VixenSLV Eyepieces€¦ · 14/05/2014 · ASTRONOMY TECHNOLOGYTODAY...

ASTRONOMYTECHNOLOGY TODAYYour Complete Guide to Astronomical Equipment

Volume 8 • Issue 3May-June 2014 $6.00 US

BAADER MPCC MARK III • TPO 10-INCH IMAGING NEWTFIRST CONTACT POLYMER OPTICS CLEANER • NEAIC AND NEAF 2014

CALCULATING THE PERFECT TELESCOPE SIZE POST PARACORR TYPE-2

Vixen SLVEyepiecesHigh-Quality, Flat-Field

Eyepieces

27 TELE VUEPreviews the “Big” Paracorr

29 SKIES UNLIMITEDCelebrates 10th Anniversary withNew Website

30 SURPLUS SHEDExclusive Rights to Amateur Scientiston CD-ROM

30 OPT10th Annual SCAE - Southern CaliforniaAstronomy Exposition

32 JMI TELESCOPESNightrider Wedge for 8- to11-inch SCTs

33 SKY VISIONDemonstrates Direct Drive Mount

Contributing Writers

10 Astronomy TECHNOLOGY TODAY

ContentsIndustryNews

Gary Parkerson discovered early in his amateur-astronomy career that he was asfascinated by the tools of astronomy as by the amazing celestial objects they reveal –perhaps more so. When not writing about astro-tech, he covers industrial technologyfor a variety of online resources.

Erik Wilcox lives off the grid on the Big Island of Hawaii, and has been observing forover 20 years. When he’s not viewing from his dark backyard sky, he works for a nat-ural foods chain, and spends his spare time hiking, kayaking, snorkeling, and per-forming music.

Austin Grant, a high-school Chemistry and Biology teacher, is a self-described per-petual hobbyist, experienced in such areas as building computers and repairing arcadeequipment. Austin stumbled into astronomy several years ago and it soon became hisprimary interest. Being a child of the digital age, it didn’t take long for him to find dig-ital astro-imaging and he sold his last pinball machine to fund his current imaging rig.Austin shares his passion for stargazing with his students and is in the process ofbuilding a school astronomy club.

David Ellison is a retired anesthesiologist who lives with his patient wife of 27 years, andan old gassy dog. He’s an amateur machinist, an advanced woodworker, and he runs the“Astronomy Hacks” user group on Yahoo. David has a small home observatory inChattanooga, TN, and travels to star parties for dark site imaging. He uses his photo-graphs to introduce younger people to astronomy.

Dave Snay is a retired software engineer living in central Massachusetts. He graduatedfrom Worcester Polytechnic Institute and has been an astronomer and astrophotogra-pher for more than 10 years. David currently pursues fine art photography, specializingin traditional black/white images.

Ryan Goodson is the owner of New Moon Telescopes. He is consumed with all mattersastronomy, particularly public outreach. Ryan is a cofounder of the Central New YorkObservers and Observing. He serves as an officer and on the boards of directors of bothit and the Syracuse Astronomical Society. Ryan is also a 2014 Solar SystemAmbassador and will be involved in several NASA related presentations throughoutCentral NY as one of its representatives.

The perfect telescope size is… It’s aline that invites critique and insight fromevery corner of the astronomical commu-nity. Having built a number of telescopesfor clients all over the U.S., I have calledthree of my New Moon Telescopes myown: a 12.5-inch f/4.9, a 16-inch f/4.5,and a 27-inch f/3.9. Outside of thosethree Dobsonian-style telescopes, I havealso owned various refractors and binoc-ulars and a large arsenal of eyepieces. Butsince I build Dobsonians-style telescopes(okay, “Dobs”) for a living, however, I willlimit my opinion to that particular style.My opinion of the perfect Dob size haschanged over the years as my observinghabits have also evolved.

I use “size” as a catchall to describethe combined effects of aperture andfocal length. There’s a big difference inthe relative size of a 20-inch f/4 versus a20-inch f/5, just as there is a big differ-ence in the sizes of a 15-inch f/5 and a20-inch f/3.75. In the first case, the aper-tures are the same, but an eyepiece in thef/5 is 20 inches farther from the groundwhen viewing near zenith; in the secondcase, the focal lengths are the same, butthe 20-inch has much greater reach andweighs more, all else being equal.

