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Obsession 18" UC

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#1 starman876

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Posted 23 February 2021 - 08:46 AM

How many have had the pleasure to use the Obsession 18" UC.   I may be buying one of these and want some feedback what people think of them. This one comes with the Servo Cat goto drive system.

 

here is the link for Obsession

 

https://www.obsessio.../18UC/index.php


Edited by starman876, 23 February 2021 - 08:59 AM.


#2 MrRoberts

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Posted 23 February 2021 - 09:44 AM

Had the pleasure to buy Dave's 15" classic about 4 years back.  I sadly had to sell it. These are stunning performers. The 18 would probably offer brighter views of course.

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#3 Don W

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Posted 24 February 2021 - 12:39 PM

Dave brought the prototype to a semi-private star party we do a couple times a year in Upper Michigan in 2007. There were a number of Obsession owners there and we put it through its paces. We were all pretty impressed with it. I had a Obsession 18" Classic at the time.

 

That fall I helped Dave deliver a production 18" UC to Australia and we used it for a week before turning it over to the new owner. I had it to myself for several hours over that week and it performed very well.

 

Just my opinion but I would not hesitate to get an 18" UC.


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#4 starman876

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Posted 24 February 2021 - 01:24 PM

Dave brought the prototype to a semi-private star party we do a couple times a year in Upper Michigan in 2007. There were a number of Obsession owners there and we put it through its paces. We were all pretty impressed with it. I had a Obsession 18" Classic at the time.

 

That fall I helped Dave deliver a production 18" UC to Australia and we used it for a week before turning it over to the new owner. I had it to myself for several hours over that week and it performed very well.

 

Just my opinion but I would not hesitate to get an 18" UC.

Looks like I will be pulling the trigger on this one.  I was really hoping for a 20", but 18" should be easier to manage in and out of the house.    Thanks for the inout. really appreciate it. 


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#5 Jon Isaacs

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Posted 24 February 2021 - 03:25 PM

I've texted my friend Jeff who has an 18 inch UC with a StellarCat, at least it had a StellarCat. 

 

He's an actual owner.  Hopefully he'll share his experiences. 

 

Jon



#6 JeffMartin

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Posted 24 February 2021 - 03:51 PM

Hi,

 

I have an UC18 with servocat.  If I were buying now, I'd buy a classic. 

 

As we know, dob designs are based on tradeoffs.  If you need to put your dob in a travel case or if you need to carry your giant dob up and down stairs (say, from your upstairs observing deck to the car for dark site observing), then the UC Obsession series is great.  I could carry the bottom (ground board, virtual mirror box, AND 18 mirror) pretty easily.  Can't imagine that with any other design.

 

Now, I don't have stairs to navigate and the UC's compromises don't suit me.  These include:

 - the wheelbarrow handles attach to the mirror box: with the handles attached you can view from 80-degree altitude upwards.  That means you have to take the handles off to observe. That one-minute per bolt annoys me (silly, but it does (I put some quick release (5-seconds per) on my classic sytles)).

- the alt-bearings fold (so they fit in the ATA case).  There are braces that are recommended to stiffen the bearings.  They need to be unscrewed to allow the shroud bottom to be lifted.

- the alt-encoder arm is interfered with by the wheelbarrow handles.  The arm has to come off if you're adding or removing the handles.

- the hot water tub base that serves as a mirror cover doesn't quite fit in between the stabilizer arms.  getting that in and out in the dark is like insert a woman's diaphragm for her (but not as fun).  I scratched the mirror with it once.

 

I built a dolly, so that I never have to attach the handles.  It's ugly, but it makes it as easy as rolling out a classic.  So, dolly it up and rig a better mirror cover and you're good.

 

Adding the ServoCAT nearly ruined it for me.  But two primary reasons: 1) I was using a Nexus and SkySafari.  Prior to the Nexus DSC, you had to use DeepSky Browser to get an alignment.  Just way too many separate systems between the mirror and the navigation.  Had two have several cheat sheets to remember (which I didn't). 2) My azimuth decoder failed at some point.

 

Adding a Nexus DSC as my DSC made all the difference in useability.  I find the interface much easier and intuitive then the SkyCommanders.  Argo Navis, I just couldn't get past having to learn that system.  Obsession<-->ServoCAT<-->Nexus DSC works pretty well and pretty happily.  It's easy enough that I seldom turn the iPad on for SkySafari, but it pops right in.

 

Note - and your mileage may vary and it's been a long time since I had it tracking a HIGH power -- the tracking appeared to be incremental: short jumps in tracking rather than a continuous track (it's as if there was too much friction along the alt bearing; as if it would stick until the cable built up enough tension to break the static friction and it would jump ahead and then rest again.).

