Quote:
Originally Posted by Peter Ward
Just had a search through my old email, while didn't find the correspondence, I'm fairly sure it was Alluxa.
P.S. found it. It was them $US895 a piece for <2nm, min batch of 10x 50mm
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I'm really surprised that they didn't have the foresight to just make a batch and sell them directly. I'm sure that they would become a coveted item.
Incidentally, the following article article for SPIE goes into the background of the technology behind the Alluxa filters. It is very informative.
http://spie.org/x105131.xml
One very illuminating graphics shows the passband shift (by virtue of incidence angle) for a range of focal ratios. It would seem that if you chose your centre frequency correctly (0.5nm towards the red end) the emission line will still be un-attenuated for the full aperture of optical systems down to F5 for a 0.94nm filter with a square wave transmission profile. At F4 however, it basically falls apart.
btw) Have you ever considered trying your (solar) blocking filter on an emission nebula?
It should by rights have a 1nm bandpass.
best
c
I do like the contrast and the framing.
