Posts Made By: James Barnett

From time to time on Astromart and elsewhere on the web I see eyepiece reviews that say thing like: "...and then I put my [Insert name of your favorite 60 degree+ AFOV eyepiece here] into my Klee barlow, and boy it really knocked my socks off. The [Insert name of your favorite 60 degree+ AFOV eyepiece here] plus barlow combination is great because it gives such a wide field at such high powers."

Wouldn't a barlow like the Klee, Celestron Ultima, Orion Ultrascopic, etc., vignette the light cone in many wider field eyepeices, and thereby reduce throughput, contrast and resolution? I am interested in any rules of thumb, formulae, etc., anyone can provide to help determine whether a given eyepiece-barlow combination is vignetted.

Thanks,

Jim

Okay, well, maybe not a cage match, and not in Texas, but a gentlemanly duel between respected Orthoscopics to settle the score on who's sharper, flatter and more contrasty.

Over the last two nights I've been comparing the University Orthoscopics Abbe Orthoscopic (aka the UO "Volcano Tops") line to other respected or even highly respected Orthoscopics.

The UO 25mm, 18mm, 12.5mm and 7mm were matched up against 0.965" Takahashi Orthoscopic contenders in like focal lengths (25mm, 18mm, 12.5mm, 7mm) as well as matching a Zeiss Jena Abbe Orthoscopic of 10mm focal length against the UO 9mm.

Some of the results were surprising to me, and others reassuring. Reassuring in the sense that when one buys Zeiss one is not wasting one's money, but more on that in a bit.

I focused (bad pun) on comparing these oculars with reference to the hallmark virtues of the Orthoscopic design; sharpness, flatness and contrast. Test subjects included open clusters M35, M44, M67 and M37, and the planet Saturn. The test bed was an excellent Orion 100ED refractor on a driven Celestron AS-GT equatorial mount. I chose this set up over other refractor OTAs and equatorial mounts for a couple of reasons. First, I am astounded by how far the Chinese and Taiwanese optics makers have come in the last few years and feel that increasingly their products represent the best deals in astronomy. Second, the advances in such optics are not going unnoticed. There are ever-growing numbers of amateurs purchasing similar scopes from Orion, William Optics, Stellarvue and other designer/importers. Using optics that are more accessible may make an evaluation more relevant and personal to a larger number of hobbyists.

Without further ado, here are the results:

At each focal length (25mm, 18mm, 12.5mm and 7mm) the UO Volcano Tops and Takahashi Orthos were virtually identical in the categories of sharpness, contrast and flatness. I honestly could not detect one iota of difference between them 99.9% of the time. Each eyepiece showed the same number of stars in the open clusters, and on Saturn, the same surface detail, ring system detail and moons. In fact at 18mm in particular the UO was consistently a teensy bit sharper than its Takahashi peer, and displayed a slight amount less scatter on Saturn.

That surprised me. I had read several other reviews comparing the UO, Takahashi, Zeiss and Pentax SMC Orthos, and uniformly those reviews concluded that the UOs were good, but not a match for the Zeiss and Pentax SMCs, and that the Takahashis were equal (or very nearly the equal) of the Zeiss and Pentax SMCs.

But then entered the "Z" factor. The 10mm Zeiss Jena Ortho trounced its 9mm UO opponent in sharpness and contrast. More cluster stars were visible in the Zeiss than in the UO, despite its lower power (90x vs. 100x for the UO), and more ring (Cassini sharper and blacker) and planetary surface detail (2-3 bands consistently versus 1 consistently) was visible in the Zeiss. The Zeiss "homerun" was in the scatter department. Both the Takahashis and UOs showed extended diffuse glow around Saturn; perhaps extending a planet's width in radius around Saturn. The Zeiss showed only the slightest amount of scatter on Saturn; the diffuse glow extending perhaps only a quarter ring's width radius around the planet. Wow. Heck, make that should be WOW!

I plan on repeating this comparison on the moon to validate these results and concentrate a little more on resolving power, but for now I am becoming convinced that the UO Orthos are a GREAT DEAL! I am now looking for a complete set of Pentax SMCs and a set of UO HDs to do an Orthoscopic Battle Royale.