 

Also: the ServoCAT cable running along the alt-bearing is a giant pain in the a$$.  If you let it get too slack, it will derail and it's a mess to get back on.  That's probably the biggest "redesign opportunity" for the whole package.  

 

All this has been off the top of my head, so I might have some details wrong (in particular the base interferences (since there are so many)).

 

If I were to resell this, I would put in the advertisement (I think I have already): "I do not recommend this scope for a novice.").

 

But, I love the mirror (Terry Ostahowski) and I have a memory of tracking Mars at 500x at an opposition that will stay with me forever.  That's kind of priceless.

 

-jeff


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#7 starman876

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Posted 24 February 2021 - 05:42 PM

Hi,

 

I have an UC18 with servocat.  If I were buying now, I'd buy a classic. 

 

As we know, dob designs are based on tradeoffs.  If you need to put your dob in a travel case or if you need to carry your giant dob up and down stairs (say, from your upstairs observing deck to the car for dark site observing), then the UC Obsession series is great.  I could carry the bottom (ground board, virtual mirror box, AND 18 mirror) pretty easily.  Can't imagine that with any other design.

 

Now, I don't have stairs to navigate and the UC's compromises don't suit me.  These include:

 - the wheelbarrow handles attach to the mirror box: with the handles attached you can view from 80-degree altitude upwards.  That means you have to take the handles off to observe. That one-minute per bolt annoys me (silly, but it does (I put some quick release (5-seconds per) on my classic sytles)).

- the alt-bearings fold (so they fit in the ATA case).  There are braces that are recommended to stiffen the bearings.  They need to be unscrewed to allow the shroud bottom to be lifted.

- the alt-encoder arm is interfered with by the wheelbarrow handles.  The arm has to come off if you're adding or removing the handles.

- the hot water tub base that serves as a mirror cover doesn't quite fit in between the stabilizer arms.  getting that in and out in the dark is like insert a woman's diaphragm for her (but not as fun).  I scratched the mirror with it once.

 

I built a dolly, so that I never have to attach the handles.  It's ugly, but it makes it as easy as rolling out a classic.  So, dolly it up and rig a better mirror cover and you're good.

 

Adding the ServoCAT nearly ruined it for me.  But two primary reasons: 1) I was using a Nexus and SkySafari.  Prior to the Nexus DSC, you had to use DeepSky Browser to get an alignment.  Just way too many separate systems between the mirror and the navigation.  Had two have several cheat sheets to remember (which I didn't). 2) My azimuth decoder failed at some point.

 

Adding a Nexus DSC as my DSC made all the difference in useability.  I find the interface much easier and intuitive then the SkyCommanders.  Argo Navis, I just couldn't get past having to learn that system.  Obsession<-->ServoCAT<-->Nexus DSC works pretty well and pretty happily.  It's easy enough that I seldom turn the iPad on for SkySafari, but it pops right in.

 

Note - and your mileage may vary and it's been a long time since I had it tracking a HIGH power -- the tracking appeared to be incremental: short jumps in tracking rather than a continuous track (it's as if there was too much friction along the alt bearing; as if it would stick until the cable built up enough tension to break the static friction and it would jump ahead and then rest again.).

 

Also: the ServoCAT cable running along the alt-bearing is a giant pain in the a$$.  If you let it get too slack, it will derail and it's a mess to get back on.  That's probably the biggest "redesign opportunity" for the whole package.  

 

All this has been off the top of my head, so I might have some details wrong (in particular the base interferences (since there are so many)).

 

If I were to resell this, I would put in the advertisement (I think I have already): "I do not recommend this scope for a novice.").

 

But, I love the mirror (Terry Ostahowski) and I have a memory of tracking Mars at 500x at an opposition that will stay with me forever.  That's kind of priceless.

 

-jeff

What year is your UC.  I was reading that somewhere around 2012 braces were added to keep the scope in alighnment when moving it around to different objects.  Any issues with that?   



#8 msc8

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Posted 24 February 2021 - 10:23 PM

Hi 

 

I owned a 2013 UC22 which I sold as I was unhappy with its compromises.  Jeff listed some of them and they are present in I think all the UCs.  Do a search on UC18 and read all the reviews.  When I bought mine a couple of folks were unhappy but many reviews were OK.  I should have payed more attention to the problems listed as they were what i found myself

 

For me:

 

Single ring wooden UTA along with long truss poles flexed too much and collimation would not hold for altitude movement at least not to my expectation. You could put a laser in the focuser and watch the dot move as you move the scope

Always fighting with servo cat cable, constantly falling off and with the full thickness mirror on the UC22 lifting the mirror box for one person was impossible without getting your hand crushed if you couldn't lift all the weight

Heavy UC is not ultra light

Full thickness slow cooling needlessly heavy kinda defeats the portable UC design

 

The mirror box is guided on the rocker by 4 cheap chair glides which pop off all the time,  Really on a 8-12k scope?