Astronomy TECHNOLOGY TODAY 53

By Ryan Goodson

Image 1 - Despite its considerable aperture, the eyepiece of this 20-inch f/3.3 New MoonTelescope remains within comfortable feet-on-the-ground reach of most observers – evenwhen the Dob is aimed at zenith. Gone are the days of fumbling with ladders in the dark.

Calculating the PerfectTelescope Size

Post Paracorr Type-2And the perfect telescope size is…?

The Basic Formula for My“Perfect-Sized” Dob

For a telescope to qualify as the “per-fect size” for me, it must meet a number ofcriteria:

(1) It must have a well-corrected pri-mary mirror and beautifully-flat second-ary mirror.

(2) The scope must be light enoughfor me to handle and pick up alone, butmassive enough to give a stable image atthe eyepiece, even at the highest powers.

(3)There must be enough aperture togo deep – very deep!

(4) My observing list can be some-what eclectic, so one night I may be view-ing large galaxy clusters and open clusters,requiring a wide field of view, and the nextI will be trying to split close doubles anddoing planetary work, needing highermagnifications.

(5) The primary mirror must notbe so thick and heavy as to take too muchtime to reach ambient temperature.

(6) Balance is also an important piece

of the perfect-scope puzzle. I jump all overthe sky and enjoy using and testing anumber of Paracorr/Barlow/bino/eyepiececombos, so the telescope must be able tohandle large weight changes on the busi-ness end without drifting.

(7) I often take a smallish vehicle tovarious observing sites, so the telescopecannot be moved even partially assembled.The upper cage, truss tubes and mir-ror/rocker box hit the field unassembled,so it is important that I am able to get allpieces out of the van and set up, assem-bled and collimated in less than five min-utes.

(8) And finally, I most enjoy seatedobserving, so I would rather not scurry upand down a ladder if I don’t have to.

Criteria One:Excellent Optics

That first criteria has always been metfor me when I use Lightholder Optics formy primary mirrors and Antares Opticsfor the secondaries. Regardless of focal

ratio, Lightholder Optics has proven tome that I can expect a beautifully cor-rected figure, with a smooth polish and nozoning issues from edge to edge. Since to-ward the edge of the mirror is where mostof the light is being gathered, the edgecannot exhibit any sign of being turneddown or turned up, and no Lightholdermirror we have tested to date has exhib-ited those negative characteristics.

This is not to say that other opticianscannot or do not achieve the same type ofresults, as I am quite sure they do. In fact,I have used various other opticians in thepast, typically with excellent results. Buthaving used Lightholder Optics so often,I have developed a particular fondness andtrust for the firm.

This brings up Antares Optics, whichis located only a couple of hours from myshop, so I get the satisfaction of buyinglocal. They are also willing to provide in-terferometry reports with their secondarymirrors, and the tests have yet to contra-dict anything we have seen at the eyepiece.



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Criteria Two: Light EnoughAs for my second criteria – light

enough to handle, heavy enough forstability – since everyone’s definition ofwhatconstitutes “lightweight” is different whenit comes to astronomy gear, here’s mine: Imust be able tomove the scope about alonewithout exerting much energy. Sincestargazing (other than the close star) isbest done at night, and I also sleep nights;I need all the extra energy I can get –from the beginning of the night to the(sometimes) long trek home. I would rathernot lift anything over 40 pounds if I canhelp it.

Criteria Three:Aperture Matters

Bottom line: aperture matters – a lot!I realize this is subjective and depends on

the type of object one enjoys viewing,but the bigger the mirror is, the happierI am. Larger mirrors can also achievehigher magnifications (subject to seeingconditions, of course) than theirsmaller counterparts, and the more Iobserve, the more I like to push a primary’s

capabilities.

