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Excelsis Ratings/Reviews - William Optics ZenithStarHome[Click Here to Login]Don't have a login? Register!Checking Your TelescopeStarting out in AmateurAstronomyHow to use This SiteWhy Register?[Get rid of the ads!]Voting GuideTurn Left at OrionGuy ConsolmagnoNew $16.37!Used $7.30!Sky & Telescope'sPocket...Roger W. SinnottNew $12.97!Celestial SamplerSue FrenchNew $15.72!Used $15.59!The BackyardAstronomer'...Terence DickinsonNew $31.47!Used $24.35!Ratings:Top:Astronomy:Equipment Reviews:TelescopeReviews:William Optics ZenithStarInfo Votes Messages MoreStatsWilliam Optics ZenithStarBrand andModel:William Optics ZenithStarPrice($USD):$399.00Type: Achromatic RefractorAttributes: Go-To PECUp One LevelAperture: 80mmf Ratio: f/6Focal Length: 480mmFinder:ElectricPower:Mount:Tripod:Weight (lbs): 5.3DimensionsTube Length 15.0" (380 mm)(w/h/d):Description: Objective Type Doublet Element Design / Multi-CoatedDewshield RetractableFocuser 2" Crayford Focuser80 mm Focuser Travel Length360° Rotatable Design1.25" Adapter Brass Compression RingsField Stops 15 BafflesTube Weight Stylish carryingbag Dimensions 48 x 28 x 16cm (WxHxD)(WaterResistance)6x30 erecting finderscopepower Sharp up to 100x (recommended)surface Black Gloss Anodizing / Golden Rims,knobs & Capothers Perfect grab-and-go scopeL- type L- bracket basedNational Audubonhttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (1 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarSociety...Mark R. ChartrandNew $12.97!Used $2.70!The Night Sky 30?-40?David S. ChandlerNew $8.47!(Prices may change)Privacy InformationVote HighlightsZenithstar 80 Review: Part 1Add votes to yourown site:Overview:The Zenithstar 80 (ZS80) has a beautifulappearance. It is well constructed, bothoptically and mechanically. Customer care andservice by its manufacturer/assembler isexcellent. The visual performance is good, butawaits further testing to prove if it is on a parwith Short Tube 80s (ST80s), superior to ST80s oreven comparable to similar focal lengthapochromatic refractors.Tom Trusock and Fred Hissink have providedexcellent reviews of the ZS80. They do a fine jobof reviewing mechanical particulars of thissystem, most of which will not be repeated here.These reviews can be found at www.cloudynights.comEquipment Reviewed:- ZS80 OTA; metal lens cap, eyepiece end cap,soft case- AZ3 mount/tripod (altazimuth)- Red dot Finder 2- 35mm Ultima, UO Orthos 12.5 and 7mm, 2X ShortyBarlow (Orion), extension tube- Filters: Neb1(Sirius) and OIII(Lumicon), V-Block(Orion), planetary(Celestron/Meade)Observing Site:A thirteen acre vacant lot, shielded fromstreetlights and house lights, within a city of aquarter million persons and within 2 miles ofmuch of the retail of that city and less than amile from a high school football field and a citypark with multiple playing fields lit at night.On the best of nights, in the dark hours justbefore dawn, the faintest visible stars at thezenith approach magnitude 5. Magnitude 4.5 skiesare common.Received Condition:The OTA comes sufficiently and attractivelypacked. The scope, wrapped neatly in clearplastic, lies snug in its foam enclosed softhttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (2 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarpack. The soft pack is beautiful as well,sporting thin inch long metallic grabbers chainedto the zipper on the pack. The pack is doubledboxed in attractive well-made boxes. Theretractable dew cap slides smoothly with justenough resistance. The Crayford focuser is verynice in its mechanical operation. The rotatingcell that contains the focuser is a bit stiff.However, I never use it as both the 2-1.5 adaptorand the 1.5 eyepiece/diagonal holder have nicelymade brass retaining/tightening rings that allowsmooth full circular motion. The entire OTA isattractive; jet-black with highlights of gold.The paint finish is nicely done. All screws andbolts are silver in color and substantial.The optical train revealed a noticeable lack ofcollimation. High magnification views of brightstars gave the appearance of an airy disk withmultiple diffraction rings 2/3rds of the wayaround the airy disk and no rings on the otherthird. The appearance was nearly identical towhat can be seen by inputting a coma error of .2to .35 on Cor Berrovoet’s aberrator program.The lack of proper collimation was noticedimmediately upon receipt. Attempts by me toidentify the source of collimation error and toattempt a correction led me to discover thebaffling system used on these scopes. Reading TomTrusock’s review revealed to me that the baffleon my scope was the original inadequate one. WithTom’s instructions I discovered that theeffective aperture of the scope was 71mm, plus orminus 3mm.Tom Trusock’s review highlighted both of thesedefects back in May of 2005. My ZS80, with thesesame defects, was sold