As you may know from Floyd's earlier "ocularholic" thread, my name is Jim and I too am an ocularholic.

For years the addiction manifested as a penchant for good "value-priced" eyepieces. Plossls, Ultimas, Orthoscopics, etc. During this time I was convinced that there really wasn't any reason to spring for pricier glass. For the price of one Panoptic (the "P" word) I could get three Ultimas afterall, and besides Todd Gross says that Ultimas are one of the best deals in eyepieces.

But as I got older, my tastes matured a bit too. I still loved my Plossls and Ultimas, but re-aquaintance with an old 20mm Meade research Grade Wide Angle (Erfle) tempted me to branch out. It's contrasty 70 degree field of view hinted at the mystic transcendence from merely "looking at" to "going there" promised by the uber-glass. Not a spacewalk, mind you, but rather a window rather than aisle seat. I mean one or two wide angle eyepieces couldn't hurt, right?

Now open to the possibility of more modern, better corrected wide field eyepieces, still that old frugality intruded. I reasoned that one did not need to buy the most expensive wide field eyepieces to get the big picture. Panoptics and NAGLERS (the "N" word) be cursed! So I dabbled. A Meade Super Wide Angle here, and a University Optics MK-70 there. Oh, and an Ultima Wide Angle (later Axiom) thrown into the mix for good measure. A notch or two up the price ladder from my beloved Plossls and Ultimas, but definitely not in the price stratosphere occupied by the dreaded, overrated, marketing invention, the Nagler. I mean, who in their right mind needs 82 degrees? 65-70 degrees is wide enough for any sane individual, right?

But then there was that damned Pentax XL 21mm. I wish I had never laid eyes on her. Sitting there in the store, rainbow multicoatings agleam and build quality like a battleship. I couldn't resist, so I promised myself that I would buy "just one." Just one premium eyepiece. One eyepiece at nearly twice the price of my elite Axioms and Super Wide Angles, and I would be satisfied. Or so I thought.

Then it happened. "Panoptic". There. I said it. I can now say "Panoptic" without even blinking. I bought one. A 2" 27mm Panoptic to be precise. The agony of the small fortune paid to the merchant was replaced the very night of the acquisition with the ecstasy of more nebular detail than I has seen in my life. The little elves at the Televue factories worldwide put a lot of photon-o-philic pixie dust in the multi-coating vats. There's no other rational explanation. The throughput and subtle details visible with the "Fish's Mouth" of M42 centered was pure magic. Panoptic, Panoptic, Panoptic! I am even willing to overlook the less than perfect edge correction at f4.9.

But the Panoptics are so good, never would I want ot need to buy a Nagler. Still, maybe I could dip a toe in the water, so to speak. Those aging Meade Series 4000 Ultra Wide Angles are knock offs of an earlier generation of Uncle Al's Nefarious Naglers. So I bought one. 84 degrees rather than that anemic 82 degrees promised by Televue's priciest creations. I bought a 14mm. Boy is it tall. Heavy too. And looking through it was more like wading in a star-filled pool than looking through a piece of glass. No match for the black-magic coatings on the Panoptic in the contrast and subtle detail department, but W-I-D-E A-N-G-L-E heaven nonetheless. It is one of those "wow" eyepieces. I doesn't matter what aperture you are using or what object you are viewing. Anyone looking through the eyepiece will involuntarily say "wow". Very cool.

Then a few weeks ago it struck me. Maybe I do understand the Nagler after all. Marry the 80+ degree "bowl of night" effect to the supernatural coatings from the Panoptic, shoe horn the result into a physics-defying moderately sized Type 6 package, and you might have something.

So I bought one. A 7mm Type 6. And used it last week for the first time. Simply sublime. A time machine. Galaxies like M51, M104 and M82 screaming "Look at me! Look at my mottling. Leave your averted vision at the door." M3 looking like a well-aimed photon snowball on its way to my front yard. Jupiter giving up belts and festoons aplenty, moon discs, transit shadows. Unbelievable. Saturn's ring system (ring system; not rings mind you) daring you to say "spoke" or "Enkce". And I thought Naglers were for faint DSOs only. P'shah.

