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My Experience with a UC-22 over the past few years.

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#1 gdjsky01

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Posted 25 February 2021 - 02:22 AM

I am trying to keep this to WHAT, not who. Stay on point, not bashing. Here is my experience.

 

Let me tell you all, a long term tale of using a UC-22 loaded with all the goodies.

 

I am a long time (since the 70's) astro-nut.  I have had 60mm, 80mm, 90mm, 20cm and 25cm SCT's, AP APOs, an 18cm APO, 18cm, 28cm, 30cm, and 45cm dobs. I still have 80mm f/15, 90mm Triplet APO, 60mm Ha, 127mm SCT, 120mm ED APO, 15cm Mak Newt, 18cm Dob, 25cm dob, and the 55cm UC-22.

 

So let us get to points. Good points (without too much detail as they speak for themselves)

 

#1 the UC-22's optics by Ostahowski are fantastic. Just everything one could hope for.

#1,5 I really have had little to no collimation issues.

#2 The FT focuser? Great!

#3 I have the astrocrumb filter sider, highly recommended.

#4 And the Markless stalk... really good!

#5 When the scope performs as one would think, 22 inches is wonderful!

 

I'll get to the more not-so-great points even if long...

 

The altitude drive has been a real source of frustration. The drive roller was misaligned when I got it. I have the pics. The assembly was obviously assembled wrong. Not my word, the word of others that have installed such drives. I have never had a large driven large dob so I did not know it was put together wrong, that it would be problematic, and that the ALT drive cable would come off all the time as sent to me. I just did what the instructions said. Put the cable on as per the instructions.

 

You must know, I spent more nights in the first year or so with a JAMMED altitude cable because there is nothing to keep in on the altitude bearing. There is a cut channel in the Teflon™ which goes all the way around the VMB (Virtual Mirror Box) bearings. The channel does nothing however. Even at the bearing touch points as the cable does not ride in the channel it runs on the hard bearing surface. Nor at the two actually touch points of the bearings, and certainly not at the 100 degrees plus elsewhere that the bearings make contact. It does look like the cable would stay in there. But it's not supposed to contact all the way around (I now know.)

 

Most of the teflon is a complete waste as the bearings do not touch it. I understand why. However guess what? That gap between the Alt bearing on the top and the VMB (aka rocker) on the bottom means if you loosen the cable too far, it falls out the side because of the gap between the upper bearing surface and the VMB's bearing surface. Oh I understand the Alt bearing should not ride on the Teflon all the way around for 160 degrees or more. There is the teflon, and there is the channel, and there is 12 inch long gap at the bottom, and there is ALT cable falling out... and the scope if unlucky is jammed with 100 lbs of weight needing to be taken off,

in the dark, to either remove the cable and forget tracking for the night, or get it back on, which can not be done by myself. Indeed I've had three people at once have to lift, guide, and align. It's just too heavy/awkward at that point. There are hoops needed to keep the tension on the cable while the scope is put back on it. Imagine being alone?

 

The whole scope slides side to side when moved by hand or by the drive in altitude. That makes the furniture glides, which are the hi-tech way the UC-22's bearings are kept on the Virtual Mirror Box (VMB) bearings, get pulled out (they are nailed in),  from falling into the ground board on one side and the ground on the other. They work loose because the nails are no match for the 100+ pound force unevenly applied by the lack of alignment, or precision of the VMB and work their way out. I am not against furniture glides, indeed my friends said, "Go get these" and I screwed those in. No nails. However before I did that,  guess what? If the whole 100+ pounds does not fall into the VMB, yes the scope slides sideways enough and the ALT cable falls off. Again. And often chewing up the teflon. Once the whole scope (one side of it of course) fell into the ground board!!! Fifteen thousand dollars?

 

Then there was the teflon square pad on the azimuth bearing which fell out to the side of central bearing it surrounded.

 

If there is no weight on the VMB nothing keeps it in place. So if you CARRY the VMB out of the trunk of the car (which is almost impossible at 90+ pounds, but say you are just lifting it out of a car), that pad, once not centered on the azimuth shaft, will cause the entire VMB to rock as it's not riding true on the ground board (which will also causes a loss of power at random times, as you move the scope in azimuth. Until you are embarrassed by someone who says and this happened, "You know this thing is rocking a bit as I  turn it!" Of course that means you lose your alignment as well.

 

Keep in mind if you are alone, this will means you have take the scope apart, in the dark.  Essentially you are done for the night. If you understand what is going on. Doing so?  As far as the drive? There is no way a normal 60 year old guy, IMO, will be able to fix any of these issue in the dark, by himself. It's just too heavy.  The UC-22 is fine if moving by the wheelbarrow handles. But to lift the mirror out, or the VMB? If daylight that is hard, imagine at night? Not a good idea!

