Main Designs of
Hydrogen Alpha Filters
Filters are mounted on telescopes
in two main ways. Either behind the telescope's focuser like the Solar Spectrum filter on the left or like the front
mounted Coronado
60mm filter at right.
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 .3Å.
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 temperature, some (like the DayStar
T-Scanner) do not.
The amount of detail and contrast depends on the bandwidth of the filter
and not necessarily
where it is installed.
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.
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