I'm not saying chuck your Ultimas, Televue Plossls, Ultrascopics or University Orthos. Nor am I advocating eschewing TMB Monocentrics or Zeiss Orthoscopics in favor of Naglers for the moon and planets. What I am saying is that the Naglers are really, truly amazing. Don't let your skepticism exclude you from the experience as I did for many years.

Okay, with that as background, I have a question. Certain of the older Naglers (*cough* 20mm Type 2 *cough*) are quite collectible and often raved about. Various reviews tout the coatings on the newer Type 5s and 6s as being superior to the coating son the older units, and the better size efficiency of the Type 6 in particular is undeniable. There is no comparison in contrast and throughput between my old Nagler knock off 14mm UWA and my new 7mm Type 6. How do the newer Naglers stack up against the old favorites? Is there any reason other than sentamentality to own the older designs?



- Jim

As the collection of scopes has changed, so too have my "3 most used".

Right now I use the 32mm Televue Plossl, 21mm Pentax XL and 8mm Orion (Vixen) Lanthanum Superwide most often, though a new 7mm Nagler Type 6 is on the verge of challenging the 8mm Lanthanum Superwide.

Regards,

Jim

You might want to consider the tried and true Vixen LVW line. The 13mm in particular would be a nice unit for your stated observing likes. It has a 65 degree flat, well-corrected field of view.

You mentioned light throughput being a concern. I have a 12" f/4.9 Dobsonian and have both a 16mm Konig II and 17mm LVW. The Konig II is a very slight bit brighter but suffers from very short (for a 16mm) eye relief. The LVW has considerably better edge correction making almost all 65 degrees usable, and has very comfortable 20mm eye relief.

I would expect the 13mm LVW and 12mm Konig II to compare similarly.

Regards,

Jim

Hi all, I just picked up a set of Takahashi LEs here on Astromart which are in shipment, and from the photograph I noticed that the 30mm LE is missing the inch-wide knurled rubber grip ring material. From online retailer photos of the 30mm LE, the grip ring should be 10 "squares" or "knobs" wide. I was wondering whether anyone knows how I could get a replacement Takahashi grip ring? Alternately, I would even consider buying an inexpensive eyepiece from another maker just to get a ring that would fit the LE's upper barrel. Any ideas?

Thanks,

Jim

Amateur astronomy has come a long way in the past 3 decades in terms of availability of affordable, quality equipment, but finding objects to view is still a beginner's first big challenge. A night of casual deep sky observing through Scutum, Sagittarius and Scorpius last night using a 4 inch refractor reminded me of a similar summer night 30-odd years ago...

As a child in elementary school space science had always interested me. A like-minded classmate and I each squandered our life savings at the time to purchase department store refractors. His was a 40mm alt-az mounted Japanese refractor. I can't remember the brand, but I do remember him boasting that his optical tube was "longer" than mine, so it must be better. Mine was a 60mm Jason achromat on an alt-az mount. I recall the vivid Sci-Fi-esque artwork on the box, which I carried home from the local department store on the handlebars of my bicycle. I also remember the marketing hype - its key feature was 280x, so the longer tube benefit was rebuffed with the Jason's higher "magnification". Boy were we clueless.

It was our third night in a month sleeping out in the back yard trying to find some real "deep sky" objects with our scopes. While in two prior all-nighters we'd managed to pull in a naked eye Messier, M45, we were frustrated to the point of fits by our inability to locate the esoteric stuff like globulars, planetary nebulae, rich open clusters and the like. In retrospect, the long focal lengths and corresponding narrow fields of view, poor quality eyepieces, and near useless finders were largely to blame, but being young, impatient and new to the hobby, we had high hopes and higher expectations.

I remember the false start we had during the prior observing session. We stumbled on an open cluster near Cygnus that we were certain must be a Messier object, but were disappointed to find no object plotted at that location on our Edmund Maginitude 5 Star Atlas. We were crushed. I was to learn years later that what we'd stumbled on was Brocchi's Cluster (Collinder 399; "The Coathanger") in Vulpecula, but we were after Messier objects and could almost taste our first "discovery". That momentus event (our first "real" Messier discovery) had to wait until our third attempt.

