of
lighmeasure.com for helping me diagnose the problem.

On Sat, Nov 10, 2018 at 3:35 PM John Isner <john.isner at gmail.com> wrote:

> Has anyone tried the Light Controller LC2 System from Ian Leake Studio
> <https://ianleake.com/light-controller-lc2-system/>?  If so, how do you
> like it compared with the PPM-2 meter, which seems to be somewhat popular
> on this listserv?  A big advantage of the LC2:  it has an optional power
> controller that can turn off the exposure unit when it reaches a specified
> dose, while the PPM-2 must be watched.  Of course you pay a lot extra for
> that power controller!  I assume both meters do an equally good job of
> measuring dose.
> The PPM-2 displays instantaneous intensity as well as total dose.  For the
> last two days, I have been testing my UV exposure unit with a borrowed
> PPM-2.  I initially thought a plot of Intensity vs. time would tell me
> something about my bulbs.  But I find the intensity display to be less
> useful than I had hoped.  The numbers move so erratically that it is hard
> to spot a trend.  If the PPM-2 displayed a 5-second moving average, it
> would be more useful.
> One conclusion I have reached, after running many tests with the PPM-2, is
> that my UV unit (fifteen  actinic fluorescent tubes, five electronic
> ballasts, all less than six months old) is behaving very erratically.  For
> ten minute exposures, even with a long preliminary warm-up, the dose can
> vary as much as 2/3 of a stop.  This tells me I MUST switch from time-based
> exposure to dose-based exposure.  The question is whether I should I go
> with the PPM-2 or the LC2 system.

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