Siebert 38mm Observatory, Custom Order

Started by DuckView, 07/04/2006 05:43AM
Posted 07/04/2006 05:43AM | Edited 07/04/2006 06:03AM Opening Post
I called up Harry to talk about his Observatory EP's, specifically the 40mm FL. He let me know right off that there would probably be image cutoff issues in my LOMO 150 Mak-Cass using the Stellarvue dielectric diagonal. He offered to custom make me a 38mm version instead of stepping all the way down to the 36mm FL. No extra charge for the special FL, so I ordered and waited. Several weeks later it arrived. It had the standard Siebert machined turned finish on the outer body. Interior had very rough black paint similar to what LOMO scopes use that Harry says "sucks light". There are six set screws visible on the exterior that obviously lock things in place. I now have 9 Siebert EP's, and not a single one has ever developed a rattle, like Japanese and Chinese EP's often do. They all come in a bolt case for protection.

I noticed some image cutoff in my LOMO 150 and Stellarvue NH II, both with my 2" Stellarvue dielectric diagonal. Pulling out the diagonal and looking through the EP revealed that the nosepiece was indeed cutting off the image edges a bit. A 34mm Axiom has no problem, and neither does a 50mm Axiom. The 38mm Observatory must therefore be quite wide in true FOV. With no scope available that can use the whole FOV, I can't do a star drift to determine the true FOV. I'll have to take Harry's word, whatever that was, until I can do a test. It's a wide FOV, but not a Nagler by any means. Definitely in the Axiom or Panoptic class.

If you use the Stellarvue 2" dielectric diagonal or equivalent, get the 36mm Observatory as it's all you can use. Also, the EP is quite light for such a wideangle 2" EP. It doesn't overpower the NH II on the Grab-n-Go mount as a Nagler would. Harry states 9 oz., but I did not weigh it. It is all aluminum, except for glass and rubber/plastic eyecups. The eyecups are a bit strange, as it is a nested design. Eyeglass wearers will pull out the central nested rubber eyecup to get a full FOV. I leave in the rubber eyecup to cut down on glare when I observe in town. The large primary eyecup is hard plastic, except for the central part that would touch your glasses, which is rubber. The nested eyecup is a friction fit of rubber against rubber. Looking down from the top, the EP is all black, what isn't glass. There's a lot of glass there to look at. The bright natural aluminum body makes it easy to locate at night, I have found out. Coating reflections are the normal Siebert yellow and blue colors. Color balance of images seem fairly neutral. At least no major color shifts have been noticed compared to my Ultimas and Axioms.

This is, obviously, a deep sky type of EP. Viewing very bright objects like Jupiter reveal more glare and reflections than an Ultima or even an Axiom, for instance. Harry's own Star Splitter planetary series deliver a blacker background and less light scatter. A lot of the problem will be stray light shining on the EP or reflected from your face, so an observing hood of some type has been necessary for me when observing in town at night. I leave the nested eyecup in place when observing in town to help shield the eye lens from glare. Fine detail is quite good, similar to what you would get from an Axiom in my scopes. Edge sharpness could be better in fast scopes. Rectilinear distortion is quite low, similar to an Ultima, so terrestrial observing is quite good. I get no image cutoff with my 34mm Axiom in my diagonal and scopes; therefore, I genberally use it more often in astronomical observing. Size is very similar between the two. Eye lens is slightly bigger in the 38mm Observatory. Field stop is slightly bigger in the 38mm Observatory, but the objective lens is a bit smaller. 34mm Axiom is slightly heavier, as it is brass barrelled. 34mm Axiom cost me less, as I got it on a closeout, but normally runs $40 higher at regular street prices. The multi-colored coatings of the Axiom tend to work a bit better, I would say.

The comfort factor is about equal for both EP's. Kidney beaning and blackouts have not been an issue in the 38mm Observatory. If you need a lightweight 2" EP to max out the FOV and light gathering ability of your scope, can't afford a Panoptic 35mm or 41mm or don't want their size and weight, then the Siebert Observatory Series is a viable alternative. Used 34mm and 40mm Axioms sometimes come up for sale and are great bargains when they do, but since being discontinued they are getting harder to find brand new. Observatory Series are not available under about 30mm in FL, so basically you pick the one that maxes out the FOV and/or exit pupil size in your scope. They will cause less of a balance issue than long FL Pans or Naglers in Dobs and smaller refractors. There is basically a nonexistent used market as far as Siebert Observatory EP's go right now, so you had better plan on spending the $199 for a new one if you want one, but Harry gives a money back guarantee and at least a 60-day trial period. The trial period is rather generous as it is unlikely you will want to return it after getting used to it. It's not a Pan or Nagler, but it has it's own charms, besides the much lower price.

Don't put much faith in my personal observations if you're wanting to try one. Since there's a money back guarantee, I would buy and try for most of the trial period and see if I liked it if I needed a 2" EP of the wideangle variety. Like a Rickenbacker guitar, it's a bit of a strange duck, with a finish nobody else uses, but Siebert Optics has it's legion of dedicated followers. It also has its critics on the other astronomy website that seems to have an anti-Siebert bias. Most of the Excelsis reviews are positive, except for one guy that had an axe to grind, it seems. If a Siebert EP of mine ever falls apart, I'll let you know, but so far no rattles and no major complaints. If you want the last bit of performance, ante up and get a Tele Vue or whatever at 2 or 3 times the price. If you like to kick back under the stars and see a lot of things without breaking the bank, then this is a good place to start your funky Siebert EP collection. You too can join the ranks of "Siebert Barbarians" with naked EP's and more party money for barbecue and beer this summer than your Pan and Nagler toting astrogeek acquaintances. wink

Phil

P.S.

The Observatory Series has a strong paint smell, obviously from the interior coating, when you first get it. After several days of use, it largely goes away. These do not sit on dealer shelves for months or even years as some EP's do and thus have no chance to air out in the box and the plastic bolt case prevents much off gassing anyway. As soon as it's built, it's on the way to you and will have that "new aroma" much like new cars do. Just another idiosyncracy you get used to with Siebert EP's.