as new two months afterthat review. These two defects need to beconsidered separately.It seems to me that a ZS80 sold as new with adefective baffle, two months or more after TomTrusock’s review, should not have happened. Therehad been sufficient time for dealer andmanufacturer to ascertain that the defectivelybaffled systems had been removed from the retailstream or repaired. However, this may have beenthe only unit with a defective baffle thatslipped through the review process. It needs behttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (3 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarsaid that the manufacturer was willing to send areplacement immediately and that the dealer infact did send a replacement baffle at no chargefor the baffle or its shipping.The collimation error is not desireable. It isnot aesthetically pleasing when looking at closebright double stars such as Castor. However, inareas other than double star observations, aquite noticeable collimation error might notdetract from the visual performance of the scope.Further, even with this collimation error, thescope performed up to the advertising claims ofWilliam Optics as a well color corrected achromatallowing useable magnifications of 100X. In lightof this, it seemed to me that I did not have aright to demand replacement/correction as thescope performed according to advertisedexpectations. However, the dealer was solicitousof my satisfaction and secured from themanufacturer the right to return it for repair orreplacement; even though I told them it didperform to the advertised expectations. In lightof the scope performing to the advertisedstandards, I asked the manufacturer if they wouldallow me to test my scope for six months andthen, if I was still not satisfied, to availmyself of their offer to ship the scope free ofcharge for repair or replacement. To this, theyquickly agreed.Finally, it needs to be said that the intra andextra focal images are very similar. This is agood sign. To the best of my memory thesimilarity of these images was superior to an enduserimproved ST80, an Orion F6 100mm, an APM100mm Triplet achromat and perhaps better than anED80.Visual Performance Before End-User Repairs:For about two months I used the scope with thecollimation error noted above and without knowingthat the scope had an effective aperture ofaround 71mm. Under the sky conditions outlinedabove, I was able to see a 12.3 magnitude star inthe vicinity of SS Cygni. The companion ofPolaris and the four components of epsilon Lyraewere visible at 38X. I was able to detect thecompanion of epsilon Bootis by means of ahttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (4 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarbrightening on the first diffraction ring at thecorrect position. However, I was not able toresolve zeta Herculi or delta Cygni. With avertedvision, M13 showed stars at the fringes. And,with an OIII filter, I was able to detect both ofthe main parts of the Veil Nebula and the NorthAmerican Nebula as well. Albireo was beautiful at38X with a 12.5mm UO ortho. Finally, as to thechromatic aberration; the ZS80 does not removecolor nearly as well as an ED80 (Orion’s 80mm EDF7.5). However, it is better than the F5 ST80,the F5 100mm APM triplet and about equal with theOrion F6 100mm refractor.Wide field views with a good eyepiece such as aCelestron Ultima 35X are just exquisite,combining a sharp wide field with the distinctsharp edge of the field stop. Also, nothing shortof spectacular are views with a 12.5 UO ortho,without and with a Barlow. Views are crisp andsharp and snap into focus.Even with the two defects, this is a wellperforming 80mm short tube refractor. Combinedwith its exquisite cosmetic appearance and welldesignedmechanical features, I am comfortablesaying it is worth the full price asked.End-User Repairs:Due to being told that an end user could noteffect repair due to the cemented doublet, andknowing that an attempted repair by the end usermight negate the warranty offer, I had used thescope with the noticeable collimation error for acouple months. However, once I decided that Iwould probably not return the scope to themanufacturer for collimation correction as it metthe advertised standards, I chose to take the OTAapart and see what could be done about thecollimation error.I discovered that this scope is so well designedthat disassembly is easy. One looses the outerretaining ring on the dew cap, slides the capback down the OTA revealing the felt lined edgeof the objective lens cell. Then, one unscrewsthe lens cell from the OTA. Once loose, I thenrealized that the baffle was attached to theobjective lens cell. I also discovered that thisbaffle could be unscrewed from the lens cell thushttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (5 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarallowing the objective