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Solar Spectrum
.2 Angstrom Advanced Solar Observer (ASO)
Hydrogen Alpha Filter
Designed as a rear telescope mounted
hydrogen-alpha filter, this filter's strengths are it's level of detail,
clear aperture and ability to heat and cool. Use of a telecentric lens
and energy rejection filter are required.
Visual
 At
.2 angstrom and 39mm clear aperture , this filter is unbeatable on a long focal length
refractor. Disk detail is extremely detailed and shows all
facets of the sun's chromosphere. Prominences are very bright
and show exceptional detail within them. Individual spicules can
be observed.
Warm up time is about 5
minutes. The time needed to change temperature is even less.
Imaging
Solar Spectrum filters
produce outstanding results photographically. Resolution
is limited by the telescope, camera and sky (not the filter). It can
handle almost any level of magnification.
Depending on the focal length
of the telescope, full disk or single area images can be taken.
Contrast between the lighter and darker phenomena can easily be
seen when focusing and in the final image.
Construction and Operation
The filter system consists of a filter housing
(above), Thermo-Electric Controller (below), converter and AC power cord.
The
TEC (above) is in a gold metallic housing that maintains a constant temperature
on the filter. The default temperature setting varies by filter.
On the filter housing, there is a small muffin fan mounted over a set of metal
fins. The fan/fin combination allows for cooling when the sun's energy
heats the filter beyond it's setting.
Different elements of the telescope can affect the temperature settings of the filter. Using a dialectic coated diagonal causes you to increase the
filter temperature. Also, the Baader "Cool" ERF will require a higher
temperature as well.
Adjustment is accomplished by pushing the SEL (select) button on the
control unit then holding the up or down arrows to the desired setting.
The setting moves rapidly. Moving the temperature 9 degrees C equates to a
.1 Å shift. It takes about 30 seconds for the filter to completely
change temperature. The OUT light tells you when the filter is cooling.
The OUT2 light illuminates when changing the temperature setting.
The
control unit plugs into the AC to DC converter and then into an AC power
source. You can also run the filter off of a 12VDC battery. A fully
charged 12VDC/7.2Ah battery lasts about 3 hours.
Summary
Whether in the eyepiece or
camera viewfinder Solar Spectrum filters consistently produce
quality views of the sun. Although technically more demanding
than most solar filters, this one is well worth the effort, time
and money you spend.
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