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Mass Produced Donsonian Optics

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#1 10001110101

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Posted 17 October 2018 - 06:08 PM

Out of the mass produced dobsonian scopes out there, which optics do you trust the most? 

Explore Scientific (JOC)

Orion (Synta)

Apertura/Zhumell (GSO)

Meade (Who makes Meades?)

 

Am I missing any affordable makers?

 

Any I should avoid?

 

I'm considering buying a 12 in dobsonian, but i'm not ready to jump into to the high end stuff yet. Just want the best value for optics for now.


Edited by 10001110101, 17 October 2018 - 06:16 PM.


#2 TOMDEY

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Posted 17 October 2018 - 06:49 PM

I guess this is worth mentioning here, regarding selection of mirrors for fastish Newt telescopes.

 

I had commissioned the JMI RB-16 binoculars several years ago. An optional upgrade was to provide one's own 16-inch mirrors. I noticed that the "stock" mirrors appear to be GSO 16" F/4.5 with folding flat... both BK7 coated with Al+overcoat. JMI also sells the mirrors separately, at the astoundingly affordable price of $1460 for coated 16" PM and folding flat. Wow! But I was wary of spending "only" $2900 on the mirrors going into a $14K binoscope!

 

So, I did the upgrade and got custom-matched Borosilicate mirrors from Normand Fullum. And also got Enhanced Aluminum coatings from OWL. And superior tertiary (star diagonal) folds provided by JMI at some added cost.

 

With other optionals (encoders, NGC-MAX computer, etc.) total cost, to me, came in somewhere around $20K.

 

But ... the performance is MAGNIFICENT! ... as I KNEW it would be.

 

What I'm saying, if you have decided to go cheap on mirrors, you can Hope that performance will be wonderful... but probably expect/accept ... that it will leave something to be desired.

 

Gota admit, long ago, I had the Coulter 13.1", then 17.5" and then their 29"... and they were GREAT! ... for the price. Cheap Light Buckets, but a pleasure to use!

 

No right answer: Cheap is usually worth it, expensive is usually worth it.  Tom


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#3 The Ardent

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Posted 17 October 2018 - 06:53 PM

The best value is finding one in the classifieds. 



#4 10001110101

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Posted 17 October 2018 - 07:41 PM

The best value is finding one in the classifieds. 

I've been scanning for a 12 in to pop up close by, but should I focus on looking for one brand over another?



#5 The Ardent

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Posted 17 October 2018 - 07:48 PM

No, not really. These mirrors are mostly interchangeable. Some will be good and some not, most will be ok.

Scopes: Look for features and how well taken care of. A lot of 12” scopes get used once and then sit unused because of size and weight.

Used ones offen include extra accessories that may cost more than the scope if purchased new.

Good luck!

#6 Pinbout

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Posted 17 October 2018 - 08:00 PM

Out of the mass produced dobsonian scopes out there, which optics do you trust the most? 

Explore Scientific (JOC)

Orion (Synta)

Apertura/Zhumell (GSO)

Meade (Who makes Meades?)

 

Am I missing any affordable makers?

 

Any I should avoid?

 

I'm considering buying a 12 in dobsonian, but i'm not ready to jump into to the high end stuff yet. Just want the best value for optics for now.

I do not trust any,

 

but I have some that are pretty good,

 

see a lot of  *&%,

 

but most 2ndry's are @#^%


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#7 barbie

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Posted 17 October 2018 - 10:14 PM

The primary AND secondary in my 6" F8 Orion synta are excellent.  High powers on the planets are easily achieved and they both tested to be excellent on the bench.


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#8 havasman

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Posted 17 October 2018 - 10:51 PM

​I had the primary in my Orion XT10i tested and it is actually quite good enough. In my experience, none of the mass market secondaries are much worth a tinker's **** and the best bang for the buck mod optically is replacing the secondary. A friend of mine replaced his 12" Orion primary with a Zambuto and later replaced his secondary with an Antares and the verdict was that the secondary made more difference.

