Harry Siebert 2" 36mm Observatory Class

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Harry Siebert 2" 36mm Observatory Class
In search of a 2-inch wide-field EP in the 30-35mm range for my 17.5-inch f/5 truss scope, i called Harry to see if he could help (the megabuck megaweight jobs are not a consideration for me)
On his advice I decided to purchase one of the new Siebert 36mm Observatory EP's. This EP looks good, weighs well under one pound, has an approx 1.5-inch eye lens, a set-screw recess, and comes in one of Harry's neat belt-pouches. It also has Harry's incredible internal blackening - man it is *black*, way more so than my TV/UO/Celestron EP's.
He also supplied a press-fit eyecup to keep eyelash crud off the eye-lens - not sure if this comes standard.

Performance-wise i am very pleased - this eyepiece is a keeper. Stars are in focus across the field (70deg I think), it is not fussy regarding eye-position, and has good eye-relief without blackout. It is very easy to focus, unlike some EP's which require the focus to be 'spot on'. At f/5 it performs way better than my UO 32mm Koenig (too much black-out, too fussy re eye-position, and too many seagulls). It is also more user-friendly than my 40mm Axiom, due to smaller size and less out-travel.
In all this looks like being a great general purpose EP for a big f/5 scope.

I do not have any 2-inch Nagler/Panoptics to A-B it with, but based on reviews and comments i have seen on the web i have no reason to believe they would perform noticably better than the Siebert.
As a combination of fine performance and reasonable price i give this baby a 10.

Bob Bennett, Maple Vly WA

Overall Rating: 10
Optics:10 Value:10
Weight: 12 (Trustworthy Vote)
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=160859 

fussy re eye-position, and too many seagulls). It is also more user-friendly than my 40mm Axiom, due to smaller size and less out-travel.

How does the sharpness/brightness/contrast/color compare to the Axiom?
Harry Siebert 2" 36mm Observatory Class
I bought the Siebert 36mm Observatory Class eyepiece to be used in conjunction with my Celestron 9.25 SCT, which is equipped with the wonderful new 2" William Optics Diagonal. In fairness, I’ve only been observing for the past four years. My other eyepieces consist of a new Siebert 13mm Ultra EP (reviewed elsewhere), and Orion Sirius 25mm and 10mm plössls which came stock with an AstroView 120 achromatic refractor. I haven’t looked through too many EPs, so I don’t want to give anyone the impression that I have experience comparing mid to high price eyepieces.

I’ll start with the things I don’t like about the eyepiece. For starters, it comes in a bubble wrap baggie, which for $200 is pretty lame. Second, the removable eyecup has an annoying tendency of falling out; this is more of a peeve than a problem though, especially since it’s supposed to be removable. The primary shortcoming of the eyepiece involves the upper lens element retention ring. Upon initial inspection, the retention ring appeared to have been colored in with black magic marker. After less than a month, the marker coloring started to wear off, revealing the original white underlying color or the retention ring. I ended up wiping off the balance of the marker because it was messy and still came off sporadically. The marker coloring looks incredibly cheap and smacks of cutting corners. I'm curious to know if anyone else has noticed this, or whether this was a fluke with my EP due to Harry’s production back log. At any rate, the exposed portions of the retention ring are now white - hardly something you want in the optical path. However, with the eyecup in place, the light path is insulated from any potential problems. In fairness, I couldn’t detect any loss of contrast or detail resulting from the white retention ring with the eyecup removed.

Now for the good news. The eyepiece has an industrial-look finish, which I happen to like. The turned metal barrel has the eyepiece size stamped in the side, is threaded for 2” filters, and is capped with a textured black ring into which the upper element retaining ring is inserted. While the machine-turned look might not appeal to everybody, it certainly affords an excellent grip. A real surprise about the EP’s construction is that it is both solid and very light. The optical glass is terrific, although coatings appear to have been used sparingly. Per Harry’s website, this appears to be based on the lens manufacturer’s recommendation for optimized light throughput.

I have used the 36mm EP over the course of several nights; the observing conditions varied between 7-9.5 out of 10. As previously mentioned, my basis for comparison is limited. However, after learning the idiosyncrasies of the Siebert 36mm Observatory EP, my impression is that optically it appears to be very good, if not excellent; the eyepiece performs wonderfully. Using my telescope at f/10, stars focus very tightly and are sharp over almost the full field, softening only at the extreme outer edge - roughly the final 3-5% of the field. This degradation was not objectionable at all, and you don’t notice it unless your looking for it. Although there is no image blackout at all at f/10, you have to keep your eye almost directly on-axis to avoid flaring on brighter stars. A quick word on the apparent field of view - it is BIG. I was able to just fit the double cluster into the field of view; the view was incredible. The contrast on DS objects was great; it blew the 25mm plössl out of the water despite the wider field of view and lower magnification. The Ring Nebula was fantastic. The wide field of view also makes star hopping a breeze when used in conjunction with the finder scope.

