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Mass Produced Donsonian Optics

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#26 10001110101

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Posted 19 October 2018 - 09:47 AM

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.

Thanks for the info Adun, In the future I may look into getting a imaging scope for my goto mount. I have a Chevy Silverado so I can just about anything solid or truss haha.



#27 fatrowbridge

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Posted 20 October 2018 - 02:40 PM

GEO mirror thickness  http://www.gs-telesc...tent.asp?id=142


Edited by fatrowbridge, 20 October 2018 - 02:44 PM.

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#28 dongallo

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Posted 21 October 2018 - 10:03 AM

It's no longer the 80's and 90's where mass produced mirrors were hit or miss. Now days and it has been like this for the past 15 years, Synta and GSO mirrors are of good quality. They have high tech factories that can pump out consistent quality mirrors. The mirrors are fantastic optically and anyone would be proud to own one. These two companies have revolutionized amateur astronomy. Now you can buy an affordable telescope with optics you can trust.

Are they as good as premium optics. No, but you will have to know your stuff and look hard to tell the difference. The mechanics and motions of premium scopes are larger advantages than optics verse mass produced.

Now in our hobby we have a choice between great and excellent. Junk and risk has largely been eliminated from the market. 


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#29 barbie

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Posted 21 October 2018 - 01:03 PM

I owned a premium scope and a mass produced scope at the same time and compared the two side by side and saw no differences in mechanical or optical quality, period.  That was twelve years ago BTW and the mass produced scopes by Synta and GSO have only gotten better.


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#30 Starman1

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Posted 21 October 2018 - 04:56 PM

I owned a premium scope and a mass produced scope at the same time and compared the two side by side and saw no differences in mechanical or optical quality, period.  That was twelve years ago BTW and the mass produced scopes by Synta and GSO have only gotten better.

Seriously?

No improvement in the mirror cell, focuser, altitude or azimuth movement and balance, stiffness in the structure, finish and materials of the base,

contrast enhancement by control of light scatter, optical quality at high power, cooling, or ease of collimation?

I saw all of those improvements when comparing a bare bones Discovery (not a particularly high-end scope) with a similarly-sized Orion XT.

There was, of course, more than a 2:1 difference in price at the time, so easy to understand.  But the improvements were fairly major and easily seen.

That you might not see a difference in optical quality is serendipitous.  That you saw no difference in construction quality of the scope is somewhat hard to believe.


Edited by Starman1, 21 October 2018 - 04:57 PM.

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#31 EJN

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Posted 21 October 2018 - 05:21 PM

Do we really need like 500 threads on this topic? BeatingADeadHorse.gif



#32 barbie

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Posted 21 October 2018 - 10:29 PM

Second thumbs up for the Moonlite.  I have a Moonlite on my 120mm refractor and it’s silky smooth.  I have a Feathertouch focuser on each of my dobs—hard to beat.  My first dob had a single speed crayford focuser, which at the time was a definite upgrade.  They have been superseded by newer designs. The quality (smoothness) of the focuser becomes more important when using manual or push-to scopes on higher mag targets.  Practice doesn’t hurt either.

 

Chesterguy

 


Seriously?

No improvement in the mirror cell, focuser, altitude or azimuth movement and balance, stiffness in the structure, finish and materials of the base,

contrast enhancement by control of light scatter, optical quality at high power, cooling, or ease of collimation?

I saw all of those improvements when comparing a bare bones Discovery (not a particularly high-end scope) with a similarly-sized Orion XT.

There was, of course, more than a 2:1 difference in price at the time, so easy to understand.  But the improvements were fairly major and easily seen.

That you might not see a difference in optical quality is serendipitous.  That you saw no difference in construction quality of the scope is somewhat hard to believe.

That's right!!  I had a Cave Astrola 10" F8 and a GSO 10 " F5 side by side and they both stood up well to high magnification on the planets.  No serendipity here, just extensive testing.  Perhaps your predjudice towards premium scopes has clouded your vision!!  I also had a chance to directly compare an Orion 10" XT to a Zambuto of similar aperture and they BOTH showed the same amount of detail in Jupiter's cloud bands at similar magnifications.  Both were properly cooled and collimated and both seemed to have good mechanical construction that didn't interfere with high magnification planetary performance so Yes, I would say the mass produced scopes have gotten a lot better.grin.gif  You and others on this forum have the  attitude that a scope has to be premium to deliver outstanding image quality and that simply isn't the case!!

Now we can consider this horse sufficiently beaten to death!!lol.gif lol.gif lol.gif


Edited by barbie, 21 October 2018 - 11:06 PM.


#33 Pinbout

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Posted 22 October 2018 - 08:04 AM

 

Perhaps your predjudice towards premium scopes has clouded your vision!!

funnypost.gif

 

 

 

You and others on this forum have the  attitude that a scope has to be premium to deliver outstanding image quality and that simply isn't the case!!

troll.gif



#34 Asbytec

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Posted 23 October 2018 - 09:20 AM

...no difference in construction quality of the scope is somewhat hard to believe.

I tend to agree with the above. There is a difference in mechanical design and implementation. Mods seem the be the way of things. But, optically, I do believe they are getting better and more or less consistently so. Thankfully. Not premium, but nice. 

 

My current CAT is great, especially in modest climate and good seeing. My previous C11 was pretty good, but the mount was questionable. It worked, but I always felt like it was working too hard. My 12" Dob needed some work. It suffered from bearings that were way too smooth and had to be modded to prevent un commanded movement sans eyepiece. The spider was not taught enough. The mirror cell was okay, but not the best. Focusers were passable. That kind of thing. Needed modification to be better than stock. So, yea, there are glaring differences mechanically, IME. 




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