Since you asked, my opinion is that of the 4 your listed, go with the Orion or Apertura. A past club president downsized to an Orion XX12g that I have observed with a few times and it is very good, completely stock and breaks down into a handy package.


Edited by havasman, 17 October 2018 - 10:53 PM.

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#9 Jond105

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Posted 17 October 2018 - 10:57 PM

I think my synta 10" views are quite good like havasman. I've looked at Antares secondaries as well, just haven't felt the need yet to make the replacement as I've only had it a little over 2 months.

Edited by Jond105, 17 October 2018 - 10:57 PM.

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#10 Smug

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Posted 18 October 2018 - 12:13 AM

I don't think modern mass produced optics tend to have a massive variation these days. At the very least quality control has gotten better in the past few years. I tend to favour Synta (skywatcher) because all of their scopes (4 at this point) I have owned have performed well optically. My issues with them are the manual dob base which is awful for high powered tracking, and the cheap standard focusers. The GOTO dobs are good though.


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#11 tphili1959

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Posted 18 October 2018 - 03:03 AM

i have an orion and a skywatcher dob.  both mirrors seem  equally great visually.  from what i have heard, both  scopes mirrors are made by synta.


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#12 Eddgie

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Posted 18 October 2018 - 10:06 AM

I can't speak for the other brands, but I purchased an Orion 12" scope about 5 years ago.  I had budgeted enough to have the mirror re-figured because I wanted it to be capable of really excellent planetary performace.

 

Much to my delight, the mirror that came in the scope was far better than I had expected.  I do a lot of star testing using Suiter's methods, and here is what I found: No turned edge, no zones, and while not premium level of smoothness, still surprisingly good.   A 33% obstruction test for spherical aberration was almost perfect.  At 10 waves of defocus, it was almost impossible to see any size difference in the secondary shadow size and the breakout was to close on either side to be easy to see.   I was very impressed with the quality and decided that there would be little practical improvement to be made by sending it to someone for re-figuring.  

 

Planetary views with this scope are spectacular.   Side by side, my 6" Apo really could not keep pace, and in fact, I had better Jupiter views in this scope than in my C14 (which was not a bad C14, but not of the same quality as the Orion).

 

This is not a premium quality mirror, but it is quite excellent. 

 

I don't know if this is typical or if I got lucky, but this telescope gives the best planetary views I have ever had.  


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#13 Adun

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Posted 18 October 2018 - 10:42 AM

Scopes: Celestron 114az, Orion 127mm Mak-Cass,  Celestron C6, Zhumell Z8

Mounts: Orion Starseeker IV, Orion EQ-1, Celestron Alt/Az, Dob 8"

EP's: Meade 5000 5.5 & 8.8mm UWA, Svbony 9mm 66*, Televue 11mm Nagler, Zhummel & Celestron Omni 12mm Plossl, Svbony 10 & 23mm Aspheric 62*, Celestron 25mm E-Lux, Celestron 8-24mm zoom, Baader 8-24mm Zoom, Zhummel 2" 30mm

Barlow's: GSO 2x, Baader 2.25x

Accesories: Telrad, 5 & 6 inch Astrozap Dew Sheild's, Red dot finders, Orion Narrowband Filter, Moon Filter, Celestron F/6.3 Reduce, 9x50 RACI, 6x30 finder, Celestron Red Flashlight, Several books & Sky Maps

 

You own the Meade 5.5 and 8.8 UWAs (great value), a 9mm expanse clone, the two "good" 62º aspherics (but not the 4mm), and a single Nagler 11mm (No Ethos, Delos, etc). Your choice of Narrowband Filter was Orion's

 

My take is you are more value oriented, wary of "cheap stuff means buying twice" but also unwilling to splurge on alleged pixie dust.

 

I'm also guessing your main motivation driver is want of an aperture upgrade from your Z8, which would be why you're skipping the 10" size. So you'll be going from F6 to under F5, so collimation and coma will be more paramount than in your Z8. 

 

I've heard bad things about Meade mirrors from a mirror maker I know. Explore Scientific dobs are rather new, I haven't heard much about them. So I'd stick with GSO and Synta (Zhumell/Apertura, Orion/Skywatcher).