Happily, I was able to bring the eyepiece to focus with a Celestron f/6.3 focal reducer in place. I should note that my setup includes a TeleVue 3” thread-on extension tube to accommodate my non-threaded 2” diagonal, so the eyepiece is situated further back than it would with a standard SCT diagonal in place. At a focal length 36mm and with the focal reducer in place, the C9.25 optical train is pushed to its low power limit. Again, stars were tight across the field, but eye position became more critical, as it became prone to blacking out. I believe that this a function of the SCT and focal reducer, as this eyepiece is designed for fast telescopes.

I should note that the 36mm Observatory EP appears to be somewhat sensitive to external influences. The top lens element is large, and is prone to pickup unwanted reflections from external light sources. I had initially thought that the resultant glare was from internal reflections, but after extensive use under a variety of conditions I concluded that stray lighting was the culprit. Use of the eye cup definitely helps, as does the avoidance of any extraneous neighborhood lighting. Views of the Moon and Mars at its current opposition showed no glare, internal reflections or flaring. In addition, they were both wonderfully detailed; I didn’t notice any false color. The Martian polar cap and substantial surface shading were easily discernable.

After using this eyepiece, I have to conclude that it is indeed something very special. At approximately $200, you get approximately the same true field of view as the 31mm Nagler, plus incredible edge performance and contrast, with no blackout problems or noticable chromatic aberration. Overall, I have to conclude that the Harry Siebert 36mm Observatory Class EP approximates a score of 9, despite the upper retention ring issue and lack of a respectable container.

Overall Rating: 9
Optics:10 Value:9
Weight: 5 (Veritable Vote)
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Harry Siebert 2" 36mm Observatory Class
Siebert here.

about 5 36mm OB's were made the way described in this review. White delrin ring has now been replaced. Sorry for the ugly white ring.

Harry Siebert

Overall Rating: No Vote
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Harry Siebert 2" 36mm Observatory Class
I recently recieved the 2" 36mm Observatory eyepiece from Siebert Optics. I concur with the other good reviews -- excellent optical quality, HUGE optics, relatively light, and large field of view. This is a VERY nice eyepiece for deep-sky targets, as the views have high contrast, and are bright.
What made this special for me is that I own an Orion 5" (127mm) Maksutov scope that only accepts 1.25" eyepieces. This means that with my 1540 mm focal length, I was doomed to views about as wide as the moon -- even with the best 1.25 eyepieces. Enter Harry Siebert to the rescue: He attached a nice 2" adapter to my diagonal, rebaffled it, and sent the 2" observatory 36mm. This set-up more than DOUBLES any field of view I had experienced before, and this with practically no visible edge distortion!

Overall Rating: 9
Optics:9 Value:10
Weight: 1 (Unreliable Vote)
Date:
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Harry Siebert 2" 36mm Observatory Class
I have been using the Siebert 36mm observatory eyepiece for several months now. It is an outstanding eyepiece both optically and in terms of usability. I have done fairly careful comparsions between the Siebert and the 30 mm Speers WHALER, the B&W 30mm superwide, and the venerable 35 mm Panoptic, all of which are good eyepieces. My scopes are high quality reflectors at f/5.7 and f/6. The Siebert is the nicest and most comfortable of the eyepieces to use. It is significantly better off-axis that either the WHALER or the B&W. I can't tell for sure whether it is better than the 35mm Panoptic or not, neither is perfect, both are very good. The lighter weight of the Siebert makes it easier to use without rebalancing, or a weighted adapter. It is a very very good eyepiece.

Overall Rating: 10
Optics:9 Value:10
Weight: 5 (Veritable Vote)
Date:
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=324154

Harry Siebert 2" 36mm Observatory Class
The Best E.P. I own.

Large FOV, works well in fast scopes. Sharp, contrasty images. I purchased a 2x & 3x barlow just to use this E.P.
at different F.L.

I'm, selling my Pentax XL series to purchase 2" binoviewers because of this experiance with this E.P.

