Last updated: 29 June 2006
In October 2004, I purchased a "PST" or "Personal Solar Telescope" made by Coronado Filters from OPT. I have been observing our Sun in white light with my ETX-90RA using the Thousand Oaks and Coronado white light filters and felt it was time to venture into Hydrogen-Alpha (or H-Alpha) viewing. The PST is a complete H-Alpha telescope for safely viewing the Sun. While there is no tripod there is a standard tripod mounting hole (two in fact) on the bottom of its base so that you can use any photographic tripod or even piggyback it to another telescope using a piggyback camera adapter. It comes with a 12.5mm Kellner eyepiece, which provides a full disk view with this 40mm f/10 system. The filtering is about 1.0 Angstrom, which isn't as nice as higher end (that is, higher priced) H-Alpha telescopes, but it certainly provides nice views for the price. But lets start at the beginning.
The photo above shows the packaging for the PST. The box is informative with photos and explanations of surface details. While the images may not have been taken through a PST they are indicative of what you will see when viewing through a PST.
This photo shows the packing for the PST and its eyepiece. The packing can be used with an optional case and includes cutouts for a tabletop tripod and two more eyepieces. The PST is very tightly secured in its compartment; I found it difficult to remove the PST while being concerned about damaging the telescope. I finally managed to work it out of its slot. The documentation includes a simple but adequate manual, a shipping warning, and a warranty card that must be returned to Coronado to get the 5 year limited warranty.
Since the Sun was shining brightly today I was able to actually use my new telescope! (As we all know, it typically rains after getting home with a new telescope.) I mounted it on a standard photographic tripod as shown in the photo below.
This provided a nice stable platform from which to test out my new PST. I pointed the telescope at the Sun and then refined the pointing using the sun finder (which Coronado calls a "Sol Ranger"). The Sol Ranger provides a safe point of the Sun's light (seen above the eyepiece in the photo below) and when centered should put the Sun's image in the 12.5mm eyepiece field of view. In my case it was perfectly centered in the eyepiece. Also seen in this photograph is the "tuner", the knurled ring at the end of the gold tube. I'll discuss this later. Focusing is smooth using the large knob on the bottom back end of the base (the silver knob just visible under the eyepiece in the photo above).
The view through the PST with the supplied 12.5 eyepiece was awesome! I could easily see two distinct prominences on the Sun's edge, a nice grouping of sunspots, and a filament (a prominence seen edge-on). Lots of details were visible on the Sun's surface. Later as I became more familiar with viewing the Sun in H-Alpha I was able to pick up fainter prominences on the solar limb.
I then tried a quick afocal photograph using my Nikon Coolpix 995 held up to the eyepiece. While not great it does show two prominences:
Now that I knew the PST was working as it should, I then mounted it on my ETX-90RA using the JMI piggyback camera adapter, as seen in these three photos:
The PST is light enough to not cause any problems with tracking or slewing the ETX-90RA. Unlike when mounted on the photographic tripod, the ETX compensated for the Earth's rotation and so it was not necessary to manually move the PST to keep viewing the Sun. The middle photo above clearly shows the Coronado White Light Solar Filter covering the ETX aperture. In addition, piggybacking the PST on another telescope can provide easy viewing of the Sun in both white light and H-Alpha, making it convenient to view different features. When I firsted mounted the PST to the ETX the optical paths of both telescopes were well aligned to each other. However, for some reason, the alignment in declination changed after I attached the Coolpix via the Scopetronix Digi-T for afocal photography. I was unable to get the optical paths realigned. I will have to investigate this more.
I took a quick afocal photograph with the Coolpix 995 mounted with the Digi-T to a 25mm eyepiece plus a wide field adapter on the ETX. This shot (not ideal) was through the white light filter. You can see two sunspot groupings.
I then mounted the same camera/adapter/eyepiece on the PST with this result:
You can see several prominences around the solar limb. I do have to work on the focus as well as the exposure but I ran out of time for today's initial outing with the PST. I hope to be able to work more with the PST next weekend and will post additional photos when I have them.
I then tried several Meade eyepieces with the PST. While the 12.5mm that is supplied with the PST provides a nice full disk view, the standard 26mm included with the ETX also did a nice job although the size of the solar disk was smaller, making details difficult to see. The PST includes a "tuner" to adjust the contrast of the light and it was necessary to slightly adjust this by rotating the tuner ring when using different eyepieces. The Meade 6.4mm allowed increased magnification on the prominences but was generally too dim for efficient use. I settled on the Meade 9.7mm for providing higher magnification than the 12.5mm while retaining easy visibility of features.
For visual use, the PST provides amazing views of H-Alpha details on the Sun. Photographs are possible (although I need to work on that!). Piggybacking the PST really enhances the enjoyment by eliminating the need to manually correct for the Sun's movement across the sky. If you have a white light solar filter for that other telescope you get the best of both worlds.