 

I replaced the UC22 with a NMT 20


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#9 starman876

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Posted 24 February 2021 - 11:32 PM

The more I learn about the UC 18 the more I realize that to make this scope aceptable will require some re engineering.  If these scopes are so problematic why do I not see more reviews of them?



#10 JeffMartin

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Posted 25 February 2021 - 09:42 AM

It's not as smooth and stable as a Classic, and a ServoCAT adds a LOT of complication to the overall experience.  But they serve a niche very well:  you can carry it up stairs in two trips and take it on a plane.  A re-engineering of the base would yield some improvements, but it would only become bigger and heavier.  Tradeoffs...  I should fly it somewhere, just to fall in love all over again.  :)



#11 bbasiaga

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Posted 25 February 2021 - 10:06 AM

I have observed through one several times at an annual star party I attend.  They seem to work well, are easy to use and the views are very good.  I wouldn't know anything about the setup/teardown as the owner does all of that.  He is happy with it as he can move it on his own and set it up, and doesn't require a trailer. 

 

-Brian



#12 dustyc

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Posted 25 February 2021 - 11:36 AM

I can see getting ALT/AZ tracking on the traditional dobs, more room for the mechanicals. But the UC's are bare bones, minimal designs meant for easy travel in a car or small SUV. Mine sample doesn't have any tracking but moves smoothly and keeping a target centered hasn't been an issue . DSC's are great option and add minimal complication to the setup and teardown.  



#13 starman876

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Posted 25 February 2021 - 12:25 PM

I can see getting ALT/AZ tracking on the traditional dobs, more room for the mechanicals. But the UC's are bare bones, minimal designs meant for easy travel in a car or small SUV. Mine sample doesn't have any tracking but moves smoothly and keeping a target centered hasn't been an issue . DSC's are great option and add minimal complication to the setup and teardown.  

that is what I think.  Tracking might be nice, but in a dob strucure like the UC it might require some serious modifications to work properly without anyone complaining.  of course engineering is always a comprimise and cost is #1 too ensure profit.  I see a lot of  these advertised with comments on how few times the scope has been used.  in my opinion a scope that provides wonderful views is going to be used all the time.   



#14 dustyc

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Posted 25 February 2021 - 01:33 PM

Scope use could be dependent on a lot of things, wonderful views being one of them. I could look at how many times mine has been taken out to a dark site and been disassembled and reassembled (5) and count that has to how many times it's been used and take that number for resale purposes. I could also use the number it's been out in my back yard (60 or more) where I just wheel it out with the handles and go. 

Weather is another factor too. Somebody decides to "go big" with their 1st scope and gets frustrated when the weather and their schedule doesn't work out and sell it after just a few sessions.



#15 starman876

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Posted 25 February 2021 - 02:23 PM

Scope use could be dependent on a lot of things, wonderful views being one of them. I could look at how many times mine has been taken out to a dark site and been disassembled and reassembled (5) and count that has to how many times it's been used and take that number for resale purposes. I could also use the number it's been out in my back yard (60 or more) where I just wheel it out with the handles and go. 

Weather is another factor too. Somebody decides to "go big" with their 1st scope and gets frustrated when the weather and their schedule doesn't work out and sell it after just a few sessions.

My portaball used to get used a lot until it got banned from the main level.   My wifes friends eyed it like we were hiding a body in it.   I have no love for carrying that 12.5" scope up and down stairs.   Guess its time to sell it.   However, the UC series looked like they had so much promise untill I started hearing all the downsides.  Maybe one without the servo cat would be the way to go.


Edited by starman876, 25 February 2021 - 02:25 PM.


#16 dustyc

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Posted 25 February 2021 - 02:41 PM

If I wanted tracking in the future I would get ones of those equatorial platforms and place the scope on that. I think you can track for 20 minutes or so. 



#17 Jon Isaacs

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Posted 25 February 2021 - 04:58 PM

If I wanted tracking in the future I would get ones of those equatorial platforms and place the scope on that. I think you can track for 20 minutes or so. 

 

They track for an hour or more but they also add about 6 inches in height. With a tall scope like the UC, thats an important 6 inches.

 

There are other scopes to consider..

 

Jon



#18 starman876

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Posted 25 February 2021 - 06:19 PM

They track for an hour or more but they also add about 6 inches in height. With a tall scope like the UC, thats an important 6 inches.

 

There are other scopes to consider..

 

Jon

The traditional dobs I am not interested in.  I am looking for something like the UC.   Guess the hunt goes on.



#19 CHASLX200

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Posted 25 February 2021 - 07:25 PM

They track for an hour or more but they also add about 6 inches in height. With a tall scope like the UC, thats an important 6 inches.

 

There are other scopes to consider..

