Obsession UC Vs Portaball Shootout

[Jagerman Jensen]

Hey folks, so I am considering dropping some serious money on a good set of mirrors and metal and I am in between these two wonderful scopes.

At the moment, the 12.5" Portaball runs at about the same price as the 15" Obsession at roughly ~$5,500 before shipping and whatnot. Now it might seem that aperture would be the immediate deciding factor here, but I wanted to divert our attention to the optics of the two scopes (as well as some other odds and ends).

The Portaball ships with a Zambuto, and the obsession has either Galaxy or OMI. Now its pretty clear that Zambuto is the gold standard without much of a fuss, so we can leave him alone. The real question is, will the obsession provide the same diamond-on-black-velvet images with superb contrast as the Portaball? If the answer is no, then the decision becomes more troublesome since we will be deciding between brightness (Obs) and contrast (PB), as well as the remaining points below.

Second thing on the list is the size of the secondary mirror and the design of the spider legs. The UC has a slightly larger secondary at 2.6" compared to the 2.14" of the PB (correct me if I'm reading the wrong numbers on the site), meaning a possible difference in contrast and FOV in larger eyepieces. The spider in the PB is curved and has two legs, as opposed to the straight 3 legged spider of the UC. I hope someone with experience may chime in on the relevance of those differences to overall optical quality.

Now for the odds and ends:

Speed: The UC is a f/4.5 scope, while the PB is an even f/5. A coma corrector has been recommended for the UC, meaning a possible increase in cost.

Tracking/movement: Although the UC is superbly designed down below, it is quite hard to beat a rotating ball that you can freely manipulate.

Overall design: The UC is, as its name suggests, ultra compact. It will take up less space in a car, and may take more or less time to set-up. I am not sure which one is easier to collimate, so someone will have to clarify. The one big whoop I see in the UC is the shroud doesn't quite cover the primary completely, so if you have an excited friends running up to see your scope they may kick some particles into the mirror. In the greater scheme of things, one can probably make a DIY mirror cover for the exposed parts at the bottom.

I think that just about covers the big points to consider. What I am really looking for with this post is hopefully someone who has tried one or both and can help tip the scales with some experience.

Thanks everyone!

[John]

Hi and welcome to the forum 

I'll be interested to see what feedback you get on this. I suspect that there are a limited number of lucky people who have actually tried either of these, let alone had the opportunity to compare them both. It's always worth asking though  

[Jagerman Jensen]

Thank you John! I agree, asking about two heavy hitters does tighten up the probability, but I look forward to seeing what might come of it

[Daniel-K]

by the obsession and put zambuto mirrors in, problem solved the fact your in a position to buy either makes me sick both of them will be great but if it was me the UC is the way to go.

[crashtestdummy]

For that money I would be looking 20" plus.I'm assuming you are in America?you could get a custom 18" with 1/10pv mirrors over here for less than the price of that obsession and if you are in the UK you could get a 20"+

Aperture does pretty much rule but no point having a massive scope if you can't carry it to your dark site or lift it out of your shed.

[Jagerman Jensen]

by the obsession and put zambuto mirrors in, problem solved the fact your in a position to buy either makes me sick both of them will be great but if it was me the UC is the way to go.

A tittilating idea, but that would drive the price up a bit too high  

For that money I would be looking 20" plus.I'm assuming you are in America?you could get a custom 18" with 1/10pv mirrors over here for less than the price of that obsession and if you are in the UK you could get a 20"+

Aperture does pretty much rule but no point having a massive scope if you can't carry it to your dark site or lift it out of your shed.

Portability is going to be one of the biggest factors in considering which scope I'll get. It should basically be able to fit into a hatchback, so anything over 18" is pushing it unfortunately.

[Dude_with_the_tube]

As you are based in US/Canada,strongly suggest to get yourself to Cloudy Nights classifieds.there you can pick a used scope for less money then you have budgeted so far.

I have to agree with John,there will be very little to none who will be able to give you advise on portaball or obsession as these scopes are very rare here in UK.

Sometimes I wish I lived in US with uK wage lol.

[Dreadz]

For that money I would be looking 20" plus.I'm assuming you are in America?you could get a custom 18" with 1/10pv mirrors over here for less than the price of that obsession and if you are in the UK you could get a 20"+.......

From where might one purchase one of these exceedingly reasonably priced monsters? All the prices ive found been a lot more than £3.5-4K

Sent from my GTi9300 using random spelling mistake generator!!!!

