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Coronado PST Review

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#1 Charlie Hein

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Posted 08 December 2012 - 11:00 AM

Coronado PST Review

By Tristan Schwartz

#2 David Knisely

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Posted 08 December 2012 - 01:50 PM

Not a bad review, similar to the one I posted in 2004 as the PST first came out:

CN REPORTS: The Coronado PST "Personal Solar Telescope"

I agree that the 20mm Kellner that comes with the current PST is way too long a focal length to be very useful. I would go with using a 15 mm to 9 mm focal length eyepiece or a zoom eyepiece for solar work. One point however is that there is no "granulation" seen with the H-alpha sun. What is being seen on the disk away from active regions is know as the "dark mottles"; a network of very fine structure consisting of spicules, fibrils, and very short filaments in the chromosphere (sometimes referred to as the "orange peel" effect). Actual granulation is a somewhat smaller-scale white light feature visible in apertures of three inches and larger, so it is beyond the resolution of a 40mm aperture. Even in larger scopes with a sub-angstrom H-alpha filter, granulation is not seen since you are looking at the Chromosphere and not the photosphere where the convection leading to the granulation feature primarily takes place. Clear skies to you.

#3 Special Ed

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Posted 08 December 2012 - 02:33 PM

Just wanted to say that Tristan Schwartz's review reflects my own experience with my PST accurately, right down to the off-center finder.

I've had my PST since 2005 and the only problem in that time was I had to send it back to get the rust issue repaired (at no cost).

I share Tristan's enthusiasm for observing in H-alpha. Everyone should at least try it--but be careful...you could get hooked.

#4 MikeBOKC

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Posted 08 December 2012 - 03:05 PM

The PST is one of the best values in amateur astronomy! It is also very handy for piggybacking with a small refractor for simultaneous white light viewing. This rig was a real hit at the Venus transit in June:

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#5 Scott in NC

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Posted 08 December 2012 - 03:30 PM

Nice review, Tristan--thanks for sharing that!

#6 psi_chemie

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Posted 21 December 2012 - 08:12 PM

I found Tristan's description of the tilt tuning excellent- I had been left confused about this from some other reviews. I am not afraid of getting a tilt-tuning unit now, I was going to spring for pressure tuned.
Thanks.

#7 Rick Woods

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Posted 22 December 2012 - 01:29 PM

The PST is one of the best values in amateur astronomy! It is also very handy for piggybacking with a small refractor for simultaneous white light viewing. This rig was a real hit at the Venus transit in June:


That's the same setup I have, except it's an old orange C8 w/white light filter instead of a refractor. It was great for the Venus transit!

#8 Rick Woods

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Posted 22 December 2012 - 01:50 PM

Good review!
My PST doesn't have any of the drawbacks he mentions. The focuser knob is fine with me as it is; and the Sol Finder puts the sun pretty much dead center in a high-power eyepiece.
I find that my Meade S4000 8.8mm UWA eyepiece is the perfect match for the PST, and it's pretty much the only one I use. I also keep a couple of plossls with it, but they don't get used much.
I bought a carrying case after the fact, and I really like it, too. It's pretty light, as Tristan says; but for transporting the unit, I put the whole thing in a heavy cardboard box. For use at home, the case is perfect, as well as nice looking.

As for the views, it's wonderful! I doubt I'll ever get a bigger solar telescope, but I might get the double-stack filter at some point.
The Sun and the Moon are the only objects that change minute to minute. It's well worth it to have the means to follow both closely.

#9 Pentax Syntax

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Posted 24 December 2012 - 07:21 PM

Coronado PST Review

By Tristan Schwartz


Nice Review Tristan,

I fully agree with most of your comments. A minor difference is that my PST has a fairly well centered finder. Like yours, mine came with a cheap 20 mm eyepiece. I find that a Takahashi LE 12.5 is about the sweet spot for the scope. Most eyepieces work well on the PST though; my 17.5 MA and 9 MA work almost as well as the Takahashi even though they would be just a dust plugs on my other scopes. My most often used eyepiece with the PST is an older Vixen 8-24 zoom. That single eyepiece covers the entire useful range of the PST. So far, I have avoided the temptation to double stack mine but who knows what the future will bring.....

#10 Zamboni

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Posted 08 January 2013 - 03:34 PM

Thanks for the kind words and the granulation correction. The more I use this scope the more addictive it gets.

