Definitely needs to be stickied. I didn't know a luxmeter could be had for so cheap.
Is it important that no outside light (other than from the light being tested) enter the sphere? What if I get the baffle size wrong, is that a big deal?
Is it important that no outside light (other than from the light being tested) enter the sphere? What if I get the baffle size wrong, is that a big deal?
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Yes, the only light entering the sphere should be from the torch being tested, which is why I used stiff white cardstock with tight fitting hole that matches the head to cover the the sphere entrance.
Baffle size was trial and error for me. What I did was use a torch shining into the input port of the sphere and tried various sized baffles until I found the smallest one that would cast a perfect shadow over the luxmeter sensor. Then I confirmed it by using other torches with various beam patterns. I made good use of a FTT here.
> You forgot one more reason .. to impress your BLF buddies ... Very cool
You are a good Dad ...Now go out there and give that lil girl a set of new streamers for her bike and 2000lumen bike light that will make the neighbor kids cry .
I thought about a plastic ball but the papier mache solution is way better.
Measuring things is the only way to develop this stuff otherwise wrong conclusions are commons. Many people think that the difference between say, 250L and 300L is huge but actually is barely noticeable even side by side.
Brilliant idea match! That took more than a little creativity and artistic resources to produce. I'm seriously impressed how well it turned out. Your typical style transformation of common-->exquisite. Thanks for the clear write-up!
Frontpage'd and Sticky'd, I re-added one of your pics for the teaser pic, hope you don't mind. :)
It seems that your experiences with working with paper mache as a child were put to great use! Thanks for sharing! Is the size of the sphere going to be sufficient in preventing your light meter from maxing out with higher powered LED's (XM-L - SST90)?
Nice easy to follow write up. Great Job! Is there any differences to using a bigger sphere like an exercise ball(more distance between light and meter). different readings?
Very well done, match!
You might want to study this article that I mensioned in my own IS review.
What I mean is that if the sensor can "see" the "first strike" (that is the hot spot on the wall opposite the light input) then you will get problems measuring a "thrower" light against a "flooder". If you still have the plastic dome on the luxmeter then it will be sensitive to that "first strike" and the thrower light will give a number that is too high.
The remedy is to make the sensor less sensitive to "sideways" light by removing the dome and/or make a baffle hide the hotspot.