 

Optical quality will at the same time be "ensured" in the sense that the optics made by these manufacturers is reputed to be "good enough", but at the same time will be a roulette (you might get a lemon, or a peach).

 

Anyway, my advise is, stick to Synta/GSO and go either for "whatever shows up used" to save the most $$, or choose based on the other non-optics details, such as focuser, weight, solid vs collapsible vs truss, bearings vs pads, transportability, etc.

 

If "value for optics" concerns you so much, and (like me) you can't afford premium mirrors, you might want to consider adding a coma corrector to your budget equation. Those can be cumbersome, but at F4.8 they improve the optics quite some.

 

Also, although you don't seem to do any imaging (please forgive me for suggesting this) if your want of aperture is to be able to see stuff your Z8 isn't showing you, be aware that your Celestron 114 OTA mounted on your Starseeker IV mount could show you more than a 12" dob could, if you bought a proper EAA camera for it.


Edited by Adun, 18 October 2018 - 10:44 AM.

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#14 Muddman97

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Posted 18 October 2018 - 10:48 AM

The primary on my 10 inch Zhumell (aka Apertura) is very good as far as I can tell through a star test.  I'm sending it off to Steve Swayze soon for legit testing but I think it will fair just fine.

 

I will also be replacing my secondary with a 1/20 wave Antares, not even going to bother testing it, just replace it.


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#15 10001110101

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Posted 18 October 2018 - 01:16 PM

You own the Meade 5.5 and 8.8 UWAs (great value), a 9mm expanse clone, the two "good" 62º aspherics (but not the 4mm), and a single Nagler 11mm (No Ethos, Delos, etc). Your choice of Narrowband Filter was Orion's

 

My take is you are more value oriented, wary of "cheap stuff means buying twice" but also unwilling to splurge on alleged pixie dust.

 

I'm also guessing your main motivation driver is want of an aperture upgrade from your Z8, which would be why you're skipping the 10" size. So you'll be going from F6 to under F5, so collimation and coma will be more paramount than in your Z8. 

 

I've heard bad things about Meade mirrors from a mirror maker I know. Explore Scientific dobs are rather new, I haven't heard much about them. So I'd stick with GSO and Synta (Zhumell/Apertura, Orion/Skywatcher).

 

Optical quality will at the same time be "ensured" in the sense that the optics made by these manufacturers is reputed to be "good enough", but at the same time will be a roulette (you might get a lemon, or a peach).

 

Anyway, my advise is, stick to Synta/GSO and go either for "whatever shows up used" to save the most $$, or choose based on the other non-optics details, such as focuser, weight, solid vs collapsible vs truss, bearings vs pads, transportability, etc.

 

If "value for optics" concerns you so much, and (like me) you can't afford premium mirrors, you might want to consider adding a coma corrector to your budget equation. Those can be cumbersome, but at F4.8 they improve the optics quite some.

 

Also, although you don't seem to do any imaging (please forgive me for suggesting this) if your want of aperture is to be able to see stuff your Z8 isn't showing you, be aware that your Celestron 114 OTA mounted on your Starseeker IV mount could show you more than a 12" dob could, if you bought a proper EAA camera for it.

That pretty much sums up what I'm looking for (good assessment). Best bang for the buck - I'm not looking to spend three times the money for only a 5% improvement. I've been trying to get the hang of visual observing, but wouldn't mind getting into EAA, but i hear it is costly? What all do you need to get setup? Camera recommendations?



#16 Old Rookie

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Posted 18 October 2018 - 01:19 PM

I had the mirror from my Apertura 12AD tested when i converted it to a three strut.  I was pleasantly surprised to find out it was an excellent mirror that didn't need any work period.


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#17 10001110101

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Posted 18 October 2018 - 01:21 PM

The primary on my 10 inch Zhumell (aka Apertura) is very good as far as I can tell through a star test.  I'm sending it off to Steve Swayze soon for legit testing but I think it will fair just fine.

 

I will also be replacing my secondary with a 1/20 wave Antares, not even going to bother testing it, just replace it.