One eyepiece that I tried out in a friend's PST that seems to hit a really good balance is the 9mm Zhumell long eye-relief. Doesn't work at all for afocal imaging, but is fantastic for observing.

My next big astronomical purchase is going to be a 100 to 120mm refractor on a CG5. I plan to get a Lunt herschel wedge for it and then piggyback the PST. Should make an impressive solar observing rig, especially for outreach.

#11 Zamboni

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Posted 23 April 2013 - 02:09 PM

Update to my review:

As I continue to use this scope, the more I love it. I have added the Criterion focus knob and it makes life with the telescope SO much easier. I've also taken to using a blackout curtain over my head (dark on one side, white on the other) while observing. I find it a more complete solution than using a sunshield.

I did try mounting it on a borrowed small EQ mount recently, but the eyepiece does wind up at awkward positions occasionally as the eyepiece is non-rotatable. I may eventually get a small Goto altaz like an iOptron Cube or a Celestron NexStar SLT for tracking.

#12 jrbarnett

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Posted 23 April 2013 - 03:07 PM

Nicely done, Tristan. I too recently became a PST owner. I went the double stack route, and having compared DS to SS for a couple of weeks now, I'd say that each has its merits with such a small aperture scope. The biggest advantages of DS'ing is that you can get can view both surface detail and prominences simultaneously rather than tuning between them, and more and finer details are visible. The biggest disadvantages of DS'ing are a considerably dimmer image, imbalance of the OTA (the second etalon is quite heavy), and because of the tilt-tilt tuning designs of a DS'ed PST, you get banding; that is the higher resolution appears in a swath that you can tune or re-position for different parts of the solar disk.

All in all it's a very simple, tidy, fun to use, affordable solution.

Regards,

Jim

#13 David Knisely

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Posted 23 April 2013 - 03:42 PM

Nicely done, Tristan. I too recently became a PST owner. I went the double stack route, and having compared DS to SS for a couple of weeks now, I'd say that each has its merits with such a small aperture scope. The biggest advantages of DS'ing is that you can get can view both surface detail and prominences simultaneously rather than tuning between them, and more and finer details are visible. The biggest disadvantages of DS'ing are a considerably dimmer image, imbalance of the OTA (the second etalon is quite heavy), and because of the tilt-tilt tuning designs of a DS'ed PST, you get banding; that is the higher resolution appears in a swath that you can tune or re-position for different parts of the solar disk.

All in all it's a very simple, tidy, fun to use, affordable solution.

Regards,

Jim


Well, it isn't really higher resolution so much as it is a swath of narrower passband width of the filter. The band like structure is sometimes called a "sweet spot" where the filter's transmission curve is narrowest, causing greater contrast in the disk detail. The instrument's resolution is still that of a 40mm aperture. Clear skies to you.

#14 Zamboni

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Posted 23 April 2013 - 03:57 PM

Nicely done, Tristan. I too recently became a PST owner. I went the double stack route, and having compared DS to SS for a couple of weeks now, I'd say that each has its merits with such a small aperture scope. The biggest advantages of DS'ing is that you can get can view both surface detail and prominences simultaneously rather than tuning between them, and more and finer details are visible. The biggest disadvantages of DS'ing are a considerably dimmer image, imbalance of the OTA (the second etalon is quite heavy), and because of the tilt-tilt tuning designs of a DS'ed PST, you get banding; that is the higher resolution appears in a swath that you can tune or re-position for different parts of the solar disk.

All in all it's a very simple, tidy, fun to use, affordable solution.

Regards,

Jim


Well, it isn't really higher resolution so much as it is a swath of narrower passband width of the filter. The band like structure is sometimes called a "sweet spot" where the filter's transmission curve is narrowest, causing greater contrast in the disk detail. The instrument's resolution is still that of a 50mm aperture. Clear skies to you.


This. The difference is really one of contrast rather than resolution (although the PST is 40mm, not 50mm). Still, the contrast difference is pretty astounding. In spite of the dimmer view, double stacking makes a heck of a difference. I looked through a double stack PST last year at the big Albuquerque star party for the May 20th annular eclipse. The difference was almost shocking.

In spite of some stiff competition (performance-wise) from the LS35 these days, I think the PST is still a brilliantly designed scope for being a self-contained, no guesswork H-alpha beginner rig.