lens to be lifted from theobjective cell. Using non-cosmetically treatedtissue paper, I removed the objective from thecell and discovered a one to two millimeterflange or lip on which the cemented objectiverested. At one spot on this lip I placed a shimmade of a piece of index card one millimeter wideand three to four millimeters long. Then Ireplaced the objective and screwed on the baffle.I reinserted the cell into the OTA and thenproceeded to star test. The effect was noticeableand positive. There was noticeably less flaringon the one side and the multiple rings had beendecreased in brightness if not in number. I thendisassembled the dew shield and rotated the lenscell a bit over 1/2 turn counter-clockwise(loosening the cell) on the theory that differentpositioning on the objective cell on its screwmight effect another slight correction to theoverall collimation of the system. The effectwas, again noticeable and positive; improving onthe previous improved result. On bright starshighly magnified the diffraction ring totallyencircled the airy disk. The diffraction ring wasbrighter on about 2/3rds of the ring. The otherthird of the ring was fainter and slightly red.At magnifications of 140X and above the airy diskwas slightly elongated. There were also slightindications of very faint notches in thediffraction ring indicative of a bit of pinchingor astigmatism. My best guess is that theretaining ring of the baffle pressed against theobjective, now elevated at one point by the shim,created a slight amount of pinch.As stated before, it was during this process thatI discovered that the inadequate baffle had beeninstalled. After placing emails and calls to thedealer and manufacturer, I received a new bafflewithin five days of the first email. Havingbecome familiar with the objective lens cell andbaffle system, replacing the baffle was an easyaffair.Visual Performance After End-User Repairs:The improvement of visual performance, though notgreat, has been noticeable. Before, I had tostare and sometimes use averted vision to detecthttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (6 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarPolaris companion at 38X, 68X and 120X. Now,Polaris is easily visible with direct vision atboth 38X and 68X. Also, on extended objects likethe moon, planets and terrestrial objects itseemed that the sharpness visible before at 100Xwas now apparent at 120X and 140X. The appearanceof detail on Mars was improved by tiny bits witheach step of magnification increase from 68X to80X to 100X to 120X to 140X to 175X. On the moon,though no new detail could be seen above 120X,details on the terminator retained a decentcontrast even up to 400X. Color correction isabout the same. Though there is no significantchange, there may be a bit more color present; alittle more purple during the daytime, a littlemore red on Mars, a tiny violet edge on the moon.To Be Continued:On a scale of 0 (poor) to 10 (excellent), theattractiveness of this scope is a 10, themechanical functionality is a 10 and the price isa 10. The visual performance was a 7 and is now,an 8. Whether or not it is a 9 will depend on thescopes performance over the next few months onSaturn, the Trapezium and rima Birt.The optics deserves a solid seven for thesimilarity of the intra/extra focal patterns andfor the excellent baffle. There is pleasantlylittle stray light that enters the opticalstream. Whether or not the end-user collimationrepair will prove beneficial will need to stillbe proven. There are three indicators though thatwill indicate that this is an all around superiorsystem: visual detection of rima Birt, a clearand often visible Cassini division and finally,the visual detection of star “e” in theTrapezium. Once I have sufficiently looked forthese objects I will write up Part 2 of thisreport.Overall Rating: 9Optics:8 Ease of Use:10 Value:10Weight: 5 (Veritable Vote)Date: 09/11/2005 09:38:38 pm GMTBy: Anonymous (xxx.xxx.223.10)Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=454954http://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (7 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarReply Replies: 1I bought the zenithstar to replace my belovedOrion shortube. Mechanically and esthetically itis an easy 10. However, I had another experiencewith the optics. Star tests showed severeastigmatism, I'd say worse than 1/2 wave. Icouldn't even focus to a decent airy disk. I sentit back and eventually, after much back and forthcorrespondence, got the objective replaced alongwith a new baffle. The lens was better, but stillshowed astigmatism and SA to about 1/4 wave. Istill enjoy the scope, it gives breathtakingviews of the milky way and is a pleasure to use,but the astigmatism is annoying. The colorcorrection is above average for an achromat, andlow power views of the moon and planets arepleasing. William optics