Criteria Four: Wide Enough;Powerful Enough, Too

Criteria four dictates that theperfect-sized telescope will frame theAndromeda galaxy with her two satellite



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galaxies and, with a quick switch of theeyepiece, tease out a globular clusterhidden in her dust ring. Making out sub-tle detail in galaxy clusters is also far eas-ier with the bigger mirrors, so this is animportant deciding factor as well.

Criteria Five:Fast Cool Down

Criteria five demands that the pri-mary mirror must cool to ambient withinhalf an hour of arrival. Fans help toachieve this particular goal, but primariesof more than two inches thickness are outof the question for me!

Criteria Six: Doesn’tRequire Counterweights

I’ll get to this one later. Let’s do cri-teria seven first.

Criteria Seven: LightweightComponents that AssembleQuickly

When going out to observe, I want tospend my time observing, not unloadingand assembling. If the event is a dedicatedtwo-day-plus star party, then that’s a differ-ent story, but those are few and far betweenfor me. My typical night under the starsconsists of a 45-minute, or longer, drive toa dark site (I have dark skies where I live,but I also have a high canopy of trees inevery direction), so quick set up is impera-tive.

After reaching the dark-sky destination,ideally, I am unloaded, set up, and colli-mated within five minutes or less, withoutrequiring breaths so deep that those aroundme need oxygen tanks. After a four or five-hour observing session, I would rather not

start fixating on the pain in the neck break-ing everything down is going to be, so sizealso plays an important role here. As muchas I love viewing through 25-inch and largerscopes, between the sheer size and mass ofthemirror alone,my perfect size telescope isgoing to be a little smaller.

Criteria Eight:Eyepiece Height

For me, a comfortable eyepiece heightis imperative for a Dob to compete for thecoveted perfect-size title. Although I wantto do most of my observing seated, I alsoenjoy public outreach, andwhen the line in-evitably starts to lengthen, standing up be-comes essential. I am 5 foot 7 inches on agood day, so I must be able to view flat-footed when the scope is pointed nearzenith.This is probably the biggest limitingfactor of the size telescope that is going tofit all of my personal criteria.

In the past, this factor wouldnarrow the field down quite a bit. Thankgoodness mirror makers’ capabilities andtesting procedures have also evolved overtime, and thank goodness for the Tele VueParacorr Type-2, too, without which thosemirrormakers would have had no incentiveto produce primaries that are so muchfaster!Without the ParacorrType-2 and theultra-fast revolution it spawned, my criteriawould limit me to 12 or so inches ofaperture.

My Perfect Aperture Is…My perfect-size telescope is not one I

currently or ever have called my own: a 20-inch f/3.3. After building and testing thissize telescope for a client, we quickly ex-panded our current line to include otherlarge-aperture, “flat-footed” telescopes. I amable to view a vast array of DSOs with thisaperture. My personal favorite galaxy clus-ters, planets, or double stars are all wellwithin reach.

Since a 20-inch primary mirror theo-retically reaches to around 17.1magnitude,it packs an admirable punchwhen it comesto going deep, and the rather large 4.5-inchsecondary required at f/3.3 isn’t the contrast


robber onemight think. Close examinationof Jupiter over several nights revealed gen-erous swaths of subtle detail.

Cool down is quickwith an active cool-ing system built into the telescope. Being a“shorty,” using a huge range of ocular com-bos of various weights, including some thatare decidedly heavy, never requires the useof a counterweight system, which satisfiesmy sixth criteria.Of course, a ParacorrType-2 is essential for a fully corrected field, butit’s always nice to have an excuse to purchaseanother Tele Vue product whenever possi-ble.

Gone are the days of needing a ladderfor a 20-inch scope. Keeping your and es-pecially your children’s two feet on theground under a 20-inch f/3.3 is a simpleway for amateur astronomers to keep theirblood pressure down. Couple the 20-inchf/3.3 with an equatorial platform or a drivesystem, and you can even start thinkingabout astrophotography with a big Dob! I

could not be happier with this size of tele-scope. Now, if I can only talk my wife intoadding another “child” to the mix.