#15 David Knisely

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Posted 23 April 2013 - 04:32 PM

Nicely done, Tristan. I too recently became a PST owner. I went the double stack route, and having compared DS to SS for a couple of weeks now, I'd say that each has its merits with such a small aperture scope. The biggest advantages of DS'ing is that you can get can view both surface detail and prominences simultaneously rather than tuning between them, and more and finer details are visible. The biggest disadvantages of DS'ing are a considerably dimmer image, imbalance of the OTA (the second etalon is quite heavy), and because of the tilt-tilt tuning designs of a DS'ed PST, you get banding; that is the higher resolution appears in a swath that you can tune or re-position for different parts of the solar disk.

All in all it's a very simple, tidy, fun to use, affordable solution.

Regards,

Jim


Well, it isn't really higher resolution so much as it is a swath of narrower passband width of the filter. The band like structure is sometimes called a "sweet spot" where the filter's transmission curve is narrowest, causing greater contrast in the disk detail. The instrument's resolution is still that of a 50mm aperture. Clear skies to you.



This. The difference is really one of contrast rather than resolution (although the PST is 40mm, not 50mm). Still, the contrast difference is pretty astounding. In spite of the dimmer view, double stacking makes a heck of a difference. I looked through a double stack PST last year at the big Albuquerque star party for the May 20th annular eclipse. The difference was almost shocking.

In spite of some stiff competition (performance-wise) from the LS35 these days, I think the PST is still a brilliantly designed scope for being a self-contained, no guesswork H-alpha beginner rig.


I hate typing (the "5" key instead of the "4" that I wanted to hit). Yup, while I do have a 90mm aperture Mak-Cassegrain equipped with a DayStar T-scanner, I still end up using my PST more because it is so easy to get up and running for a quick look. Now, if the clouds would only go away for a while... Clear skies to you.

#16 jrbarnett

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Posted 23 April 2013 - 05:51 PM

Sorry. I was using "resolution" generically in a plain English rather than in a technical optics sense. You're right that the filter alters the contrast, not the resolving power, of the instrument.

I've read that Lunt's pressure tuning system reduces of eliminates the "sweet spot" issue when DS'ing, though I haven't used a pressure tuned Lunt.

I did try a Lunt 35, but it arrived damaged (the third damaged H-alpha scope/filter in a row that I received from the same vendor before abandoning H-alpha aspirations for a year; bad shippers in San Diego). The other damaged scopes/filters were a Coronado 60 and a Solar Scope 50 filter/blocking filter combo.

This time I ordered from stock from a different vendor who opens and verifies the condition of each Coronado scope they sell to avoid the QC issues they were otherwise hearig about from customers. I am glad that I did too. The PST DS works as advertised. I was very relieved.

I'll get some pictures up of my side-by-side set-up. I use a PST SS/DS with an L-bracket on one side and a 60mm f/7 triplet plus Herschel wedge on the other side of a smooth, simple alt-az mount. I also have a Nexstar 6/8 SE alt-az mount that I will eventually use with the PST. To accommodate the balance shift using the DS second etalon, I need a longer Vixen-style dovetail first, though.

Regards,

Jim

#17 Zamboni

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Posted 23 April 2013 - 06:05 PM

That's awful to hear about the damage issues from the dealer. If I ever get a Lunt scope, I'll probably order direct from the manufacturer because they apparently pack stuff particularly well.

I have played around with pressure tuned LS60s, LS80s and an LS152. Pressure tuning isn't available on the 35, tragically. It works very much as advertized, eliminating sweet spots. The bandpass is also narrow compared to other single-etalon systems, falling around the .6 Angstrom range. The contrast is spectacular, but all but one of the pressure tuned Lunts I've looked through had a gauzy glow around the solar disk. This had a mildly adverse affect on prominence contrast. YMMV.

In spite of that, the Lunt scopes are pretty amazing when they aren't damaged. The view through the LS152 was staggering.

#18 spaceydee

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Posted 01 May 2013 - 10:02 AM

When I used to take the PST out.. (stopped because I was afraid of being attacked by wasps!!) I used to do my observing with the single stack first, then add the double stack on. I love that scope, really it was an excellent purchase for me.

That is an excellent first image of the sun by the way!!

