View Full Version : using camera exposure meter for measurements
02-25-2010, 03:38 PM
Okay, I am trying to measure the light frequencies output by a specific light bulb. I am measuring to see if there is a peak near 410-420 nm, and that intensity drops off going below 400 nm.
I have a Finepix S2000HD camera (fujifilm). Can I use its exposure meter to verify a peak frequency near 410-420 nm, or can the camera measure this low/accurately?
02-26-2010, 05:50 AM
Hi Jake, Welcome to the Zo. Things seem a tad slow at the moment. Be patient someone with more knowledge than I have will be a long to answer this question. It appears to be pretty technical.
02-26-2010, 12:06 PM
Interesting question... I am not aware of any light meter which allows you to measure intensity as a function of frequency. Using narrow-band cutoff filters allows you to sort of "back-into" the answer but these are esoteric and expensive. What are you trying to accomplish (not meant to be a smart-aleck question)? Interesting to me as a practicing metrologist of over 45 years!
Don't know if you can tie the metering system to a specific light source but if you were trying to take aquarium photos which were lighted by 420 nm light you could come close by putting a purple reflector in the tank and then measuring the luminescence with your light meter. Try to get the histogram as close to the middle of the graph as possible by adding more light tubes while keeping the F stop close to what is needed for across the tank exposure. You would then have to remove the reflector to allow the lower reflectance of the fish and coral to fluoresce without being overwhelmed by the reflector.
If you are trying to get photos of laser emissions of DVDs or security systems I would hate to hazard a guess as to how that could be done.
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