Quantifying the ParacorrType-2 at f/3.3

To confirm the critical importance ofthe Paracorr Type-2 at very fast focal ratios,Damian Allis, Steve Capp and I tested arange of eyepieces in the 20-inch f/3.3 onNovember 29, 2013, from17:00- to 22:00-Eastern Standard Time (22:00 to 03:00GMT), with and without the Type-2. Welet the big primary cool for a full hour priorto testing to ensure that it had reached am-bient temperature, which ranged from8- to13-degrees Fahrenheit (-13.3- to -10.6-degrees Celsius). Seeing was roughly 6/10,and we rated transparency at 7/10.

Using aTele Vue 31-mmNagler with-out the Paracorr Type-2, I detected comabeyond the central 40 percent of the field ofview (FOV), while Steve and Damian de-

tected it at 50 percent. With the Type-2,Damian and I found no evidence of comaor other aberrations within the central 90percent of the FOV, but noted that eyeplacement played a large role inwhether wecould detect any coma. Steve found thingsto be perfect for the central 95 percent ofthe field.

Using aTele Vue 22-mmPanoptic, theresults were even worse sans the ParacorrType-2. Damian and I detected coma be-yond the central 30 percent and Steve be-yond 35 percent.With theType-2, I judgedthe central 95 percent FOV to be perfect,while Damian and Steve thought the entirefield showed no aberrations whatsoever.

Using anExplore Scientific 14-mm82-degree eyepiece, our results varied fromthose with the Panoptic only in thatDamian and I switch roles in finding 95-versus 100-percent perfection.

Using a 9-mm Type-1 Nagler, Stevejudged the middle 40 percent perfect with-


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out the Paracorr, and I the central 45 per-cent. With the Type-2 Paracorr installed,Steve thought the entire field was perfect,and I agreed as to the middle 95 percent.Damian didn’t evaluate these combinations.

Next up was a 10-mmDelos where weall thought the middle 50 percent was per-fect sans the ParacorrType-2, and only Stevethought the entire field was less than perfectwith theType-2, rating it at 95 percent, in-stead.

With a 4.5-mm Delos, things took adramatic turn: Steve and I rated the perfectfield at 90 percent sans Paracorr, andDamian at 95 percent. Of course, we allfound perfection from edge to edgewith theType-2 Paracorr installed.

To shake things up a bit more, wetested a 40-mm Konig, with and withoutthe Paracorr.Without theType-2, Steve andI rated the perfect field at 25 percent, andDamian at just 20 percent.With theType-2, I rated the perfect field at 85 percent, andSteve andDamian at 90 percent. Eye place-ment again played a large role.

I was shocked when we actually meas-ured the FOVs and noted the coma-freeareas. If you were to average all eyepieces, Iwould say around 40 percent of the fieldwas coma-free field to our eyes withoutParacorr 2. With the Paracorr 2, our ob-serving eyes enjoyed pinpoint stars almostfrom edge to edge, or indeed from edge toedge. The extra magnification that accom-panies theType-2was barely noticeable, andthe “crispness” of the stars made the imageappear brighter.

Another surprise was the Delos 4.5-mm,whichwas almost as goodwithout theParacorr 2 as it was with it! I’m still trying tofigure that one out, but whenAlNagler andPaul Dellechiaie are the designers, opticalwizardry is the rule rather than the excep-tion.

Unfortunately, Jupiter was too low onthe horizon, and the below-freezing tem-perature made testing (and waiting forJupiter to rise higher) unappealing after afew hours!We easily split Epsilon Lyrae, theDouble-Double, butmost coma testingwas

done on the double cluster because of thecoloring of the stars and the large field theyrequire. I find it to be the most demandingcluster for eyepieces.With the 31-mmNa-gler and the 40-mm Konig, M31 and hertwo satellite galaxies fit easily in a single fieldof view.M33 clearly showed her spiral struc-ture and hydrogen knots. Seeing wasn’tgood enough tomake out the central star intheRingNebula.Damian noted that hewasamazed at the subtle coloring detail shownin star clusters. All three of us agreed thatthe scope holds a superb optic.