 

Yes years later I am still upset. The best thing about the UC-22 is the views, when the flawed scope moves. Let me say that the ServoCat guy Gary has tried to help. He's really been a great example of support after the sale. Even tho he was not the actual vendor.

 

I have gotten no other support. My friends have Classics and they are great. If you get a good UC-22 or are happy to have to tinker and futz with a $15,000 scope, then maybe the UC-22 is for you. Or you'll get a good one and wonder what am I 'on about'. Fortunately I have friends that have helped. People that have installed their own drives etc on 20's and 25's. Without them the UC22 would have had the drive ripped out years ago. 

 

So bottom line I would not recommend the UC-22. I do not know if the UC15 or UC18 are better. I know the Classics are, as far as I

have seen, fantastic. I'd trade my UC-22 for a tracking 20 classic or a 25 f/4 with no tracking, without even thinking about it. What is above is so. I have others who thank goodness were around to help me, some night. Did I just get an outlier? Maybe so. Am I a malcontent? Sure. Does Toyota make a bad car now and then sure.  But when something is not right, you judge the product by the response you get. Like any product. 

 

I am done. IM me if you want more and I have not again violated T&Cs 


Edited by gdjsky01, 25 February 2021 - 03:00 AM.

 

#2 nicknacknock

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Posted 25 February 2021 - 02:58 AM

Jeff,

 

I only had experience with a friend's 18" F4.5 Classic Obsession, which indeed is a tried and tested design - admittedly quite heavy though and it doesn't come with its own chiropractor as standard! A pity that your UC22" did not perform as expected. Ultra Compact / Light designs generally need more development I think as they have different demons to conquer than your regular truss designs.

 

I had myself a very difficult time with a 12" ultra light design from another vendor - it would not hold collimation under threat of it being trashed by a hammer! I was one step before doing that but then common sense prevailed and I got the manufacturer on the horn and got a refund. I don't know how things are in the USA, but in the European Union, laws are generally in favor of the buyer, even in cross border disputes (I am from Cyprus and Vendor from another European country).

 

At least I take it that after tons of ATMing the scope functions as it should from the onset. You put a lot of effort to keep the scope and make it work, so it seems that you are getting (albeit with a ton of frustration and effort) what you would like out of it.

 

It's good to document what may be design defects or problems arising through use. Some people perhaps facing the same / similar frustrations may either choose to follow your path and power through the problems or just return the scope or perhaps choose a different vendor. It IS a free market after all laugh.gif


 

#3 astrokeith

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Posted 25 February 2021 - 03:04 AM

I have a friend with a 22"UC. He hasn't added the drive for the reasons you describe.

 

Recently I had to completely remake his 'VMB' for him. This was partly down to him not keeping it dry, but it gave me a chance to look at the design, materials and construction.

 

Overall I got the impression it was a smaller design scaled up, but not in proportion to the massive increase in weight it has to bear. The VMB base wasnt thick or strong enough to prevent it distorting under the weight of the scope bearing down on the outside edges. This consequently causes the sides to tilt out and you end up with poor contact of bearing surfaces. The corner brace pieces were way undersized.

 

The original VMB was made from plywood, but IMHO not a good baltic birch ply. Laminations were too thick and the wood was soft. The sides were doweled onto the base, but as the sides are pre-coated in melamine or similar, the mating surfaces aren't glued, just the dowels.

 

Most of the screws were rusted, and some of the fittings too. A scope of that price should have A2 or A4 stainless.

 

I made him a cradle so when in storage the VMB is supported along the two sides under the altitude bearings. 


 

#4 gdjsky01

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Posted 25 February 2021 - 03:11 AM

I have a friend with a 22"UC. He hasn't added the drive for the reasons you describe.

 

Recently I had to completely remake his 'VMB' for him. This was partly down to him not keeping it dry, but it gave me a chance to look at the design, materials and construction.

 

Overall I got the impression it was a smaller design scaled up, but not in proportion to the massive increase in weight it has to bear. The VMB base wasnt thick or strong enough to prevent it distorting under the weight of the scope bearing down on the outside edges. This consequently causes the sides to tilt out and you end up with poor contact of bearing surfaces. The corner brace pieces were way undersized.

 

The original VMB was made from plywood, but IMHO not a good baltic birch ply. Laminations were too thick and the wood was soft. The sides were doweled onto the base, but as the sides are pre-coated in melamine or similar, the mating surfaces aren't glued, just the dowels.

 

Most of the screws were rusted, and some of the fittings too. A scope of that price should have A2 or A4 stainless.

 

I made him a cradle so when in storage the VMB is supported along the two sides under the altitude bearings. 

