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Obsession 15 UC

hrgreen

By hrgreen
in Member Equipment Reviews

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hrgreen

hrgreen

Posted
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Though I have had this scope for some weeks, there hasn't been a break in cloud cover until last mid-week here in east central Florida.  Finally got first light.   Dobs are new to me, so much to learn.

The scope is mechanically an ideal compromise for me, as the Virtual Mirror Box is within my safe limit to lift (45 pounds) in and out of my small car.  The ALT upper bearing is hinged, and can  be folded, then the ring can sit on top, making a package that can fit into just about any trunk or boot.   Also, being an f4.2, it doesn't require me to use a stepstool.   Its truss design is made with quick but sturdy connectors using captive fingerbolts, and the trusses and ring are light.   In other words, a good one-man scope.   At home, I store it in a front bedroom with wheelbarrow handles installed, and having installed a few short ramps, I can wheel it fully assembled into my front yard.   There are braces to further stiffen the ALT bearing if you see a need; I haven't yet.  The standard 2" focuser is a dual-speed FeatherTouch.  NO tools are needed for assembly.  Everything fits the way it should.

I ordered mine with 10K DSC's and the Argo Navis, which I'm still learning to use.   I also installed a Stalk and StellarCAT's Powered Ground Board kit, to allow powering the Argo, secondary dew heater and fan from 12 volts, with complete cable management.

StellarCAT originally designed the ServoCAT GOTO drive for Obsessions, and I'll be installing the Junior version in a week or two.   Many don't feel the need for this, but I find that using high power without a drive keeps me unpleasantly busy.   I picked the Junior because it is quieter, and my neighbors might thank me.

The lightweight structure seems pretty rigid even without the braces, but not having owned any traditional Dobs, I can't compare them.  The bearings seem quite smooth.

The mirror is a Galaxy standard-thickness, but I ordered a premium figured one, with an interferometer-measured Strehl value of 0.971.  Hudek supplies a comprehensive printout on request.  There probably are few times local seeing will allow appreciating this, but I don't plan on ever replacing this scope, so I went for it. 

So far, I have had just time to look at the planets and a few globulars and double stars, using 8, 13 and 21 mm Ethos and a 4.7mm ES.  The two nights were relatively dry and steady for Florida, and Saturn showed more ring and surface detail than I have ever seen, including on our local college 24" (which needs cleaning).   Jupiter also, but I didn't have a needed neutral filter.   M5, M13 and M92 showed more stars than I have ever seen.   Star images both sides of focus looked good,  The images held up well even at 340X.

I come to this scope from a Celestron 9.25 HD on a CEM60EC mount, a very nice combo.  It would certainly be better for AP, but I opted for visual, and this unit blows it away so completely for faint stuff that I am very pleased I made the jump.

Hal Greenlee

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RT65CB-SWL

RT65CB-SWL

Posted
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Hi Hal and welcome to SGL. :hello2:

I orderd a copy of the DVD lastyear, (2014). For the time being I think it is going to be the nearest I am going to owning one. They certainly look impressive. :icon_salut:

Clear skies.

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John

John

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Great report Hal - thanks for posting it :smiley:

An Obsession scope under dark Florida skies must be a wonderful experience. You have an excellent taste in eyepieces as well I see :wink::smiley:

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hrgreen

hrgreen

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One thing I didn't mention that makes setting up the scope easy is using Howie Glatter's 2" collimator and Tublug.  These allow aligning the primary while providing a Barlowed target image easily seen from that end, without removing the shroud.  They are very well made and make short, foolproof work of the job.  I also have a crosshatch accessory that shows exactly the centering of the secondary.  I highly recommend these.

Hal

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BeanerSA

BeanerSA

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Great writup Hal

Sounds like a great premium scope.

Does anyone know how much / how safe would be shipping to the UK for one of these beuties?

Paul

They ship all over the world. Email them for a shipping quote.
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hrgreen

hrgreen

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Thanks again for your replies. I don't have a good picture of the scope, maybe later, but there are some on the Obsession website.

