119 replies to this topic

[Astrojedi]

That's just it, dobs/reflectors are a bottomless pit.  You have to buy a Paracorr, which isn't cheap.  And then fiddle with it for different eyepieces and depending on the eyepiece and reflector you probably have to add counterweights.  Then there are the cheshires and lasers and fans you have to buy.  If you have a truss there's a shroud.  If it's a big, heavy dob, i.e. 12-14 inches you have to buy wheels to move it around.  Like I said, they're bottomless pits and not nearly the bargain they're made out to be.

Still cheaper than a 14” Apo... or a 12” Apo... or a 10” Apo... or a 8” apo... 

Edited by Astrojedi, 26 July 2018 - 11:15 AM.

[Astrojedi]

And don’t get me wrong. I love my refractors and spend gobs of money acquiring them. The views have a certain intangible quality and in smaller apertures they are incredibly easy to use. But larger apertures bring capabilities that small apertures don’t.

 

To me this debate is not really about frac vs. dob... it is really small aperture vs. large aperture.

[CounterWeight]

A few years back I compared my TEC 160ED to my 14" XXg Dob/Newt, my experience was that 'planetary included' (I think Saturn was mostly used), as the seeing improved, the 14" started easily / obviously pulling ahead.  Is not often we get seeing good enough for that, but the difference was obvious to my eyes, and you can see which one was sold.

[Astrojedi]

I find this a very dubious argument for a couple of reasons:

 

1. Even in average seeing a 14" scope will perform better on deep sky and go significantly deeper than a 6" scope (note the design is irrelevant - frac or newt). Planets will also see some improvement.

 

2. Secondly, using this argument no one should buy even 6" refractors as the seeing will not support their full resolution. We should all use 100mm refractors and call it a day.

 

In my experience a larger aperture helps in all conditions. But that does not mean I recommend a large aperture scope to everyone. The ultimate choice is driven by personal preferences (convenience, observing style etc.). I am only trying to offer pros and cons of each here. Only the Op can decide what is right for him.

Edited by Astrojedi, 26 July 2018 - 02:25 PM.

[Chesterguy1]

Is anyone, including the OP, truly cross-shopping these two scopes?  While there are some opportunities for overlap, I will take my Obsession 15” every night, with the caveat that it takes time for the mirror to acclimate and the set up and collimating requires additional time/effort.  I’m content with my 8” reflector most nights.  I do like my refractor better on doubles, but the 15” and 8” will split tighter ones.  Incidentally, my seeing is not great, but I have excellent transparency and minimal cloud cover most nights and my focus is typically on DSOs and there is NO CONTEST.

 

Rare indeed is the night when using my 15” that I say, gee, I wish I would have brought out the 120mm—or even the 8”, which has a fantastic mirror, and curved vanes.  Possibly, only when the session had to be curtailed early because clouds rolled in.  With the 120mm I’m frequently saying to myself, boy, that would be better with my reflectors.  The exception might be on nights when I want wide views or merely to surf the MW.

 

Get a used quality big reflector and a less expensive, but still quite capable doublet refractor and never look back.

 

Gogiboy

Edited by Chesterguy1, 26 July 2018 - 04:24 PM.

[CHASLX200]

I get a lot of nites with no seeing. I usually stay inside.

No seeing meant it was like being in space. As there was no seeing as in it was dead still.

[CHASLX200]

That's just it, dobs/reflectors are a bottomless pit.  You have to buy a Paracorr, which isn't cheap.  And then fiddle with it for different eyepieces and depending on the eyepiece and reflector you probably have to add counterweights.  Then there are the cheshires and lasers and fans you have to buy.  If you have a truss there's a shroud.  If it's a big, heavy dob, i.e. 12-14 inches you have to buy wheels to move it around.  Like I said, they're bottomless pits and not nearly the bargain they're made out to be.

I only used the older style Paracorr and never had to fool with anything. I just plopped in Radians and Nags in my Zambuto and OMI scopes and had insane views coma free at 700 to 1150x.

[starman876]

this thread remains a constant source of amusement

[RAKing]

this thread remains a constant source of amusement

Beats watching TV reruns. 