Thank you Sir. Sure sure you may be validating my point and I thank your expertise. However my friends who have Obsession Classics, are almost to a tee happy. So I did the UC thinking its a premium buy. I am sort of screwing myself by posting these notes. I'd like to trade this scope for another as I said. However I feel also its just important to say be aware. Alas, unless you are a handi ATM/Machinist... why would you? smile.gif Clear skies sir!


Edited by gdjsky01, 25 February 2021 - 03:15 AM.

 

#5 gdjsky01

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Posted 25 February 2021 - 03:22 AM

BTW: To my surprise back then, much of it IS plywood. I would not have thought.


 

#6 starman876

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Posted 25 February 2021 - 07:59 AM

This certainly is changing my mind about a Obsession 18 UC.   The other thing that bothers me is the way I got treated when I called Obsession and asked questions about the 18UC.   I asked when the upgrades were made to stiffen the mirror box.  All I got was I do not remember.  I find that strange that a manufacturere does not remember when certain upgrades were made to improve the scope.  I could not get a straight answer out of this guy on anything.  


 

#7 nicknacknock

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Posted 25 February 2021 - 09:18 AM

Jeff,

 

I do feel your pain, even though my torture lasted for nearly 6 months only. And during that time, whenever I would go out with my observing buddies and that scope, they prudently stayed away from me when I was trying to dial in collimation. In the end, I would give up and just pull out the old but faithful 4" refractor. Considering I used Glatter tools and I would collimate everybody's Newts / Dobs and then smash my teeth on my dob, yeah, I was irked. I then moved to a solid tube design which I passed on, but I still have  love for dobs!

 

I take it that after years of frustration, the Servocat system is not functioning well with that scope due to the scope's inherent flaws. Curious to ask then, since the scope other than the above issue functions well, why not sell it and sell the Servocat system separately to someone who does ATM and get a scope that gives you what you need? I am of the opinion that our hobby is supposed to relax us and help clear our mind, to cope with the stresses of real life, not add to that!!

 

I KNOW the 22" will show much more than the 18", by an order of nearly a magnitude (and not just the faint fuzzies, but really pull out more detail on more prominent DSO too), but since you have a good 18" apparently, why not see what to do with the 22"?


 

#8 aatt

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Posted 25 February 2021 - 03:48 PM

Yikes.I was thinking about getting one eventually. Think I just got talked out it. Sounds like real slipshod design, which is strange considering the game changing thought that went that went into the classic. Obsession seems to be going the way of Discovery with the poor communication and poor build quality control. Disappointing to hear.
 

#9 Jon Isaacs

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Posted 25 February 2021 - 04:33 PM

I KNOW the 22" will show much more than the 18", by an order of nearly a magnitude (and not just the faint fuzzies, but really pull out more detail on more prominent DSO too), but since you have a good 18" apparently, why not see what to do with the 22"?

 

 

Actually a 22 inch goes about 0.44 magnitudes deeper than an 18 inch.

 

Jon


 

#10 msc8

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Posted 25 February 2021 - 10:45 PM

As a former owner of a UC22 there is NO WAY a single person can lift the VMB enough to easily fix the servo cat alt cable when it slips off,  which it does easily.  I rigged up a scissor jack to lift the VMB.  The small jack would lift on the handle that was on the VMB.  Then I could use both hands to fix the cable.  This was no fun.  Originally I tried doing this just by lifting with one hand however even back when I had this as a fit owner the weight on the whole thing with the mirror was too much and could easily pin your hand.  

 

The views were OK with my scope and the mirror test report was exceptional but I can say that with a different scope that does not have as many problems with function I see many more objects per night

 

 

The chair leg glides installed to keep the VMB on track are the ultimate in insult for the price, WTH?  Maybe used for a tinker this would be a great project scope, as I think it can be made better, but not at the new asking price


 

#11 nicknacknock

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Posted 25 February 2021 - 11:04 PM

Actually a 22 inch goes about 0.44 magnitudes deeper than an 18 inch.

 

Jon

I was going by the numbers on Obsession Telescopes website actually, which indicate 0.7 magnitudes.


 

#12 astrokeith

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Posted 26 February 2021 - 03:19 AM

There is a place for ultra compacts, even if they are a compromise. I designed my own, but it took 3 iterations before I am satisfied with its stability and tracking performance.

 

I had to go that route as I drive a Mustang and along with camping gear etc it is the only way I could get it in my car. So I accepted some small compromises but not where they affect observing performance and comfort. One I am left with is set up and take down time. Probably at least an hour or so, but it will run for a week without needing attention.

 

I'm ready to be corrected but think Obsession was the first to seriously introduce UCs. But they havent updated or improved it to overcome what are wide spread problems. I know another scope manufacturer who is keen to find an alternative to ServoCat, another 'old' product. Most of the UC issues can be improved by tweaking and fettering, but the altitude wire issue is a big problem. I've seen people give up on a clear sky because of the wire.