My backyard in those days had great Southern exposure, but our house blocked the Eastern half of the sky. Still the skies were dark and clear and we had a perfectly framed view of the mighty scorpion to the South. Both of us thought we could see something like a faint puff of fog off the back of Scorpius' stinger. Being able to see the object we were hunting in our scopes turned out to be key. It was M7, "Ptolemy's Cluster", of course, and we had a relatively easy time getting our narrow FOV refractors homed in on the target once we knew where to look. Epiphany and celebration! We'd done it.

This discovery also gave us missing "context" for tracking down other Messier objects. The brighter ones would look like faint puffs of cloud with naked eye averted vision. The dimmer similarly looked fog-like in our finder scopes. It was as if the floodgates had openened. Armed with some confidence and experience and most importantly a better idea of scale and context, we located a string of objects in short order - M6 "The Butterfly", M4, M80, etc.

From that night long ago to last night, it occurred to me that the Scorpius-Sagittarius region is rich with deep sky objects. Like fishing in a barrel, the odds of successful object location are many fold higher than similar hunts in less well populated celestial geographies. In fact, I think the Scorpius-Sagittarius beach may be the ideal spot to for beginners to test the waters of Messier's ocean.

All the best,

Jim

One of the nicest refractors in terms of image quality I've ever owned was a Vixen-made, Celestron-branded 102mm f/9.8 achromat, since donated along with an Ultima 2000 8" SCT to the local Junior High School's science department. I think that it was a particularly good example of the Vixen achromat as on a couple of occasions it clearly outperformed other Vixen 102s and at one public outreach event several years ago it actually out-performed (meaning in this case split tight doubles more cleanly and showed more banding detail on Jupiter) an Astro-Physics Traveler. I realize that there are many explanations for its apparently excellent optics ranging from (1) the optics really were good to (2) the other scopes it was compared to had been mishandled, were out of collimation, were dewed up, etc. I like to think the answer was closer to (1) than to (2).

In any event, I have a lingering fondness for Vixen achromats. Coincidentally, recently I stumbled on listings for Antares "Vixen-Spec" achromats on several Candaian sites and on one US site, though the US site appears to no longer offer the 105mm units I would be most interested in. The 105mm units are available in three focal lengths: 1000mm, 1300mm and 1500mm.

Questions, questions, questions:

1. Does anyone on the forum have one of these?
2. If so, how do you like it (optically, mechanically, etc.).
3. Would there me significant difference in suppression of CA between the 1300mm and 1500mm examples of the 105mm?

Thanks in advance for any insights.

- Jim

Hello eyepiece afficionados! I've been trying to finish my research for a new review to be posted on CN and perhaps here. The title for the review is "Ocularis Nostalgica: Meade Research Grade" and the topic is a full line review of the collectible Meade Research Grade eyepieces from the early 1980s. I'm shy about 6 more hours under the stars to finish up the "Wide Angles" (Erfles). Last weekend during the heatwave I managed to get through the Research Grade Orthoscopics using Jupiter and some doubles and DSOs in Hercules, Lyra, Scutum, Sagittarius, Scorpius and Ophiuchus. I have been working half days for the last 3 days, using accrued vacation, to try and finish up but all three nights were ruined by a marine layer that brought in low clouds starting about 9pm. Tonight, however, Clear Sky Clock predicts no cloud cover for me until early morning (3 to 4am), so I expect to wrap up the fun part (observing) tonight and take the photos and do the write up on Sunday and Monday. Just an FYI to keep an eye open for the review.

Regards,

Jim

Just a quick question regarding focusing technique for telescopes using a focuser that moves the primary mirror (i.e., most SCTs and some MCTs).

Is there a particular direction one should move the primary for achieving the final focus?

For example, is there any advantage in achieving critical focus by reaching final focus moving the mirror (with gravity) back toward the rear of the OTA?

Just curious. I have had a couple of SCTs and MCTs over the years and have currently an Orion (Synta) 150mm MCT that use this type of focuser, and never really thought about whether there's an optimal techniche fo focusing these scopes.

Thanks,

Jim