[noisejammer]

That's just it, dobs/reflectors are a bottomless pit.  You have to buy a Paracorr, which isn't cheap.  And then fiddle with it for different eyepieces and depending on the eyepiece and reflector you probably have to add counterweights.  Then there are the cheshires and lasers and fans you have to buy.  If you have a truss there's a shroud.  If it's a big, heavy dob, i.e. 12-14 inches you have to buy wheels to move it around.  Like I said, they're bottomless pits and not nearly the bargain they're made out to be.

You, sir have never entered the realm of Takahashi ... penury by a thousand adapters...

 

Seriously - my Tak needed rings & dovetail, a finder and illuminator, a finder stalk, a quick release, a new focuser, extension tubes, corrector, extender, compressor, 2" adapter, diagonal, Herschel wedge, binoviewers, dozens of eyepieces, a transport case and a few other odds and ends.

 

Dob owners have it easy.

[dr.who]

So very true. Both the entertainment value of the thread and what Bruce said about death by adapter courtesy of Tak.

[jag32]

Hi everyone. As the thread starter I wanted to let everyone know I've decided to go with a big dob. I am considering the Obsession Ultra Compact 22" with go-to, which is roughly the same cost as a TOA150 mounted on an EM400.

[dr.who]

What about a Teeter sub f/4 with the same GOTO setup? Will likely mean you can keep your feet on the ground when observing and get a thinner mirror.

[CHASLX200]

Beats watching TV reruns. 

naw, SPACE1999 is better and bigger.

[jag32]

What about a Teeter sub f/4 with the same GOTO setup? Will likely mean you can keep your feet on the ground when observing and get a thinner mirror.

What is the advantage of a thinner mirror?

 

Personally the all aluminum design of the Obsession UC is more attractive to me than the classic looking wooden Dobs. But if I am sacrificing performance I would go for a wooden Dob from Teeter or New Moon instead.  I do have the opportunity to buy a used but still brand new Obsession UC 22 for only 9k with go-to, which is actually worth about 16k from Obsession. 

Edited by jag32, 26 July 2018 - 07:49 PM.

[CHASLX200]

What is the advantage of a thinner mirror?

 

Personally the all aluminum design of the Obsession UC is more attractive to me than the classic looking wooden Dobs. But if I am sacrificing performance I would go for a wooden Dob from Teeter or New Moon instead.  I do have the opportunity to buy a used but still brand new Obsession UC 22 for only 9k with go-to, which is actually worth about 16k from Obsession. 

Thinner mirror cools faster and weighs less. But you need better mirror support for thinner mirrors.

[starman876]

 i would go with an ultra light and have something you can handle without breaking your back.  The ultra lights also come with go to.

 

Have been seriously trying one.

 

I have a 12" newt made from carbon fiber that weighs 28 lbs.  

 

 

 

 

Edited by starman876, 26 July 2018 - 09:01 PM.

[CounterWeight]

 

I find this a very dubious argument for a couple of reasons:

 

1. Even in average seeing a 14" scope will perform better on deep sky and go significantly deeper than a 6" scope (note the design is irrelevant - frac or newt). Planets will also see some improvement.

 

2. Secondly, using this argument no one should buy even 6" refractors as the seeing will not support their full resolution. We should all use 100mm refractors and call it a day.

 

In my experience a larger aperture helps in all conditions. But that does not mean I recommend a large aperture scope to everyone. The ultimate choice is driven by personal preferences (convenience, observing style etc.). I am only trying to offer pros and cons of each here. Only the Op can decide what is right for him.

Merely stating my experience, not  attempt to form an argument.  Specific to the 6" apo and newt question asked, I have done it, and after a good amount of time that was the result I arrived at, for me. 

 

I'd still have the TEC if I could afford it as I am also a fan of refractor views. Of course on globulars aperture always cleanly wins... but then if you want very wide a small refractor is pretty ideal, if not binoculars.   To me there is no 'best' always.  There is a lot out there that is at least very good IMO a lot of time if used within it's brackets. 

 

A contrary POV would be that it took rare very good seeing for the newt to strut it's stuff for planetary while the 6" apo was always nice to view them with.