Overall Rating: No Vote
Optics:10 Value:10
Weight: 5 (Veritable Vote)
Date:
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Harry Siebert 2" 36mm Observatory Class
Awesome and flawless eyepiece. NO kidney bean noticed by me in an f/4 and f/4.9 Newt. Sharp, non-distorted images, with excellent color. Generous eye relief good for "visitors" and eyeglass wearers. Price about $200 is fair for this level of quality.

Overall Rating: 10
Optics:10 Value:10
Weight: 5 (Veritable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=359593 

>Awesome and flawless eyepiece. NO kidney bean noticed by me in an f/4 and f/4.9 Newt.  Sharp, non-distorted images, with excellent color.  Generous eye relief good for "visitors" and eyeglass wearers.  Price about $200 is fair for this level of quality.

JULY 2006 UPDATE:  A few months ago I encountered Harry Siebert and his wife at North Carolina's TriStar astronomy gathering.  I mentioned that I had one of his early versions of the wonderful 36mm eyepiece.  He volunteered to upgrade it to his latest specifications FOR FREE.  And that he did.  While he was outside showing attendees the sun through a solar scope, I spoke with his wife, who told me that Harry is obsessed with giving all his customers the finest experience.  What more could you ask of an eyepiece manufacturer?

By the way, I am not an anonymous brick thrower.  Check out my award winning astronomy links web site:  http://astronomy-links.com (keep the hyphen).  Clear skies.
Harry Siebert 2" 36mm Observatory Class
Piece of junk! This thing is assembled from reject optics in a crudely home-made EP body. "Observatory Class" is certainly a rather wild name for this reject from a kid's toybox.

Overall Rating: 1
Optics:1 Value:1
Weight: 6 (Veritable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=374893 

>Piece of junk!  This thing is assembled from reject optics in a crudely home-made EP body.  "Observatory Class" is certainly a rather wild name for this reject from a kid's toybox.

*******************************************

What a coward you are! Put your name on this!

I bet you have never even held one of these fine eyepieces in your hand.

You are a joke.


Don Durbin
>Piece of junk!  This thing is assembled from reject optics in a crudely home-made EP body.  "Observatory Class" is certainly a rather wild name for this reject from a kid's toybox.


I am sorry you had this problem with the eyepiece.  If you would like please contact me and I will either replace or refund you.
Harry Siebert 2" 36mm Observatory Class
I have a pair of these that I use in a Siebert 45mm Elite Binoviewer. This is an excellent eyepiece when used for binoviewing or in Cyclops mode.

The low power views through this in a 2" binoviewer cannot be matched by any other binoviewer on the market.

When used in Cyclops mode this is a great eyepiece with fantastic contrast and it is tack sharp to the edge.

I give it my highest recommendation

Don Durbin

Overall Rating: 10
Optics:10 Value:10
Weight: 5 (Veritable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=423086

Harry Siebert 2" 36mm Observatory Class
Mine is a special 38mm model that Harry made for me, as he said the 40mm Observatory would vignette a bit in my scope. OK, you know all the good stuff from the other reviews: very lightweight, hung together well even if a bit crude esthetically, works well down to around f/6 for my taste, no kidney beaning, no blackouts when scanning, field stop is very sharp, almost no pincushion distortion, good color balance, good contrast, narrow enough to be used in 2" binoviewers, guaranteed satisfaction or your money refunded. However, expect some image softening in the outer 20% to 30% of the FOV. You may notice a reflection from your eyes due to lack of multicoating of the eye lens, which Harry said he fixed on current production.

The FOV is so wide that the EP will vignette in just about any 2" diagonal you stick it in. Your focuser drawtube should be bigger than 2" internally in order to get the most out of the EP if using a fast focal ratio. The 34mm or 36mm version is best for most people, and they will work better on a fast focal ratio Dob.

Overall Rating: 9
Optics:9 Value:10
Weight: 1 (Unreliable Vote)
Date:
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=559352

Harry Siebert 2" 36mm Observatory Class
Bought 2 for my Binocular Newtonian, 12.5 inch f/6. This is the longest focal length wide field eyepiece I can find that will work in a binocular set-up, giving 53x and 1.2 degree TFOV in my Binocular.