My Z8 produces good images, at least as far as I can tell. That's the intial direction my gut told to go was another Zhumell/Apertura, but another opportunity just opened up. 


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#18 Adun

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Posted 18 October 2018 - 02:40 PM

That pretty much sums up what I'm looking for (good assessment). Best bang for the buck - I'm not looking to spend three times the money for only a 5% improvement. I've been trying to get the hang of visual observing, but wouldn't mind getting into EAA, but i hear it is costly? What all do you need to get setup? Camera recommendations?

 

If you live under or have easy access to darker skies (say: yellow or better), then a 125% aperture increase from 8" to 12" is perhaps worth it.

 

But if you are in a city, and your skies show orange or worse on maps, then you're at risk of still being left wanting despite the upgrade. I live in a city, red on the maps (bortle 8+) and my 10" dob is my least used scope because of it. 

 

Astrophotography is very costly, but EAA not so much. Many people do it on alt-az goto mounts (like a Nexstar SE, my Starblast autotracker, or your Starseeker IV). It needs a short fast scope (some people use expensive APOs, but many use short reflectors, I use a 114mm F4). Then for the camera there are a two choices:

 

  • For those without a computer (or who prefer to not deal with one), there's the Revolution Imager 2 (an analog camera with output video cable that goes to a 7" screen)
  • For those with a laptop (or who prefer the benefits of saving snapshots to share/remember) there are the ASI224 ($250) and ASI385 ($400), the latter offering a larger sensor (50% larger field of view) but both being used and liked.

 

If your 114mm Celestron reflector is F4, in good condition, and you can mount it in your Starseeker goto mount, then a $250 investment on an ASI224 would show you fainter DSOs (and with a lot more more detail) than a 12" dob would. 


Edited by Adun, 18 October 2018 - 02:41 PM.

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#19 10001110101

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Posted 18 October 2018 - 03:29 PM

If you live under or have easy access to darker skies (say: yellow or better), then a 125% aperture increase from 8" to 12" is perhaps worth it.

 

But if you are in a city, and your skies show orange or worse on maps, then you're at risk of still being left wanting despite the upgrade. I live in a city, red on the maps (bortle 8+) and my 10" dob is my least used scope because of it. 

 

Astrophotography is very costly, but EAA not so much. Many people do it on alt-az goto mounts (like a Nexstar SE, my Starblast autotracker, or your Starseeker IV). It needs a short fast scope (some people use expensive APOs, but many use short reflectors, I use a 114mm F4). Then for the camera there are a two choices:

 

  • For those without a computer (or who prefer to not deal with one), there's the Revolution Imager 2 (an analog camera with output video cable that goes to a 7" screen)
  • For those with a laptop (or who prefer the benefits of saving snapshots to share/remember) there are the ASI224 ($250) and ASI385 ($400), the latter offering a larger sensor (50% larger field of view) but both being used and liked.

 

If your 114mm Celestron reflector is F4, in good condition, and you can mount it in your Starseeker goto mount, then a $250 investment on an ASI224 would show you fainter DSOs (and with a lot more more detail) than a 12" dob would. 

My home location is Bortle class 4 - 21.25 SQM. With easy access to Class 3 - SQM 21.72. 

 

My 114 is a Jones-Bird design so it's an F9 with optics on the lower end. 

 

https://www.celestro...114az-telescope

 

My Mak and SCT are probably a little to fast, but I have an F6.3 reducer for the SCT. I could get an eq platform at some point for a dob.


Edited by 10001110101, 18 October 2018 - 03:29 PM.


#20 Adun

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Posted 18 October 2018 - 04:24 PM

My home location is Bortle class 4 - 21.25 SQM. With easy access to Class 3 - SQM 21.72. 

 

My 114 is a Jones-Bird design so it's an F9 with optics on the lower end. 

 

https://www.celestro...114az-telescope

 

My Mak and SCT are probably a little to fast, but I have an F6.3 reducer for the SCT. I could get an eq platform at some point for a dob.