 

Throw money and not science or experience and location into the picture and it changes entirely for most folks, me included.   For me we are in a modern golden age for amature astronomy.  That someone could own both new for under $10k today, and get a mount for the refractor... is really to me impressive!

 

With the arrival of somewhat affordable large refractors for visual by that I mean ~150mm SW, TS, AT, APM, there are a lot of folks that can now at least try it for themselves for a fraction of the cost 10 yrs. ago. Goto Dob's a fraction of what it cost 10 years ago.  Then there are all the other designs...  imaging, video assisted, NV ...  the times they are a changing!

 

I agree too that information on the web is not experience that can be somehow absorbed as it is the individuals experience that is the only yardstick.  Did not mean to misrepresent anything. 

 

So folks should buy stuff and get out and use it.  then go to the eyepiece forum and ask about best eyepiece...

[Kunama]

I am glad the OP made a decision, now we can all look forward to the next Apples vs Oranges thread... 

 

I wish the word "versus" had never been invented..... 

 

To me this hobby is still a "Three scope" one, people trying to find the one scope to rule them all will end up spending a fortune trying to find an answer.....

Everyone needs a small refractor, a pair of decent binoculars and a big light bucket for the faint stuff.

 

As for planetary views, in nearly 50 years of staring at the night sky, my best ever view of Saturn was not with a Dob, nor with binoculars or a refractor, but a TEC Maksutov Cassegrain, talk about seller's remorse......

Edited by Kunama, 26 July 2018 - 10:04 PM.

[nicoledoula]

Which one is ready to use quicker? Which one shows stars as points? Of course one sees more planetary detail IF conditions allow.   Saturn looked great because conditions allowed. It would have looked better in an equal sized APO  And DO NOT ask about EP's on the EP forum. Not until after you've read the whole thing. Seriously. 

Edited by nicoledoula, 26 July 2018 - 10:09 PM.

[Astrojedi]

 

 

To me this hobby is still a "Three scope" one, people trying to find the one scope to rule them all will end up spending a fortune trying to find an answer.....

Everyone needs a small refractor, a pair of decent binoculars and a big light bucket for the faint stuff.

 

 

Very true... I don’t think I could do without my refractors or my dob. Just apples and oranges.

[nicoledoula]

LOL, it took a 22" obsession with goto to beat a 6" APO. That's how I'm going to construe it anyway. HA

[Kunama]

Which one is ready to use quicker? Which one shows stars as points? Of course one sees more planetary detail IF conditions allow.   Saturn looked great because conditions allowed. It would have looked better in an equal sized APO  And DO NOT ask about EP's on the EP forum. Not until after you've read the whole thing. Seriously. 

All apos are not created equal, I have looked through many scopes labelled as "apo" that were far more chromatic than apochromatic......

[Tyson M]

 

 

As for planetary views, in nearly 50 years of staring at the night sky, my best ever view of Saturn was not with a Dob, nor with binoculars or a refractor, but a TEC Maksutov Cassegrain, talk about seller's remorse......

Those scopes are rarer than hen's teeth.....no more Intes Micro as well.  Large MCT's are few and far between unless getting a monster one from APM

[gnowellsct]

I find this a very dubious argument for a couple of reasons:

 

 

 

2. Secondly, using this argument no one should buy even 6" refractors as the seeing will not support their full resolution. We should all use 100mm refractors and call it a day.

 

 

No we should all be using 60 mm stopped down to 40 mm.  That would show that nasty ol' bad seeing.  

 

I agree with you about aperture.  I've been using EDs and apos paired with each other (such as 81 mm on 130 mm) and on larger instruments (81 and 102 on c8 and c14) and have yet to come away thinking:  "Thank God I have this here four inch refractor to save the night's planet viewing."    The aperture always wins.  On SCTs I amend the concept, I think the common wisdom that one subtract the diameter of the CO to get the equivalent apo diameter is a good rule of thumb.  But even so the bigger scope can deliver more color saturation and more deep sky.  

 

But as I have already posted, the reason to get a 6 or 8 inch apo is because you're an incurable apo nut.  I don't see why anyone would want to argue with that.  Furthermore these expensive scopes funnel income to some very interesting and talented people who add some depth and knowhow to our north american astronomy community.  It's good all around.

 

Greg N