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Scott,
I use one of the Edmund red filters with Tech
Pan. It really gives a nice contrast image of the NA nebula. It is
not narrow band, but I don't think it has to be to work for these types of
astrophotos. Most of the skyglow and light pollution is in the yellow to
green parts of the spectrum, below the 600 nm cutoff of this filter. I
found that exposure through the filter of a red nebula didn't attenuate the
image of the nebula noticeably. It just made the sky (the non-nebula)
really dark. The filter does affect focus slightly, so I checked the focus
in daylight with and without the filter, measuring the focus with a dial
vernier. It shifts about .010 to .012 inch on my FSQ106 (further out with
the filter).
The Edmund filter won't allow Sun pictures. I
can't think of a reason to need a narrow H-alpha filter for deep sky
photos.
Don
----- Original Message -----
Sent: Tuesday, January 14, 2003
03:42
Subject: [APML] 48 mm filter
Hey
list,
I’m looking for a 48 mm Ha filter
to fit my 35mm camera adapter. The adapter is made by Astro-Physics and
accepts 48mm filters.
I was looking at Edmund Optics. http://www.edmundoptics.com/IOD/DisplayProduct.cfm?productid=2079
I don’t think any of these will
work, but I wanted a second opinion. Any one with experience
with these filters?
Thanks,
Scott
Hammonds
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