Re: [APML] Wtd: Ha 4x5 filter

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

Jim;
    Hydrogen Alpha filters are manufactured (?distributed?) by Lumicon - it
might be worth a call to them. Another option is Kodak Wratten 92 gel
filters. They are close to Ha filters in performance, I use them with my
Schmidt. They are available in sizes up to 6"x6", through larger photo
retailers. An RGB filter set is also available in Wratten, but with less
than optimum OIII response. Look for W25 (red) W58 (green) W47 (blue)

John Mirtle
Calgary, Ab. Canada
http://members.shaw.ca/jmirtle

----- Original Message -----
From: "cosmos" <cosmos@big.net.au>
To: "astro photo" <astro-photo@seds.org>
Sent: Tuesday, February 05, 2002 1:10 PM
Subject: [APML] Wtd: Ha 4x5 filter


> Hi..
>
> Can anyone in the group direct me to where I can  get a 4x5" Ha filter? or
> at least, a set of RGB filters.  My 225mm F4 astrograph is nearing
> completion and knowing what is available, we can redesign the vacuum film
> holder.
>
> TIA..
>
> Jim
>
>
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