 

The folding altitude bearings is a neat concept for compactness, but it brought the inherent problems. Ensuring no 'bump' when the join is passed plus securing the wire are at the seat of the fundamental problem. For larger models the VMB is under strength to carry the load and distorts.

 

My own design (and that of the Skywatcher UC) reduces the VMB to a base with rollers. This is incredibly stable in comparison. It does require the altitude bearings to be in one piece. A compromise in compactness and speed of assembly, but actually only a 5 minute job in practice.

 

Achieving altitude drive via the rollers is also neat, and in my next iteration I will try that. I havent worked  out how to incorporate a slip clutch yet which for me is essential.

 

In the end, if you really want a 22", the Obsession could be made to work, but I would budget for a VMB rebuild. The excellent optical performance warrants it.


 

#13 a__l

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Posted 26 February 2021 - 06:13 AM

If the design allows, it is necessary to install 4 side stops that prevent side sliding. This must be made removable. Steel and Teflon.


 

#14 a__l

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Posted 26 February 2021 - 06:46 AM

I found Obsession photo. It is necessary to replace the round washers (red arrows) with side stops (second photo). Surface milled to the required depth (red arrow). Reinstall to a different position the anti-slip screws (on altitude bearings). It may be necessary to sand the joint between the two bearing halves.

Attached Thumbnails

  • obsession__ (1).jpg
  • Stop (1).jpg

Edited by a__l, 26 February 2021 - 07:16 AM.

 

#15 Jon Isaacs

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Posted 26 February 2021 - 07:03 AM

I was going by the numbers on Obsession Telescopes website actually, which indicate 0.7 magnitudes.

 

The math is pretty clear:

 

LM2/LM1 = 2.51 x log((22/18)2) = 0.44 magnitudes.

 

Jon


 

#16 nicknacknock

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Posted 26 February 2021 - 07:09 AM

The math is pretty clear:

 

LM2/LM1 = 2.51 x log((22/18)2) = 0.44 magnitudes.

 

Jon

Chalk another thing that Obsession Telescopes need to fix. Maybe send them thislol.gif


 

#17 sanbai

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Posted 26 February 2021 - 10:56 AM

The math is pretty clear:

LM2/LM1 = 2.51 x log((22/18)2) = 0.44 magnitudes.

Jon

sorry to go off topic.

Jon, you challenged my rusted neurons (thanks!). I had to excercise a bit my math knowledge and solving the formula was a proper way.

The 2.51 should be actually an exact 2.5.
To simplify:

LM2/LM1 = 2.5 * log[(D/d)^2] = 5* log(D/d)

I guess the 2.51 comes from initial rounding of the factor of magnitude increments. This rounding is not necessary and the actual definition works better! The definition for a factor of 1.0 magnitude increment according to wikipedia is 100^(1/5) (which is ~2.51). Using the accurate 100^(1/5) (= 10^0.4), the formula is actually easier to solve, and you come up with an exact number.

Apologies for the interruption.

Edited by sanbai, 26 February 2021 - 12:20 PM.

 

#18 a__l

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Posted 26 February 2021 - 06:03 PM

Anti-slip screw blue arrow. I do not see others (at least in this photo). 

The second photo is how this is installed on my telescope.

I think that by this simple method your Alt cable problems will be solved.

 

Ps. The classic Obsession Alt bearings are made in the form of a cone, so there is no problem there (or mild).

Attached Thumbnails

  • obsession__ (1).jpg
  • Alt_3_Iz.jpg

Edited by a__l, 26 February 2021 - 06:38 PM.

 

#19 a__l

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Posted 26 February 2021 - 06:50 PM

And further. The round washers on UC are weak. I saw the owner of such a telescope fixing a piece of ordinary plywood instead of them on ordinary nails. Because the original ones fell off (or broke)
You need to fasten 8 screws firmly. For example, I screwed these inserts into the rocker (photo). You can buy standard screw inserts. Add epoxy for extra strength.

Attached Thumbnails

  • Ввертыши_Iz.jpg

Edited by a__l, 26 February 2021 - 07:06 PM.

 

#20 a__l

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Posted 27 February 2021 - 04:45 AM

It's easy to modify. The main part of the price of 15 thousand is Optics + ServoCat +FT focuser. This is a piece product (not mass) made by hand, therefore this is the price.

I spoke with D. Kriege, he has no way to replace steel parts with stainless steel. In particular, it is a mechanism for joining bearings. The price is increase.


Edited by a__l, 27 February 2021 - 05:18 AM.

 

#21 cuzimthedad

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Posted 27 February 2021 - 01:18 PM

This thread is now locked but will remain in the forum for reference purposes.


 


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