#19 Undermidnight

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Posted 01 May 2013 - 01:31 PM

Loved the review. I recently just got back into Ha observing with a PST that was used (but brand new) from an estate. This will be my third one (I won't be selling it). It has a wonderful view in it and I want to start imaging with it. Your picture in the review is really good! I want to start imaging with my PST.

Jason

#20 Zamboni

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Posted 03 May 2013 - 06:22 PM

One thing about imaging with the PST is that it's very hard to get an image with a CMOS camera without the image suffering from Newton rings. That'll be the most challenging aspect for most PST imagers.

I have had some moderate successes, though. Here's one I took today holding my Canon Powershot point and shoot to the eyepiece. I may get a good afocal adapter and start taking video and then frame stacking with registax.

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#21 davidpitre

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Posted 05 May 2013 - 06:42 PM

I've also taken to using a blackout curtain over my head (dark on one side, white on the other) while observing. I find it a more complete solution than using a sunshield.

I've gotten to where I consider the blackout cloth an essential solar accessory. For night time it is a luxury, for day time it make all the difference in the world. Especially when sharing the view with the inexperienced, the cloth makes a huge difference.

#22 Startraffic

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Posted 07 May 2013 - 06:37 AM

Ok, I was a bit skeptical until Saturday afternoon. I had gotten a PST & finally got the chance to use it. Completely crummy weather, wind blowing at 20-25 knots, gusting to 35. A flimsy Alt/Az camera tripod, with spaghetti legs, & no motion controls, but very light & portable since I was camping with the Boyscouts. Most of the boys came & looked a couple were awestruck. I started with a 40mm. Ok, nice but nothing to write home about, I get as good with a 8"f4 & a TO glass filter. 20mm better, I saw a few sunspots, & then, a flare on the edge at about the 5:30 position! Switch to a 9.6mm, ok I'm sold! That was too cool to be able to watch it moving. It'll have a permanent place on the HGM. To the right of the 8"R200ss & the C6R. Any reason I can't mount it on its' side, other than finding a 90* mounting bracket? The would put the EP in a more usable position.

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#23 David Knisely

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Posted 07 May 2013 - 02:47 PM

Ok, I was a bit skeptical until Saturday afternoon. I had gotten a PST & finally got the chance to use it. Completely crummy weather, wind blowing at 20-25 knots, gusting to 35. A flimsy Alt/Az camera tripod, with spaghetti legs, & no motion controls, but very light & portable since I was camping with the Boyscouts. Most of the boys came & looked a couple were awestruck. I started with a 40mm. Ok, nice but nothing to write home about, I get as good with a 8"f4 & a TO glass filter. 20mm better, I saw a few sunspots, & then, a flare on the edge at about the 5:30 position! Switch to a 9.6mm, ok I'm sold! That was too cool to be able to watch it moving. It'll have a permanent place on the HGM. To the right of the 8"R200ss & the C6R. Any reason I can't mount it on its' side, other than finding a 90* mounting bracket? The would put the EP in a more usable position.

Clear Dark Skies
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39.138274 -77.168898


The PST can be placed in almost any position that is convenient for you. Some people cobble together a circular bracket that goes on the gold tube to allow the PST to be rotated, although you kind of have to watch where this goes, as it can interfere with the PST's tuning ring. Be sure you use that ring a lot, as you will see different features and contrast on the disk as you adjust it. For eyepieces, I rarely use anything longer than 20mm focal length in my PST, and my favorite range is between 12mm and 7mm (I use a zoom eyepiece most of the time). As for "a flare on the edge", you probably saw what is known as a prominence: H-Alpha emission features projecting beyond the limb of the sun, consisting of complex clouds or streamers of magnetically-confined gas above or in the chromosphere. They generally come in two broad classes: Active (limb flares, surges, sprays, loops), and Quiescent (Quiet Region Filaments, Active Region Filaments). For more information about what is visible in H-alpha, the following article may be of some help:

Observing The Sun In H-alpha

Clear skies to you.

#24 REC

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Posted 07 May 2013 - 03:56 PM

David, thanks for the link as I am also a newbie with the PST. Really enjoying the daily views and changes going on everyday. For me, I like the 11-16mm EP range so far.

Bob

#25 Startraffic

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Posted 08 May 2013 - 12:43 PM

Dave,
Thanx for the link a good read & it helped a lot. Looks like it's going to take a lot more observing to get myself educated as to what I'm seeing. A whole new vocabulary to learn.

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