Pros: Very light weight but solid construction. Good sharpness nearly to the edge, first rate at the center. Fairly comfortable as a binocular, eye relief adequate to see field stop with both eyes, but those with narrow interpupillary distance (50-55 mm) will have a problem and may have to back off, losing some of the field. Almost NO lateral color or pincushion distortion, making this one of the best lenses for sweeping the Milky Way I have ever used. No kidney bean, but at f/6 the eye must be placed carefully for a fully illuminated field (6mm exit pupil). At f/8 or longer, this is not a problem at all. Views of the moon stunningly sharp with very little light scatter. Excellent throughput, views of the Viel Nebula and North America have the most contrast of any eyepiece in my collection (which includes several Panoptics and Naglers).

Cons: I am nearsighted but have no astigmatism and prefer to observe with no corrective lenses. I can't do that with these eyepieces as objects at the edge become very out of focus. So I wear my contacts. Eye relief not quite enough to use glasses and see the whole field through both eyepieces. A single ghost image on Jupiter or very bright stars, but this is a minor flaw. Comes with press-in "spacers" presumably to help position the eye for full field illumination but these are about 2 mm too long and reduce the field of view to about 55 degrees. Good idea but not quite the right hardware. Like most Siebert products, there is an "almost homemade" quality to the appearance; those wanting fancy eyeguards, knurled surfaces and slick anodizing jobs will not find them here.

Overall: A very good eyepiece, priced about right. If you have a binocular or binoviewer that takes 2" eyepieces (Siebert's is about the only one out there), these fill the low power niche very nicely. Sweeping the star clouds of Scutum or Sagittarius with a pair of these is an unique experience. Barnard's Snake Nebula is very clearly revealed, as are the Ink Spot, dark lanes in the Lagoon, and the subtleties of the North America nebual. Recommended.

Dan Duriscoe

Overall Rating: 9
Optics:8 Value:9
Weight: 5 (Veritable Vote)
Date:
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Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=561170

Harry Siebert 2" 36mm Observatory Class
Harry builds this in a 40mm Observatory model. Like a 41mm Panoptic, it will get the absolute max FOV out of your scope at an increased power over a 55mm TV Plosss, 50mm Ultima or Tak, etc. Be aware of the problems that all such EP's pose before buying one.

Harry admits that the 40mm is not as good in fast Dobs as the 34mm or 36mm Observatory Class. In a normal 2" diagonal, you will also see some vignetting as the FOV is too great and the nosepiece impedes the light cone. Not so bad if you have a long focal ratio scope that has a collimated light cone. It is also softer on edge in a fast Dob than the 34mm and 36mm.

That said, it is about the most comfortable deep sky EP you will ever use. It is half the weight and half the cost, or maybe less, than the top premium brands. There is no way I can justify paying more for them, in cost, weight and size, based on the optical performance I received. In spite of the smaller size and weight, these EP's have a huge eye lens that you can roll your eye around without suffering kidney beaning and blackouts. Contrast is high, sharpness is high, distortion is low, color balance is good, and only the extreme outer edges have softening of the image at f/8 or longer focal ratios. If a Nagler, Pan, or XW has some points on this EP, I'm here to tell you that this EP has just as many points on them. You pick your most important points and make your decision. I own a 34mm Axiom and a 50mm Axiom that I bought previous to this EP. They are very good EP's and share some of the Ob's better features in comparison to the pricier EP's listed above. This EP can cover fairly well for both of them, and at less than half what I paid for both Axioms. If you're not using a fast Dob, and need a 2" EP to stick in your refractor, CAT, classic Cassegrain or Newt that is above f/6 in focal ratio, then I see no need to buy the heavier and costlier EP's. Eyeglass wearers can use this EP with no problem once the smaller inner eyecup is removed from the outer hard plasric eyecup. The inner eyecup does a good job of getting ambient light out of your eye lens. The earlier Observatory EP's did not have a multi-coated top element, and ambient light was a problem for some people. I have dark skies, so I didn't notice it too much.

All the way around, I haven't seen a better EP in this class for what Harry charges in my long focus Mak. Works just as well in an f/10 SCT or a C14. Every C14 owner should check this EP out. When used with a 2" Powermate or Siebert Telecentric, it works very well in f/4 Schmidt-Newts and Dobs as well, and keeps the comfortable eye relief and huge eye lens intact.

I have seen a shorter FL 2" Ob in a 2" Siebert Power Mag Wheel, and for the price of a single Nagler you have three FL's you can switch between instantaneously. Some refocusing was needed in between mag changes, but it was well within the range of a 1.5" travel Dob focuser. I would much rather have that combo than a single Nagler any day, and both together weighed no more than a Nagler.

Overall Rating: 9
Optics:9 Value:10
Weight: 1 (Unreliable Vote)
Date:
By:
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=561797

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