[Jagerman Jensen]

As you are based in US/Canada,strongly suggest to get yourself to Cloudy Nights classifieds.there you can pick a used scope for less money then you have budgeted so far.

I have to agree with John,there will be very little to none who will be able to give you advise on portaball or obsession as these scopes are very rare here in UK.

Sometimes I wish I lived in US with uK wage lol.

Dang you're right, I just checked out the classifieds and they have giants for half price! Time to browse

[crashtestdummy]

From where might one purchase one of these exceedingly reasonably priced monsters? All the prices ive found been a lot more than £3.5-4K

18" luckhurst can be had for £4k

An 18" Sumerian and some mirrors from Nichol optical won't be much over £4k.It's cheaper to get a 20" over here than import a 15" obsession.

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[crashtestdummy]

Damn phone quote grrrrrr

[estwing]

Sumerian and one of johns mirror sounds good!...as said app wins!

[Dreadz]

@crashtestdummy my bad. Had overlooked the classic dobs. Always been looking at the ultra portables which are closer to 5k

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[swamp thing]

Sumerian and one of johns mirror sounds good!...as said app wins!

May prove an expensive option for the OP in Montreal.

Contrast is more down to sky conditions and exit pupil than primary figure. Your not going to get diamonds on velvet from central Montreal no matter how good the mirror. You'll get orange glow with stars. If the sky is good and dark enough any scope will show this sort of diamonds on velvet effect.

I would pick the aperture of the obsession every time. If you want better contrast.....go somewhere darker. Better mirror won't make anywhere near the difference the sky you observe from will.

Good luck picking a scope, they're both winners IMO

[jetstream]

I have heard the portaball scopes are great,but care must be taken not to damage or scratch the "ball".The conventional Obsession Classic may be more forgiving in this regard(handling),I'm looking for a 15"-18" too.CN classifieds have listed 18" Obsessions that have gone for $3500-$4000 with good mirrors.Good luck with your hunt!

[Jagerman Jensen]

May prove an expensive option for the OP in Montreal.

Contrast is more down to sky conditions and exit pupil than primary figure. Your not going to get diamonds on velvet from central Montreal no matter how good the mirror. You'll get orange glow with stars. If the sky is good and dark enough any scope will show this sort of diamonds on velvet effect.

I would pick the aperture of the obsession every time. If you want better contrast.....go somewhere darker. Better mirror won't make anywhere near the difference the sky you observe from will.

Good luck picking a scope, they're both winners IMO

Right you are! I wouldn't dream of pointing a cannon at anything but the moon and planets in the city Just a few hours drive though is Mont Megantic, which has some reasonably dark skies (Darkest around here anyway). If I'm going fuzzy hunting it will be there for sure.

In a year or two though I'd like to relocate to Hawaii and take advantage of the darkest skies around, which is partly why I'm trying to get a-hold of a nice piece of equipment.

On another note though, does anyone know if the Obsession UC has the possibility of a motorized mount? I know the classics support it, but it gets muddy when I try searching for the UC.

Thanks everyone!

[crashtestdummy]

If by motorised you mean encoders for alt and az then yes they can be fitted,if you mean a full mount like a HEQ6 then probably not

[Jagerman Jensen]

If by motorised you mean encoders for alt and az then yes they can be fitted,if you mean a full mount like a HEQ6 then probably not

Yeah HEQ6 is pretty extremo for this setup. I asked out of interest for astrophotography, since it would be pretty cool to use the UC for getting some awesome pictures. If the UC doesn't support photography very well, its no biggie. I think general star gazing will hold me over until I buy a bigger scope that can support tracking

[Dreadz]

Yeah HEQ6 is pretty extremo for this setup. I asked out of interest for astrophotography, since it would be pretty cool to use the UC for getting some awesome pictures. If the UC doesn't support photography very well, its no biggie. I think general star gazing will hold me over until I buy a bigger scope that can support tracking

Even with servocat fitted for tracking a dob isnt going to work for AP for anything other than lunar and maybe planetary at a push. AP really needs an eq mount.

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[Jagerman Jensen]

Even with servocat fitted for tracking a dob isnt going to work for AP for anything other than lunar and maybe planetary at a push. AP really needs an eq mount.

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Thanks for clarifying Dreadz, looks like I'll be buying two scopes eventually after all