Re: [APML] H-A filters

["John C. Mirtle" <spampit@shaw.ca>]

----- Original Message ----- 
From: "Gene Horr" <genehorr@houston.rr.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
<- snip ->
> a better product with the more expensive filters.  Perhaps the Lumicon
> filter was designed primarily for visual use?  This would explain the
> larger bandpass.
>
> Gene Horr

Gene,
    I don't think it was designed as a visual filter. It was sold and
marketed as an astrophoto filter, for use with tech pan. If you look through
it at night, about all you can see is the moon, some planets and maybe a few
bright red stars. It was released many years ago, as a means of tidying up
chromatic problems with lenses and to provide better light pollution
penetration than the (then) current and popular Wratten 25 filters. It did
so very well, but Lumicon never progressed further with this filter. They
could also have brought out 3-10nm filters, or other specialty
astrophoto/CCD filters. I remember at the '92 TSP that they were planning an
airglow rejection filter. Something to allow shooting after an active aurora
display! Unfortunately, many things didn't happen after Jack left the
company. No doubt this is one of the reasons that they are under new
management.

John Mirtle
Calgary, Ab. Canada

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