I have to share this experience with you guys.
I recently picked-up a "used" Photo-Research PR-705 spectroradiometer.
It's reading on par, pretty much, with all my instruments - amazing. Such a
lucky find.
I'm developing a small application to drive the instrument through the
RS-232 port (yes, it's that old.). Works very well but I had to experiment
quite a bit with the TimeOut settings. The instrument is placed on my desk,
aimed at the wall to my left, which is lit by a cheap, fluorescent task
lamp. So, I debug, trace through my program, set breakpoints, everything is
going well. Until, I closed the lamp. At which time, I started to run into
TimeOut Exceptions in my application? It was clear that the TimeOuts were
caused by the instrument taking longer "Integration or Exposure time" on its
own, taking into consideration the source of light it was commanded to
measure. I "crashed" the instrument a few times until I switched to
HyperTerminal to make the measurements. And that's when I saw that it took a
whopping 4 minutes and 43 seconds for only 3.17 Cd/m2 x=0.2987 y=03222 (CCT
7402K).
Wow! I thought, something must be wrong?
I went back to my application and lengthened the TimeOut to 1,000,000
miliseconds! I did another measurement (the light must have changed during
the time I was figuring this out?). And this time, the instrument took a
staggering time of 7 minutes and 14 seconds!!! to measure only 0.937 Cd/m2!
I have no reason to doubt the "precision" of this instrument, at this time,
but, gee!, it's going to take its toll on calibration time when I get to use
it to measure progressively darker and darker monitor values, towards RGB =
0,0,0?
Best / Roger