 

Jon

Don't think it would work with my setup as i don't see a way to roll out the whole scope with a EP.  I also hear they can cause trouble for sling mounted mirrors.



#20 CHASLX200

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Posted 25 February 2021 - 07:26 PM

The traditional dobs I am not interested in.  I am looking for something like the UC.   Guess the hunt goes on.

What do you plan to view?  Got the seeing that allows high powers in a big scope?
 



#21 starman876

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Posted 25 February 2021 - 07:58 PM

What do you plan to view?  Got the seeing that allows high powers in a big scope?
 

my 12.5" portaball gives awesome views.  There are moments where the seeing makes it worth the wait.   The portaball now lives in the lower level of the house and I have to carry it up stairs to get it out.   I have noticed that each year I live things seem to keep getting heavier.   I need to work out more.  The portaball a couple of years ago was easy to carry. 



#22 GeneT

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Posted 25 February 2021 - 08:05 PM

"I have an UC18 with servocat.  If I were buying now, I'd buy a classic."

 

I agree with this assessment. I have owned both a 20 inch Obsession Classic and an 18 inch UC. The 20 inch was too much weight and hassle for me to load, unload, set up and set up. However, it was an excellent telescope in all respects. However, due to its size, was too much for me. I sold the 20 incher and bought a 12.5 inch Portaball. I is a fun, and perfect telescope for me. When the Obsession Ultra Compacts came out, I thought that the footprint of the 18 UC would be close to the 12.5 inch Portaball. So, I bought an 18 UC--loaded. Compared to the Obsession Classic, I was disappointed. In my opinion, overall it just was not nearly as well built. The upper assembly was made of a type of wood (I forgot the exact type and name.) However, it would not hold collimation. A friend attached an aluminum ring around the wood, and that fixed the problem--for about $200.00. Go to Obsession's web site and look at the secondary. Notice that it sits up several inches above the ring/upper assembly. It has a tongue on the opposite side of the secondary. That is not enough. However, the Obsession Classic has an upper assembly that serves as a 360 degree baffle, i.e. the secondary is surrounded by a baffle. Because of the UC's baffle, I had stray light problems that were a big nuisance. There were several other aspects of the UC that I did not like. If someone wants an ultra light telescope, I would look at some other options. Ending this on a positive note, I am happy to endorse the Obsession Classic, and I believe it is excellent value for the money. 


Edited by GeneT, 26 February 2021 - 12:50 AM.


#23 CHASLX200

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Posted 25 February 2021 - 08:07 PM

my 12.5" portaball gives awesome views.  There are moments where the seeing makes it worth the wait.   The portaball now lives in the lower level of the house and I have to carry it up stairs to get it out.   I have noticed that each year I live things seem to keep getting heavier.   I need to work out more.  The portaball a couple of years ago was easy to carry. 

I guess that has a Zambuto mirror?  Well a 18"' mirror as good as a Zambuto will be a killer for planets.



#24 starman876

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Posted 25 February 2021 - 10:02 PM

I guess that has a Zambuto mirror?  Well a 18"' mirror as good as a Zambuto will be a killer for planets.

Yes the Zambuto mirror.  Any scope with the Zambuto mirror gives awsome views grin.gif



#25 starman876

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Posted 25 February 2021 - 10:06 PM

"I have an UC18 with servocat.  If I were buying now, I'd buy a classic."

 

I agree with this assessment. I have owned both a 20 inch Obsession Classic and an 18 inch UC. The 20 inch was too much weight and hassle for me to load, unload, set up and set up. However, it was an excellent telescope in all respects. However, due to its size, was too much for me. I sold the 20 incher and bought a 12.5 inch Portaball. I is a fun, and perfect telescope for me. When the Obsession Ultra Compacts came out, I thought that the footprint of the 18 UC would be close to the 12.5 inch Portaball. So, I bought an 18 UC--loaded. Compared to the Obsession Classic, I was disappointed. In my opinion, overall it just was not nearly as well built. The upper assembly was made of a type of wood (I forgot the exact type and name.) However, it would not hold collimation. A friend attached an aluminum ring around the wood, and that fixed the problem--for about $200.00. Go to Obsession's web site and look at the secondary. Notice that it sits up several inches above the ring. It has a tongue on the opposite side of the secondary. However, the Obsession Classic has an upper assembly that serves as a 360 baffle. Because of the UC's baffle, I had stray light problems that were a big nuisance. There were several other aspects of the UC that I did not like. If someone wants an ultra light telescope, I would look at some other options. Ending this on a positive note, I am happy to endorse the Obsession Classic, and I believe it is excellent value for the money. 

there are not that many choices out there when it comes to getting an ultra light or ultra compact scope.  The skywatchers seem to be a big flop from what I can find on the web.   All the other ultra lights I see are made from wood.  I really wanted something made from aluminum or carbon fiber.   The search goes on.




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