 

Ah Bortle 4 skies, that must be sweet. I have to get on an airplane to get to Bortle 3. For your skies, a 12" upgrade might as well be the better idea. 

 

Since your 114 reflector is F9, it won't do for EAA. And getting started on imaging/EAA with an SCT/Mak is really discouraged. Even with an F6.3 reducer a C6 (I own one) ends up with 945mm FL which is quite long for imaging, demands better tracking, limits you to the smallest DSOs (galaxies and small planetaries). People who do EAA with SCTs like hyperstar (expensive but F2) or the F3.3 reducers, but those comes with their own complexities which are best avoided when learning imaging.

 

So, back to the dob upgrade, all the advise I can give is:

 

Consider your transportation needs for getting a larger dob to those Class 3 skies you have easy access to. If you own a truck you can have anything, but on a sedan, a solid tube 12" may not fit. if that's the case (or you want to drive with a passenger) then consider a collapsible skywatcher or a truss Explore Scientific.

 

If solid tube is ok, then you're probably best hunting the classifieds for a while until the best deal shows up.



#21 Don H

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Posted 18 October 2018 - 04:30 PM

There is a 12 inch in Indianapolis for sale in the classifieds for 300. It seems like your skies might benefit from a 12, but you might want to hold out for a truss Dob, even though it would cost a whole lot more...



#22 Starman1

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Posted 18 October 2018 - 05:14 PM

Meade mirrors are GSO.

 

You forgot SkyWatcher, which is another Synta brand.

 

The focusers on the Meades, Aperturas, and Explore Scientifics are better than the Orions and Sky-Watchers, IMO.

Smoother and more easily adjusted and easier to use.

 

The mirror cells on all of the scopes are decent in 10" and larger.

 

As for movement on the axes, I favor the Explore Scientifics, since they have borrowed from high end scopes.

And this is true whether you get a tubed or truss version.

 

The Explore Scientifics also allow placement of the focuser on either side, whatever your preference.

 

As far as performance, goes, all are made in a bell-shaped curve.  Your odds are good to get a halfway decent mirror, but your odds are low that you will get either a complete dog or a superb mirror.

(the best 16" mirror I've ever seen was a GSO, BTW).

 

Look for fans standard and as thin a mirror as possible.  Those are factors that will influence the ability to see clearly and sharply early in the night instead of 3 to 4 hours later.


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#23 10001110101

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Posted 18 October 2018 - 05:53 PM

There is a 12 inch in Indianapolis for sale in the classifieds for 300. It seems like your skies might benefit from a 12, but you might want to hold out for a truss Dob, even though it would cost a whole lot more...


I saw that, too far away and no shipping. Good deal though.

Edited by 10001110101, 18 October 2018 - 05:54 PM.


#24 10001110101

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Posted 19 October 2018 - 09:43 AM

Meade mirrors are GSO.

 

You forgot SkyWatcher, which is another Synta brand.

 

The focusers on the Meades, Aperturas, and Explore Scientifics are better than the Orions and Sky-Watchers, IMO.

Smoother and more easily adjusted and easier to use.

 

The mirror cells on all of the scopes are decent in 10" and larger.

 

As for movement on the axes, I favor the Explore Scientifics, since they have borrowed from high end scopes.

And this is true whether you get a tubed or truss version.

 

The Explore Scientifics also allow placement of the focuser on either side, whatever your preference.

 

As far as performance, goes, all are made in a bell-shaped curve.  Your odds are good to get a halfway decent mirror, but your odds are low that you will get either a complete dog or a superb mirror.

(the best 16" mirror I've ever seen was a GSO, BTW).

 

Look for fans standard and as thin a mirror as possible.  Those are factors that will influence the ability to see clearly and sharply early in the night instead of 3 to 4 hours later.

Thanks, you always have the best info. I can't recall seeing mirror thickness listed in the specs anywhere. Is there a website that list this info?



#25 Starman1

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Posted 19 October 2018 - 09:47 AM

Other than seeing mirror thickness mentioned in an occasional post, I'd simply call or email and ask.

Most of the companies will tell you.




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