Posts Made By: Jim Richberg

Looks like it would work fine, as long as you've got PST's of comparable resolution. With units randomly coming in between 1.0 and 0.6 Angstroms, though, it could be tough to implement successfully in practice...

I don't have the latest S&T in front of me, so I can't check the ad out, but the old $25 Apogee orthos supposedly featured the same glass from the same little factory in Japan that made the near legendary Meade Research Grade orthos. Not sure whether there was truth to this or not, but I had the 10.5mm of both and found their performance comparable -- and they were parfocal. Apogee and the Meade RG were also the only orthos I ever saw that came in the unusual 16.8mm focal length.

More recently, Apogee's $49 zoom eyepiece was supposedly an OEM version of the Nikon zoom costing 3-4X as much. I own the Nikons, but was unable to get an Apogee to verify this report first hand before they went out of stock indefinitely.

The point to all of this is that Apogee sometimes seems to have the knack of finding high grade optics for a cut-rate price.

Jim

I've talked to Nick about this, and my choice is either to believe him, or believe my eyes. Guess which I'm going with?
I mean, my eyes have done a pretty good job for me these past 44+ years, and that includes nearly 30 using them critically as an astronomer.

Let me tell you my story...
I actually owned a Maxscope 40 and purchased a PST to stack the SolarMax filter on. With that in mind, I was baffled that in idle A/B testing before doing the stacking, the PST seemed to render both better resolution and a brighter view than its Maxscope brother. This pertained both to prominences and surface features. I chalked this up to a quirk, stacked the two-- and found the view little if any better than that of the unstacked PST! (It was markedly dimmer, and may have shown a touch more resolution, but it wasn't something I could conclude definitively-- it was that subtle or marginal.) I chalked this up to an aberration, but when it happened on my next ten observing days under a variety of atmospheric conditions, I decided it wasn't a fluke.

I then got together with a very seasoned solar observer. I believe may have told him I had some doubts about my PST's performance, but am virtually certain that I didn't tell him which way I suspected it was "off", so his observations should not have been biased by any preconceptions from me. He took one look, commented that this was the best of any of the two dozen PST's he'd looked through, and that we were seeing all of the spicules and similar features (albeit at a lesser magnification) as he'd seen a few minutes prior in his SolarMax 90-equipped scope.

I've subsequently had the opportunity to test my PST against others, both stacked and unstacked, and have seen nothing to change this impression. What I haven't had the chance to do is compare it to a doublestacked Maxscope 40, but it certainly beats every other PST I've encountered-- both in my eyes, in those of independent observers, and in the eyes of the owners of the other PST's. There appear to be other PST's that show this performance level, too, as born out by other owners in this forum who have tried or purchased Solarmax filters and concluded that the stacking really didn't enhance their view.

Maybe Coronado claims this level of performance is impossible... I know that's what they told me. :S However, I'm going with the empirical evidence over the manufacturer's claims on this one.

Jim

Vaclav G Novotny said:

8)
My two cense worth
I had a chance to check out some (about 5) PST about 6 months ago when they were in short supply and on back order and compare them with a maxscope40
I found that they varied in preserved bandwidth some were better some were the same and some were not as good as the maxscope40
About 2 weeks ago I compared a new batch of 10 PST to a maxscope40, they were all not as good and all about the same preserved bandwidth.
I personally think that when they were in short supply some higher quality (smaller bandwidth) were sent out but now the rush is over I think all of them are now exactly as per specification.

Be careful here, Vars; you're getting into the same boat I'm in, and will have folks telling you that you that you really didn't see those discrepencies after all. :S
Remember, you're supposed to believe the the pundits instead of your own eyes.

For what it's worth, I think all the "impossibly good" PST's (let's call them 'unicorn scopes', since they may be mythical, eh? ) we're talking about were sold in and probably manufactured in 4Q of 2004. From what you've said, it seems like they're spot on their normal spec now.

Hope you're having as much fun with your 'unicorn' as I am with mine!

Jim

Try Bob Fies-- he does the coating for John Dobson's Sidewalk Astronomers. His prices are reasonable, and he's close enough to you (San Carlos) that you might be able to drop the mirror off vice shipping it.
His URL is http://home.covad.net/~alcoat/
Good luck,

Jim

Kwang, it won't quite get to your 8 foot minimum height, but Jim Fly's "Cat's Perch Pro" chair http://www.catseyecollimation.com/cperch1.html has a maximum height of 46.2", and has an built-in adjustable footrest you can use to climb onto the chair when it is set in these high seating positions. Jim has stopped selling the finished chairs and hardware kits, though, so you'd have to buy the plans and build it yourself.