explanation to me aboutthe optical quality is that I shouldn't expect itto work like a an apo. I don't, but I expected abetter star test than my $100.0 shortube. CaveatEmptor!Overall Rating: 8Optics:6 Ease of Use:10 Value:10Weight: 1 (Unreliable Vote)Date: 01/01/2006 08:49:32 pm GMTBy: Anonymous (xxx.xxx.153.57)Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=481681Reply Replies: 0Click here to see all votes (5 total)Recent Messageshttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (8 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarSubject: Re: vote by xxx.xxx.223.10By: Anonymous (xxx.xxx.223.10)In Reply to: Anonymous (xxx.xxx.223.10) (Original Vote)Date: 10/16/2005 06:52:41 pm GMTZenithstar 80 Review: Part 2Summary of Previous Report:This telescope is excellent in terms ofmechanical functionality and cosmetic appearance.It’s visual performance is good. The quality ofthe optical components and the optical system isvery good. As received, this scope matches orslightly exceeds its advertised performance. Itgives superb crisp views with a snappy focus upto 100 to 120X (30 to 40X per inch of aperture).Customer service by William-Optics is excellentand always a pleasant experience. For example,though William-Optics was under no obligation todo so since my scope matched advertisedperformance expectations, the manufacturer waswilling to check, fix or replace the objectivefor no charge and assume the cost of shipping.Later, when I lost the screw that tightens theCrayford focuser, William-Optics offered to sendme a replacement free of charge.As received, my scope contained two optical pathdefects. First, mis-collimation resulted inslightly less than diffraction-limitedinstrument. Second, the installation of anincorrectly designed baffle cone resulted in asignificant loss of effective aperture. Due tomatching advertised performance parameters anddue to the support of William-Optics and theseller, I chose to attempt an end-userimprovement of the collimation. Disassembly ofthe optical components allowed me to analyze thebaffle-cone. Comparison of the baffle-cone withthe description given in Tom Trusock’s articlerevealed the presence of a baffle-cone designflaw.The end-user is able to perform some improvementof less than optimal collimation. These end-userimprovements are made possible due to the simpleand excellent design of this instrument. I needhttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (9 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarto credit Jeff Barbour for facilitating mycomfort of disassembling optical systems. Havingperformed the end-user improvement described inthe first report, I am satisfied that this scopeexceeds diffraction limited performance. There isno astigmatism. Color correction is better than awell collimated and planarised (thanks go to Jefffor teaching me how to do this) ST80 but not asgood as an ED80. The intra-extra focal images arebeautifully similar. Images of third and secondmagnitude stars at 140X do show images indicativeof about a total 1/5 waverfront error (.15wavefront error of coma and .1 waverfront errorin pinch). The improved collimation resulted inreducing multiple diffraction arcs on one sideand a single faint arc on the other to a singlering. This improvement accomplished incollimation was offset to a degree by the singlediffraction ring being slightly green on thebrighter side and slightly red on the fainterside. The overall improvement allows superb viewswith a snappy focus up to 140X (45X per inch) andcrisp views in steady seeing up to 190X (60X perinch).The second defect with my scope was that itcontained the original baffle cone that cut offsome 10mm of its 80mm of aperture. The purchaserneeds to check to make sure that the purchasedunit contains the new baffle that allows full useof all 80mm of aperture. This check can be doneby following directions readily provided byWilliam-Optics. However, now that it is some sixmonths since Tom Trusock’s review of thisproblem, the purchaser has every reason to expectthe seller to ascertain that the correct baffleis in place. In my case, the seller willingly andquickly without charge shipped a replacementbaffle when informed that I was aware of thisdefect.Second Visual Assessment:This scope provides a visual performance superiorto an optimally collimated and planarised ST80;though not as good as a properly collimated ED80.Visual results in steady seeing include thehttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (10 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarfollowing:- Using an Agena-AstroProducts 70mm Baader solarfilter (a well designed and attractive filterthat cosmetically complements this scope), ricegrain is easily seen.- Rima Birt is visible, but barely so, withdirect vision. (The moon was two days pastsunrise on Rima Birt and at an elevation of 30degrees above the horizon.