6924RE: [ccd-newastro] H-alpha filters
- Apr 1, 20021. Yes, this is normal. The Ha filter is a pretty thick sandwich, and cannot
be parfocal with thinner, simpler filters.
2. I occasionally can find a guide star, but I use a guidescope because it's
much more flexible with an Ha filter.
author of The New CCD Astronomy
From: remi lacasse [mailto:rmi.lacasse@...]
Sent: Monday, April 01, 2002 6:57 AM
To: ccd Newastro; SBIG user group
Subject: [ccd-newastro] H-alpha filters
A few months ago I received my H-alpha filter from SBIG.
It is the Standard type and I would like to ask 2 questions to
the group or to those who have used the same type filter before:
- I am using an ST-10E with the filter installed in the empty slot
of the CFW-8 but the focus point is very different from the
other filters. Is this normal?
- Is it possible to use (find) a guide star and if so what is the minimum
magnitude through the filter? Or will I need an external way to guide
when using the filter?
Thanks in advance
Rémi Lacasse et/ou Lise Charlebois
Lat. 46 deg.
Long. 74 deg.
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