Faulksy, I have a Paracorr II, but have not tried it yet. Things have been looking pretty good without it, although I haven't looked closely for coma yet.

Besides Televue EP's, I have ES 4.7, 8.8 and 14 mm 82 degree. These seem quite good. I want to compare the 8.8 to my 9 mm Nagler when I get a chance. The ES were bargains at the introductory prices, about $80, and I plan to keep them for public star parties.

Hal

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  • 1 month later...
hrgreen

hrgreen

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My installation of the ServoCat Jr. drive system went well. StellarCat doesn't have a template or good photo for mounting the ALT motor on a 15 UC, but I was able to figure it out. I also realized that there is a disadvantage to the ServoCat. Normally, a person working alone would want the (Virtual) Mirror Box and Rocker Box to be separated for transportation, because together the weight is kinda high. But putting them back together is complicated by having to thread a cable the length of the lower ALT bearing while assembling, seemingly impossible for one person. I found someone has figured out a way to do it with rubber bands, so have to try it.

I noticed that the scope could rock slightly in elevation when at low angles. It seemed logical that this had to do with the front upper bearing fold-out pieces not being aligned. I made a radius template, which showed one was off. Found that the hinge bolts were not fully tightened on that side. Took minutes to fix.

Really like this scope and what I can see with it.

Hal

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  • 1 year later...
hrgreen

hrgreen

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A few additional notes

I found it easiest to keep the VMB and Rocker Box together when moving the scope in and out of the car, although the rubber band method will allow me to re-assemble them alone.  A little more weight to handle, but OK.  I changed cars to the even smaller Prius C, which has almost no room behind the back seat, and found I could load everything after the seat folded down.

I obtained a Nexus DSC/WiFi to use in place of the Argo Navis.  I do like it better; got tired of spinning that AN dial and filling out names.  It links to SkySafari 5 in my I-pad.  The display is easier to read, and I have more choice of alignment stars.

The scope has not shown any evils since I readjusted the bearing, but I believe with heavy local light pollution, it could gain from a larger light shield opposite the eyepiece.

Hal

 

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Hobbes

Hobbes

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Hi Hal

I have recently become an Obsession owner. In my case a second hand 18" classic. Wonderful scope and I'm very much enjoying it. I keep meaning to write up a review but Christmas preparations keep getting in the way!

My one frustration is trying to get the JMI NGC-Max digital setting circles fitted by the previous owner to talk to SkySafari 5 on my iPad using a SkyFi connection. I've been corresponding with Bill Tschumy at Simulation Curriculum but so far to no avail.

I have been considering ordering an Argo Navis/Stellarcat combination from Obsession and retro fitting it and was interested in your comment about preferring a Nexus DSC/WiFi to use in place of the Argo Navis.

Did you try linking the Argio Navis to the iPad/Skysafari? If so were there any issues with it?

Regards

Rob

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LukeSkywatcher

LukeSkywatcher

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I just watched the free dvd that Obsession sent me a couple of weeks ago. I was AMAZED at just how quick and easy the scopes are to set up. I really liked the compact 18" scope at the end of the dvd. Sadly they didnt stick a camera down the focuser of any of the scopes to show the views. I'm sure they are sublime though.

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hrgreen

hrgreen

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It IS quick and easy to set up my basic scope.   The construction is light enough that at 78, I am able to lift the Rocker Box and VMB with (full thickness) mirror into and out of my car, and mounting the struts/front ring takes only a few minutes.  There is no doubt about where anything goes, and no adjustments to make except minor collimation.  Installing all the accessories does take some time.

A club member has a standard 18" Obsession and sets it up alone, but he carries the mirror separately.   I'm not willing to handle the mirror, and I prefer to uncover it only after everything else possible is done, and cover it before any teardown.   The UC's are made to nest into a light, compact package; standards would be too large for my car and too heavy for me.  My operative question was "what scope would give me the most aperture, but be within my physical limits?" 

Hal

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