Depending on how tall you are, this can get you close to your minimum height requirement-- I can see level into a eyepiece 84" (7 ft) off the ground using my chair, and I find it relatively easy to get onto--though a bit tougher to jump down from, especially when bellied up to a scope. It might be a viable option, though, if you opt to go for a 16" scope of ~f/5.5 or thereabouts.

For what it's worth, I went through the same experience you're contemplating, and ended up owning a 20" f/6.7 for a couple of years. I found that the additional coma-free field of view did not make up for the hassles of dealing with the ladder. (There also wasn't enough extra light grasp beyond my 16" to justify it either, but that's a separate issue.) Your mileage may vary.

Good luck!

Jim

I'd personally vote for the PST, as the best combination of bulletproof and lending a "wow" view. I've shown hundreds of people views through my PST, some of whom had just looked through a 90mm Coronado scope piggybacked atop a 0.2A Daystar filter on a big AP refractor. (Yes, Greg, I'm talking about you!) None said "boy, this view stinks... I don't see any prominences" when using the PST, even on the heels of having viewed through a "Cadillac" rig.

On the other hand, there are enough of us who are local to the Smithsonian that you could probably hold a "shoot out" and decide for yourself.

Jim

Paulo martin said:

Hello,

This is my question.A 6" f/5 refractor is good for DSO wide field?
For nebulas, star cluster..

Paulo

Ah, someone else starts down the road towards a "Richest Field Telescope"!

My short answer is "yes" depending on what eyepieces you've got or are willing to buy. An f/5 refractor will be pretty hard on eyepieces in terms of astigmatism; this is mitigated somewhat when you are using the scope on DSO's vice stars/planets and at low power, but you'll still probably find that Naglers and other expensive eyepieces work the best on these scopes. Buying an eyepiece that costs significantly more than the scope is not necessarily part of your viewing equation-- but if you've already got these eyepieces, adding an f/5 refractor can be a great way to get a Richest Field view.

I recently picked up an Orion 120mm f/5 here on Astromart, and modified it pretty heavily.
http://www.jimrichberg.com/astronomy/Orion%20ST120.htm

I already had a Nagler 31 and high end 2" diagonal (AP MaxBright), so for a $300 outlay I got a scope that yielded a 4.24 degree field of view at 19 power. This is a useful companion to my big Dob (24" f/4) at deep sky sites, since the big scope can't crack the 1 degree FOV barrier even with the Nagler 31. I've found that the ST120 rendered appreciably better views than smaller refractors (70 and 80mm). The 6" f/5 you're looking at reaches about 0.5 magnitude deeper in terms of light grasp, but at the cost of width of Field of View (3.4 degrees using the Nagler 31).

So yes, I think you're on the right track if you're looking for a dedicated DSO/Rich Field scope, but you might want to crunch the numbers (cost and performance) on slightly smaller (~120mm) refractors as well.

Jim

Shortly after the PST came out another solar geek and I tested a handful of eyepieces--
3-6mm Nagler zoom set at 6mm,
TMB Super Monocentric 6mm,
7mm Type 6 Nagler,
9-21mm Nikon zoom, and
Coronado's Cemax 12mm with and without the Cemax Barlow

We found that the zooms offered the same level of optical performance as the best fixed focal length eyepieces, plus of course the convenience of easy multiple magnification.

Given that Zooms as a class seem to be ideal for the PST, I wondered if one could choose between the various zoom eyepieces based on price and performance. I tested five zooms on a great (0.5 A resolution) PST and compared their sharpness, light throughput, and various usability aspects for example, some require two hands to zoom).

My results in terms of performance (ignoring price) were--

First place tie: Nikon 9-21mm and Pentax 8-24mm

Third: Proxima 8-24mm (Hands On Optics)

Fourth: Apogee 7.3-22mm

Fifth: Televue/Orion/Vixen 8-24

You can read the whole test on my web site
http://www.jimrichberg.com/astronomy/zoom_eyepiece_solar_review.htm

The test of fixed vs. zoom eyepieces in the PST is at
http://www.jimrichberg.com/astronomy/solar%20eyepieces.htm

Jim

Since are a number of plans for these ground boards available on the Web and guys in my Club have successfully built them, I decided to give it a try myself on one of my scope building projects. After all, it looked straightforward, and I'm a reasonably handy guy.

What a nightmare it turned out to be-- I spent *far* more time on this than any other single aspect of building that particular scope. It ultimately took me four generations of designing and re-building to get something that would reliable pass an adequate amount of current to power my on-board devices. Maybe I just took a wrong turn or had back luck, but it was enough to convince me to go back to hanging an on-board battery on my subsequent ATM projects.

It reminded me that Occam's Razor (or "keep it simple, stupid") applies to ATM'ing. :S

You can see the sordid details of my various trials towards the bottom of this page of my web site.
http://jimrichberg.com/astronomy/Natasha%20Structure.htm

Jim