Main Designs of
Hydrogen Alpha Filters
Filters are mounted on telescopes
in two main ways. Either behind the telescope's focuser like
DayStar or Solar Spectrum filters (on the right) or like the front
mounted Lunt Solar Systems, Coronado, or SolarScope filters (left).
Which way is the best? Like
everything, it depends on your personal choice. Front mounted filters are easy to use, don't require electricity to heat and
are easy to adapt to a variety of telescopes but, don't usually offer super-narrow
bandwidths.
Some like to stack two filters together to drop the bandwidth down to
around .5Å.
Some rear mounted filters
offer extreme solar detail (down to .2Å)
and high magnification, but can be tricky to install (i.e. fitting extra hardware). While most
require electricity to operate
an oven at a high (but well-regulated) temperatures, some (like the DayStar
T-Scanner) do not.
Which one to buy?
The best way to find out which
filter is best for you is to determine how much you have to spend, narrow the field down to the best choices and go out and
look through them. Star parties, astronomy conventions and many clubs have Ha filters
on display at their events.
If that's not possible, use my number 1
rule of choosing a solar filter:
Determine how much you have to
spend and buy the largest aperture, lowest bandpass filter
you can afford.
Why Ha? |
The View |
What you see |
The Chromos |
Ha Emission |
Bandwidth |
Main Designs |
Ha Components |
Rear Filters |
The Etalon |
Front Filters |
Coronado filters |
DayStar Filters |
Solar Spectrum Filters