-Two craters are seen within Plato.- The Cassini division is easily visible withdirection vision, but not dark-pencil-sharp. (45degree elevation, with a full moon, in a steadybut not perfectly steady sky, with a less thanoptimal ring orientation)- Trapezium e is not seen.- Resolved and visible as separate components arealpha Piscium and Epsilon Arietis. Both are atthe resolution limit of an 80mm scope (1.46 arcseconds). According to 33-doubles, the difficultyindex (DI) factor of alpha Piscium is 84.1.According to this scale, a superb 4 inchinstrument is needed to see doubles with a DI of85 to 90.The optical performance of this scope is notmagical. But it is good for an 80mm aperture andvery good for an F6 80mm achromat.A Comparison:I am not a professional astronomer. I am not evena serious amateur. Though in the view of thosewho have no interest in astronomy or telescopesmy fascination may seem obsessive, compared tomost of the persons who read reviews such as thisI am a leisurely scopist and stargazer and havebeen so for over forty years. I feel it isunreasonable for me to expect perfection from anyoptical instrument. In the words of my mother-inlaw,one needs to be satisfied with less than thewhole pie. Smart person, she. In a similar vein,I feel that amateur telescopes of today (with theexception of the ubiquitous department storetelescope) are much like modern automobiles,there really aren’t any bad models, thoughindividual examples may be lacking.http://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (11 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarIn light of the foregoing inexpert opinion Ipreface the following by saying that all of thefollowing have been good satisfying performers. Ihave learned much about telescopes and a bitabout astronomy from the use of each. Theseinclude the Orion Short Tube 80 (ST80), the OrionED80 (ED80), the AstroRubinar100 (AR100), theETX90 (ETX90), the 100mm APM Triplet-Achromat(TA100), the Celestron C90 (C90) and theZenithstar 80 (ZS80). In each of the followingcategories, my rating goes from pleasing (good)to wow! (very good).Visual Performance (crisp, good detail, snappyfocus):- C90, ST80- AR100, TA100, ZS80- ETX90, ED80Aesthetic Appeal (cosmetics-looking at the scope):- AR100, ST80, C90- TA100, ED80- ETX90, ZS80Mechanical Functionality:- ST80, C90- AR100, TA100, ETX90, ED90- ZS80Aesthetic Appeal (looking through the scope):- C90, ST80, AR100, TA100- ETX90- ED80, ZS80Portability and Ease of Use:- AR100- ETX90, ED80, TA100- C90, ST80, ZS80A Third Assessment:This second visual assessment was performed overa series of nights in good but not superb seeingconditions. I am sufficiently pleased with theperformance of the ZS80 that I will not beavailing myself of the offer by William-Optics tocorrect or replace the optics. The performance ishttp://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (12 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarsatisfying. The Zenithstar 80 now exceedsadvertised performance expectations. In light ofthe latter, asking William-Optics to repair orreplace the optics without charge would be unjust.As I have not yet used the scope under superbseeing conditions, I feel that there is areasonable chance that the ZS80’s visualperformance will more nearly approach that of theED80/TA100 in terms of crisp detail. Inparticular, giving a sharp rendition of Cassiniand Rima Birt, and a glimpse of Trapezium e.Should an experience of such seeing provide theseresults, I will offer up a third assessment.ReplyPost Un-related MessageSubject: Great Little ScopeBy: Anonymous (xxx.xxx.63.253)Date: 01/27/2005 08:00:05 pm GMTI have the ZenithStar 80mm. It is simply a joy touse. The rotatable focuser makes it really easyto scan and pan. It has some false color. Verymild purple fringing around the edge of the moon,but not worth using an MV filter. Your better ofwith a variable polorizing filter that Orion hason sale.Very high contrast with this scope up to 100x asit states on the WO website. Saturn is OK throughit and the most moons that I have seen off and onwere 4 or 5. All and all not a scope that I wouldchoose if I was just viewing the planets.The wide field views are amazing? Peiades looksterrific! Its very easy to spot open clusters,such as M37 & M36.I have never looked through a SV Nighthawk, butI'm sure that the views would be simular.The travel case that comes with the scope isgreat. Room for 1 2" EP, 3 1.25" EPs, and otheraccesories.http://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (13 of 14)2006/4/26 下 午 12:09:20

Excelsis Ratings/Reviews - William Optics ZenithStarReplyPost Un-related MessageClick here to see all messages (2 total)©2004 by Excelsis Consulting. All Rights Reserved. E-mail webmaster to report abuse, problems, orcomments.http://www.excelsis.com/1.0/entry.php?sectionid=12&entryid=572 (14 of 14)2006/4/26 下 午 12:09:20