Personal Solar Telescope, 1.6" F/10 refractor with built-in <1.0 Ångstrom H-alpha filter

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The Coronado Personal Solar Telescope represents an economical new approach to serious solar viewing. The PST shows you much more of the living Sun than an ordinary glass or Mylar white light solar filter that shows only sunspots. For no more than the cost of a single premium eyepiece, the PST reveals the ever-changing tapestry of prominences leaping off the edges of the solar disk and the explosive upheavals of flares and filaments on the face of the Sun. All of this is visible in addition to sunspots in exquisite detail.

The PST consists of a 400mm focal length 40mm aperture f/10 refractor with an integrated hydrogen alpha solar filter using a full aperture energy rejection filter and a 20mm clear aperture internal etalon. The scope’s achromatic doublet objective lens is fully multicoated. The filter has a <1.0 Ångstrom passband, centered on the 6562.8 Ångstrom H-Alpha line. The passband width gives balanced views of prominences and surface detail alike. The filter is thermally stable, so there is no drifting off the H-Alpha line as the filter heats up during use. The 5mm clear aperture of the blocking filter portion of H-alpha system (built into the diagonal housing) is ideally matched to the focal length of the telescope to give full disk views of the Sun.

The scope uses proprietary internal optical focusing (operated by the external focusing knob shown in the product feature image). The scope and focuser are a completely integrated unit, with no external moving or extending parts (focuser drawtubes, etc.) to gather dust or grit during windy daytime observing sessions. A rotary collar on the optical tube allows you to fine-tune the filter etalon for the sharpest and highest contrast image. Do not confuse this collar with the focusing knob on the rear of the right angle filter housing. The fine-tuning collar has a limited range of motion and can be damaged if you try to force it to turn in a vain attempt to focus the scope. A thread-in metal lens cover protects the objective lens of the PST.

You can use most 1.25” eyepieces with the PST. To get you started observing, a 20mm (20x) 1.25” Kellner comes as standard equipment. While optically acceptable, most observers eventually will want to replace this economy eyepiece with one of better quality. Either a 12mm (33x), 18mm (22x), or 25mm (16x) Coronado CEMAX eyepiece would be an excellent choice for observing, as they are optimized for high contrast solar viewing of subtle prominence and surface detail.

The PST includes an internal modified Coronado Sol Ranger Sun Finder to make it easy to center the Sun’s image in the eyepiece. You can see the Sol Ranger screen in the product feature image. An optional hard case is available to carry and store the PST. The case uses the snug-fitting die-cut foam that the PST ships in to hold the PST securely. A 1/4”-20 thread tripod adapter socket is built into the base of the filter/diagonal housing of the PST to allow mounting the 15” long x 2.1” wide x 3” high telescope on a photo tripod. You can also install the lightweight (3 lb) scope onto a piggyback camera adapter that’s mounted on a larger scope for motorized tracking.

Each PST has a “sweet spot” in its field of view where subtle prominences pop into clearer view and the larger prominences show more contrast and detail. Experimentally moving the telescope around so that the Sun’s limb and prominences move to different parts of the field will soon reveal where your particular scope’s “sweet spot” is located.

An often-asked question concerns the difference between the economical PST and the SolarMax 40 solar scope at better than three times the price. The most obvious differences are in the filter bandwidth and the clear aperture of the blocking filter. The SolarMax 40 has a passband of <0.7 Ångstrom, which provides the ideal balance between prominence and surface detail. Below 0.5 Ångstrom detail in prominences is less visible and the resolution and detail on the Sun’s surface is enhanced. At <1.0 Ångstrom, the passband of the PST, prominences are favored over surface detail although major surface details are still easily observable. If additional contrast is desired for observing subtle disk details (although at the expense of somewhat dimmer prominences), an optional SolarMax 40 filter can be mounted on the front cell of the PST, using a T-Max assembly (although the T-Max’s Doppler tilt function is not usable). Stacking filters in this fashion provides a narrower and higher contrast <0.6 Ångstrom passband to show even more subtle detail on the face of the Sun. The SolarMax 40 has a blocking filter with a 10mm aperture, while that of the PST is 5mm. The larger blocking filter aperture allows you to use a Barlow in front of the SolarMax 40’s blocking filter. This makes digital photography easier and allows the uses of a binoviewer with the SolarMax.

In addition, the SolarMax 40 uses an external 40mm full aperture <0.7 Ångstrom etalon that is mounted on the front objective of the telescope. It is supported by a T-MAX assembly that can be "tilted" off bandwidth to observe Doppler-shifted events. The objective itself is a special H-Alpha doublet lens designed by Dick Buchroeder (including optimized anti-ghosting). The PST, while it has a 40mm conventional doublet objective, has a smaller fixed internal 20mm <1.0 Å etalon. It has no capacity for Doppler shifting.

Another difference is in the focusing method. The SolarMax 40 uses a helical focuser that allows both visual observing and prime focus imaging. The focusing system of the PST is an internal mechanism that keeps the eyepiece in a fixed position. It is primarily for visual use, although you can do high magnification imaging with a suitable afocal set up.

To sum up the differences, you’ll see a better balance of prominence and disk detail with a SolarMax 40, will be able to use a binoviewer, and will be able to do prime focus digital camera photography, but you’ll spend over three times as much to see those improvements. The SolarMax 40 is the better solar scope. The PST is the better solar scope buy.

Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

400mm
Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

f/10
Resolution:
This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

2.9 arc seconds
Aperture:
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
1.6"
Weight:
The weight of this product.
3 lbs.
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Refractor
Warranty:
5 years
Reviews from Cloudy Nights (www.cloudynights.com)
These reviews have been written by astronomers just like you and posted on the Cloudy Nights astronomy forums . . .
Coronado PST Review

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1. Anthony on 3/13/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
Since last year's annular solar eclipse and Venus transit, I've been observing the Sun through white-light filters on my 127 mm Schmidt-Cassegrain, 70 mm refractor, and 11x56 binoculars, and with an inexpensive projecting solarscope. Watching sunspots develop and move across the face of the Sun is fun, but when Coronado put the PST on sale, I decided to step up to Hydrogen-alpha viewing. I am very happy with this telescope, and my neighbors have been impressed when I've set up on the sidewalk and offered them a look. I'm looking forward to using this telescope at upcoming solar astronomy public outreach events.

Right out of the box, the PST is a handsome instrument, with excellent fit and finish of all components. It's a very simple and easy-to-use telescope with an internal focuser controlled by a small knob, and a helical tuner for the etalon filter. The manual gives clear instructions for set-up and use. Basically you screw the PST into a mount with a 1.25"x20 bolt, point it at the Sun, focus, and tune.

I've mounted the PST on an old Celestron Alt-Az 4 mount with fine-motion controls, and this rig works fine. The PST is very light, so you don't need a heavy mount. It would probably work on a sturdy photo tripod, but the fine-motion controls on the Alt-Az 4 make tracking the Sun for extended observation much easier.

Aiming the telescope at the Sun is easy. Use the shadow of the telescope for rough alignment, then the PST's simple little solar finder puts a bright white dot in the middle of a small translucent window when the telescope is pointed at the Sun.

The included 20 mm Kellner eyepiece gives an adequate view, but higher quality, shorter focal length, and wider apparent field of view eyepieces offer much better views. Using an Explore Scientific 14mm 82-degree AFOV eyepiece provides 28x magnification and a 2.87-degree field of view. This seems to be the sweet spot among my eyepieces. The entire 0.5-degree Sun fits easily in the field, with room to drift across the field for over a minute before you need to track (if you use a tracking mount you might be able to push the magnification higher). The amount of detail seen in the prominences on the Sun's limb was truly impressive, you can see shimmering wisps and curtains of gas. Tuning the etalon to a slightly different wavelength highlights dark sunspots and filaments and brighter plages on the Sun's surface. There really is nothing like watching the Hydrogen gas in the Sun's atmosphere!

Coronado offers an expensive eyepiece set custom-made for solar viewing. I haven't tried these eyepieces, but I'm quite happy with the view through my Explore Scientific eyepieces. If you already have quality eyepieces I would suggest trying the scope with your existing eyepieces before deciding whether you need more eyepieces.

The $100 case Coronado offers with the PST seemed overpriced, so I didn't buy it. My telescope shipped in a compact double cardboard box with a durable high-density foam cut-out for the telescope, plus room for accessories. If you buy the case you take the foam out of the shipping box and put it in the case. I'm using the original boxes as my case, and the seem to work fine, even though a plain cardboard box might not look as impressive as the case.

But what is impressive is the view of the Sun through this little telescope. If you want to get into Hydrogen-alpha viewing on a budget, I would recommend the PST.
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2. Mike on 9/15/2012, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
The only drawback for the PST is it relatively small aperture, but it is a surprisingly good value in H-alpha solar viewing. For those interested in breaking into solar astronomy at a reasonable cost there's really nothing to compare with it.
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General Accessories
Altazimuth Mounts (1)
DS Mount For solar observing with Coronado solar scopes
by Coronado Instruments
Quantity:  
$229.00 
Telescope Carrying Cases (1)
Carrying Case for PST (Personal Solar Telescope)
by Coronado Instruments
Quantity:  
$99.99 
Visual Accessories
Eyepieces (3)
18mm CEMAX 1.25" enhanced for solar viewing
by Coronado Instruments
Quantity:  
$79.99 
12mm CEMAX 1.25" enhanced for solar viewing
by Coronado Instruments
Quantity:  
$79.99 
25mm CEMAX 1.25" enhanced for solar viewing
by Coronado Instruments
Quantity:  
$79.99 
  • Dust cover
  • Built-in solar finder
  • 20mm 1.25" Kellner eyepiece
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Coronado Instruments - Personal Solar Telescope, 1.6" F/10 refractor with built-in <1.0 Ångstrom H-alpha filter

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Coronado Instruments - Personal Solar Telescope, 1.6" F/10 refractor with built-in <1.0 Ångstrom H-alpha filterA closeup of the PST, showing the focus knob at the lower left, the round screen of the built-in sun finder, the rotary collar for fine-tuning the filter performance, and the thread-in lens cap.PST solar image, courtesy Coronado. The prominence appears as it does to the eye through the scope. An image of the Earth to scale has been added to show the size of the prominence.PST solar image, courtesy Coronado. A combination of two images, one exposed for prominences, one for disk detail. The prominences appear as they do to the eye through the scope.PST solar image, courtesy Coronado. A combination of two images, one exposed for prominences, one for disk detail. The prominences appear as they do to the eye through the scope.PST solar image, courtesy Coronado. A combination of two images, one exposed for prominences, one for disk detail. The prominences appear as they do to the eye through the scope.
 AstronomicsAstronomicsAstronomicsAstronomicsAstronomics (Average: 4.50 | Users: 2)  Only registered users can submit ratings - Register Here
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The Coronado Personal Solar Telescope is a complete solar observing system – telescope, eyepiece, and sub-Ångstrom H-alpha solar filter for viewing flares and prominences – all for less than the cost of a single premium conventional eyepiece . . .





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