To sum up, the original Paracorr revo-lutionized practicality of big Dobsonians,with 16- to 18-inch f/4.5 to f/5.0 Dobs be-coming commonplace, albeit still requiringshort ladders for viewing at zenith by some.The Paracorr Type-2 takes things to ultra-fast extremes considered impractical just afew years ago.

The perfect-size Dob? For me, itsaperture got much, much larger thanksto the Paracorr Type-2, and I couldn’t behappier!



I traveled to NEAIC and NEAF alonelast year - manned its exhibits alone, too,vowing to never do that again. So this yearthere were four of us: Associate EditorsAustin Grant and Chad Patterson made thetrip, along with our newest ContributingWriter, Stan Westmoreland. It was Stan’sfirst trip to these big events, so we saw littleof him during show hours. Given all therewas to see and do, who can blame him?

I’ve no idea how to best measure therelative success of each new edition of

NEAIC and NEAF. Is it quantity or quality,or both? What I do know is that I had agreat time and am, once again, very glad tohave invested the time and energy. HavingStan, Chad and Austin along to assist…Oh, who am I kidding? They did all thehard work – I assisted them. Anyway,making the trip with them made itespecially enjoyable, and I hope they eachmake the journey next year. Thanks, guys!

All of the following photos were takenby either Stan or Austin, many with the

same Canon 60Da that Austin used intesting the TPO Imaging Newt and BaaderMPCC Mark III that he reports on in thisissue. We arrived home with more than athousand good images and hundredsof great ones, so there’s too little room inthese pages for even the really great ones.What follows, in no particular order, aresome of my favorites. You can see over 100images with descriptions in the onlineversion of this issue, though. Hope youenjoy them!


By Gary Parkerson

What’s the first group photo any self-re-specting group of astro-gearheads wouldwant taken at NEAIC? Surrounding one ofthe great mounts and scopes displayedthere, right? Not these guys. From left toright: Stan Westmoreland, Austin Grant, AlNagler and Chad Patterson.

Celestron CEO Dave Anderson addressesthe hundreds assembled for Celestron’s Fri-day-evening product-launch reception.

Astro-Physics’ Roland and Marg Christen atNEAIC.

Steve Chambers and Rui Tripa of AtikCameras at NEAIC.

Software Bisque President Stephen Bisquewas joined at NEAIC and NEAF 2014 by hisdaughter Sarah Bisque, a production engi-neer with the company.

The Gang Was All ThereNEAIC and NEAF 2014

We captured the Chroma team during en-joying the lull NEAIC exhibitors experienceeach hour when its seminars are back insession.

NEAIC AND NEAF 2014

The marriage of William Optics refractorsand iOptron mounts makes for some stun-ning rigs. This shot was taken Saturdaymorning at NEAF before the hall opened toguests.

Howie Glatter setting up at NEAF.

APM’s Marcus Ludes confirming the opticalexcellence of Lunt Engineering’s new 100-mm ED-Apo binoculars. I had a chance totest a sample under clear skies recentlyand, yes, they’re indeed excellent.

An Avalon M-Zero carrying a 6-inch Astro-Tech R-C and a little 50-mm Apo. Yes, theM-Zero accommodates dual saddles. Oneof ATT’s contributing writers currently hasthe M-Zero in hand, and his report shouldbe filed within the next few issues … im-aging conditions permitting.

New Moon Telescopes’ Ryan Goodson hascontributed an article to this issue of ATTthat provides thoughtful insight into the sig-nificance of Tele Vue’s Paracorr Type 2 tothe makers and users of modern premiumDobsonians. He and wife Heather areamong my favorite examples of the familyenterprises that are essential to this uniqueindustry.

All the pretty Vixens lined up in a row, in-cluding some new products mentioned inthe news sections of this issue.

Brian Deis, President of Vixen Optics,shows off a drive component of the Vixenmodular “Transformer” mount previewed atNEAF 2014. I don’t know that he could havemore proud had it been a baby boy.

Yes, Explore Scientific’s eyepieces aredrool-worthy, but so are its refractors.


VixenSLV Eyepieces€¦ · 14/05/2014 · ASTRONOMY TECHNOLOGYTODAY...

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