If you are interested in starting in H-Alpha observing of our dynamic Sun, the PST is a great entry level telescope. Its minimal weight and ease of use will greatly increase your enjoyment for those spur-of-the-moment occasions when you want to show off our Sun to your friends and neighbors.
Subject: Coronado P.S.T. Sent: Thursday, August 4, 2005 08:47:48 From: Dieter.Wolf@DNSint.com (Dieter.Wolf@DNSint.com) I know you own a P.S.T. (I read your article from 2004) - so, what do you think about a 'Coronado' column on your ETX site??? Here in Germany the 'Hydrogen Alpha Feaver' is spreading and the community of P.S.T. fans grows. I bought mine a few days ago. Of course I will not be angry if you say that is not your stuff, but if you want to add CORONADO stuff to your website, here is my first posting. Coronado P.S.T. - first experiences When I brought mine home from a local MEADE dealer a few days ago late in the evening I quickly unpacked the scope and found it heavier than I expected (about 1.4 kg) and solid and well done. Then I mounted it on a standard tripod (two mounting holes at the bottom) and did not expect to see too much. By the way: very usefull solar finder; just safely center the light dot - that's all. Then I saw prominences. Well, not comparable to the view through my 20x80 binoculars in 1999 during total solar eclipse, but still a 'wow'. A great little solar scope. Some ideas - things I learned: - put the P.S.T. on any camera tripod for quick views; that works fine and you're ready to go in 5 minutes - forget about the 12mm Kern ocular - you have a 26mm SP somewhere from any other MEADE telescope: use it, it gives a fine, sharp view of the total sun - you have any other ocular in the range of 16...9mm: that's fine for a detailed view - you want to mount the P.S.T. on top of an ETX: a piggy-back camera adapter works fine at least with the 90-105-125 range of ETX telescopes; maybe it's hard for the motors of a 70; but try to use an adapter that has the extra load of the P.S.T. as far to the back (ocular) side of the scope as possible, this helps balancing - you want to take photos: don't try ToUCam's, Atik's or similar at prime focus - you can't get into focus; you can use any telenegative lense but calculate a 2x barlow with the ToUCam results in about 100x magnification; too much for a 40mm scope - you want to take photos part 2: try afocal / eyepiece projection; that works with digital cameras and / or webcams, but even with that you MAY not be able to get into focus if the ocular does not get 'deep' enough into the scope (as happened to me with MEADE variable camera adapter) - about colors: don't try to get 'natural colors' (decrease red) because RED is all the information you got; blue and yellow is just noise - to focus (it's more difficult than with white light) you have to choose between sharp central part of the sun or sharp prominences; you probably woun't get both at the same time even not with finetuning the Etalon filter (the 'ring' on the scope) - it's a good idea to keep yourself, your camera, notebook, etc. off direct sunlight otherwise it's hard to see anything on LCD's - it's much more comfortable to view in the morning / evening hours than around high noon I have to learn and try very much but dont want to close this without showing my - very bad - 'first light shot' and the 'professional setup' that made it possible (my wife came creeping up on tip toes)...I like Hydrogen Alpha observation with this litte scope; you too? Dieter (Munich, Germany)
Subject: Correction to Coronado PST review Sent: Wednesday, June 28, 2006 12:50:09 From: Steve Taylor Just a quick note - on page #1 of the Coronado PST review, last updated on August 4, 2005, the paragraph below the photograph of the PST box is incorrect. All of the photos on the PST box were created with a standard, off-the-shelf PST, taken by Gary Palmer ( www.solarminimum.com) with post-production done using Image Stacker and Photoshop 7. This is clearly noted right on the box. Thought you'd want to know. It's pretty incredible that those images are done with a stock unit! I just received my new PST yesterday and MALTA mount today... and finally, for the first time in a LONG time, we have sunshine! I live outside of Washington, DC - in suburban Maryland - and we've had tremendous heavy rains with flooding for many days. I only had 15 minutes to quickly set up and try out my new PST and, using the now 20mm included eyepiece (used to be 12mm eyepiece but now all PST's include 20mm) was able to clearly see the beautiful, stunning, angry red image of our nearest star and clearly saw small sun spots towards the right hand side. It was stunning and I cannot wait to try my other ETX-80AT supplied eyepieces with this scope this afternoon. Thanks for your site - it's a chock full of information and great, helpful fellow users. Sincerely, Steve Taylor maclifer(at)gmail(dot)comMike here: Thanks! My box doesn't say that. It says "Solar images by Jack Newton www.jacknewton.com" and doesn't say they were done with the PST. Maybe new boxes have different photos.
Sorry about that - I didn't realize that boxes had changed. :-) The new box says exactly the following on it: "Solar images provided by amateur astronomer Gary Palmer, www.solarminimum.com, using an off-the-shelf P.S.T. Post-production done using Keith's Image Stacker and Photoshop 7." Thanks for your site. I was surprised to find the PST review on it. I had a brief chance at first light yesterday with my PST and was simply amazed at just the few (3 or 4) minutes I had to use it with the, newly included, 20mm eyepiece (the 12mm is no longer standard with the scope).
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