dear mapugers

I bought some time ago, when I still lived in the US, two MEADE 910B 2“ light pollution filters for
visual and photographic use. I was not satisfied with their performance, especially
photographically, so I tested the transmission of the filters with an calibrated Perkin-Elmer
Spectrometer I have in my lab. Both filters have transmission curves which are very different from
the specifications. Especially the filters have much reduced transmission for 656nm (H_alpha). one
has only about 33%, the other even less than 1%. These filters work not at all photographically and
give nearly no improvements visually. Compared with other filters I tested from fiends (orion for
example) the DO NOT work.

Does anybody have experience with the filters? Or has anybody else tested them in a spectrometer?
I sent my filters back to meade for replacement.

clear sky

joerg

ps: if somebody wants to see the transmission curve, i can send it to them
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-----------------------------------------------oOO-(_)-OOo-------
Joerg Schmiedmayer
Institut fuer Experimentalphysik
Universitaet Innsbruck
Technikerstrasse 25
A-6020 Innsbruck AUSTRIA
tel: ++43 - 512 - 507 6306
fax: ++43 - 512 - 507 2921
Internet: http://www.uibk.ac.at/qo
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