The Coronado Personal Solar
Telescope is a ready to use, all in one, complete hydrogen alpha
(Ha) or calcium K (CaK) solar system. Handcrafted for precision,
this scope fulfills owner David Lunt's dream of an inexpensive, easy
to use solar telescope available to everyone.
Design
These gold and black scopes
are as aesthetically pleasing on the outside as they are to view
through on the inside. Each of the individual components are sturdy
and have a well crafted, solid feel to them. Knobs and movable
parts are durable. Even the packaging is very well made.
At f/10, the sun is viewed as
a round disk and tuning the tuning ring brings the Ha scope on
band. The eyepiece holder is fixed in place.
Ha Performance
The Ha PST gives very
acceptable views of all the solar phenomena available with a
hydrogen alpha filter.
Prominences are bright and
show a
separation between them when they are close to one another. The
blackness of space can be seen through the center of a large loop
prominence. Disk detail includes large
filaments (river like flows
of hot hydrogen gas) and
spicules (small short lived jets of
gas).
Active regions show up nicely
due to the contrast between the lighter and darker regions of solar
storms. Sunspots are easily visible and stand out distinctly
against the lighter surroundings.
Things to consider:
Most Ha PSTs exhibit a "sweet
spot" or area of best uniformity. This spot will appear to be
perfectly on band and look focused. The surrounding disk will have
less detail visible and look more like a traditional white light
view (just colored red). You may be required to move the telescope
around a bit to see the entire disk on band.
Stacking the PST enhances the
disk detail dramatically! Spicules, filaments and active regions
will seem darker and more detailed. Prominences will continue to amaze you. For an additional
~$800 investment you get a much more satisfying view of the sun.
Also, to bring a camera to
focus, you'll need to add the lens portion of a barlow to the
camera. Simply unscrew the lens and install it onto a C mount
adaptor. Digital cameras can be held up to an eyepiece for imaging.
Binoviewers will require a
special optical corrector to achieve focus. Denkmeier Optical make
one that performs wonderfully.
CaK Performance
The Chromospheric Network is a
joy to observe in this little scope. Sunspots show up wonderfully in
CaK light and rival the best a white light filter can offer. They
truly shine in this scope. The large super-granules have good
contrast between the lighter incandescent areas and the cooler
background. The 40mm CaK PST rivals the higher priced 70mm CaK
telescope from Coronado. Both have a 1.25" draw tube.
This scope can handle
magnification reasonably well. Some darkening does occur at the
higher settings. Imaging is the same as the Ha version.
CaK prominences can be
imaged using the PST. You will be required to push the gain
extremely high when using a video type camera. CCD cameras will need
a high dynamic range to capture their faintness. Security cameras
work well for this also.
Something to consider:
Because our eyes yellow as we
get older some observers will not be able to see the details in CaK.
The sun will appear as a round violet disk devoid of any details.
Don't let this dissuade you from trying though. It's worth the
effort if you can see it!
There is no need to purchase
expensive oculars for use with the sun. Simple Plossl designs at 50
degrees apparent FOV are well matched. A zoom eyepiece is the best
value. Several varieties of 8 to 24mm zooms are available on the new
and used markets.
Simulated FOV
Hydrogen-Alpha
.6A, 25mm eyepiece
Calcium K
The PST: Is it enough?
At $499 US the price can't be
beat but, here are other areas to contemplate:
Ha PST views are nice but will
seem miniaturized when compared to the SM40, 60 or 90 telescopes.
The details are there but will seem smaller against these scopes.
The Ha PST does not require the
scope to be returned to Coronado for stacking like the rest of the
SolarMax line.
For those trying to decide on
which filter to purchase for viewing the sun it's a good idea to:
Determine how much you
have to spend and buy the largest aperture, lowest
bandpass filter you can afford.
If it's $500, go with a single
1.0Ǻ Ha PST. If it's $1500 then stack it. If you've got $2500 the
.7Ǻ SM60 is the best all around Ha filter available. If you think you're
serious about the sun then a .5Ǻ stacked 60 or .5Ǻ SM90 is fantastic.
For just starters though, a simple PST is a sure bet.
Telescope Data
Bandwidth
of the Ha PST
1.0Ǻ to .6Ǻ (stacked)
Bandwidth
of the CaK PST
2.2Ǻ
Focal
Length
400mm, f/10
Magnification
16x (25mm eyepiece)
Exit Pupil
2.5mm
Resolution
4.1" *
Weight
3 lbs.
*Resolution = {(1.22 x Ha wavelength) / ERF diameter}
x 206265. Where resolution
is in Radians, Ha wavelength is .000656mm, ERF diameter is 90mm and
206265
is the number of arc seconds in one radian.
Stacking the PST enhances the
disk detail dramatically! Spicules, filaments and active regions
will seem darker and more detailed. Prominences will continue to amaze you. For an additional
~$800 investment you get a much more satisfying view of the sun.
