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Help me pick a larger planetary scope

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#1 infamousnation

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Posted 02 April 2018 - 11:07 AM

I have a takahashi fc100d on a cg4.  I want to get a larger scope to use on nicer nights when I am going to be out for several hours.  I care most about lunar and planetary.  I was thinking about getting a 10 inch dob or a cat that I can mount on my cg4.  What are my best options?



#2 Astrojensen

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Posted 02 April 2018 - 11:15 AM

A 10" dob will completely outclass any scope you can reasonably mount on your CG-4. 

 

 

Clear skies!
Thomas, Denmark 


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#3 Hesiod

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Posted 02 April 2018 - 11:19 AM

Well, on your CG4 you will not mount a "CAT" much more proficent that your FC: to have a noticeable step up from the FC you should really look into a 6" Intes, but these would be too heavy for the Cg4 for my taste.

Maybe you could "risk" the OMC140: there are very controversial opinions about its real prowess, but it is a definitely interesting telescope.

 

So the 10" Dob seems to me the safer bet.



#4 macdonjh

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Posted 02 April 2018 - 11:47 AM

+1 for the 10" Dob.



#5 jakecru

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Posted 02 April 2018 - 11:48 AM

Depending on budget, my first choice would be a Teeter 10" F/6 STS (solid tube dob) with Zambuto quartz primary mirror and antares 1/30 wave secondary. That is probably one of the best planetary scopes.
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#6 Jeff B

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Posted 02 April 2018 - 12:34 PM

The mount will be a pinch point for the aperture.  We are also not sure how much you are willing to fork over so that is another pinch point.

 

So, for your mount, I can recommend digging up a used Meade 7" Mak where the internal weight has been removed.  Many more here swear by them than at them when it comes to the optical quality and it's a great combination of aperture and focal length.

 

Just a thought.

 

Jeff 



#7 infamousnation

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Posted 02 April 2018 - 12:38 PM

So what's a good dob that's available new without waiting?  I know nothing about dobs



#8 fcathell

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Posted 02 April 2018 - 12:52 PM

Just a comment here - I've used a C8 on my CG-4 for visual and it works fine.  I wouldn't recommend this setup for imaging, however. You may have to check out a few C8s to get one optimum for planetary, but it can be done.

 

Frank 


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#9 junomike

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Posted 02 April 2018 - 12:56 PM

IME a 6" + Apo/ED or a 10" Teeter.



#10 starcanoe

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Posted 02 April 2018 - 01:05 PM

I just bought that 10 inch F8 mirror with nearly perfect wave error specs that was in the classifieds here....going to use my 12 inch f6 dob tube I was working on to mount it in. An oversized tube is fine with me....less issue with tube currents. Pretty excited about getting errrr done and Mars this summer.


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#11 outofsight

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Posted 02 April 2018 - 01:08 PM

So what's a good dob that's available new without waiting?  I know nothing about dobs

How about this, one of the best deals in astronomy, bang for buck, and usually available $200 to $300 cheaper, but I'm not finding any right now. I paid a little over a grand and know others have paid less than a grand. But there are a lot of 10" dobs around, goto, collapsible, or not.

 

http://www.skywatche...nian-10-254-mm/



#12 Pinbout

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Posted 02 April 2018 - 03:37 PM

a 12in dob that's been tested...https://www.cloudyni...f5-ultra-light/ grin.gif

 

Ronchi Star test

gallery_106859_355_30316.jpg


Edited by Pinbout, 02 April 2018 - 05:46 PM.

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#13 CHASLX200

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Posted 02 April 2018 - 05:51 PM

So what's a good dob that's available new without waiting?  I know nothing about dobs

Used is the best way to go.  There was a used 14.5" Starmaster on AM for under 5k.  Talk about a planet scope.  I had two and used over 1100x on my best nites.


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#14 Stephen Kennedy

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Posted 02 April 2018 - 05:52 PM

I think that the ideal set up would be a 10" F/7 Newtonian reflector on a GEM.  You would have to realize though that a good GEM for an OTA of that size is going to be large, heavy and expensive.  In addition, hefting an OTA of that size onto a GEM is going to be physically demanding.


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#15 Mike Lockwood

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Posted 02 April 2018 - 06:17 PM

I find that the ideal planetary telescope is the largest quality aperture that you will use frequently.

 

It can be fast or slow, in terms of f/#, so long as the optics are good.  Ideally the primary is not too thick so it can cool and be cooled in a reasonable time.  Proper mirror support and achieving and holding collimation are also very important.


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#16 acochran

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Posted 02 April 2018 - 06:23 PM

The best planetary scope I ever looked through belonged to telescope mirror maker Mike Spooner, viewing from his backyard in AZ (great seeing there!). We used his 6 inch F10 dob he made himself. He took forever to grind the mirror "perfect" and installed a tiny secondary mirror, for high contrast. The detail on Jupiter was jaw-dropping!

Andy


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#17 CHASLX200

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Posted 02 April 2018 - 06:53 PM

My best planet views came from all of my Zambuto and OMI 11 to 18" mirrors and all were F/5 or faster.  On the smaller size mirrors i like slower speeds in the 10" and smaller sizes.



#18 Pinbout

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Posted 02 April 2018 - 07:09 PM

My 8”f3.4 had big detailed views of Jupiter 

 

primary is only 5/8” thk 

 

https://youtu.be/yeFtBBRjuLM



#19 JKAstro

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Posted 02 April 2018 - 08:50 PM

While I've read on CN that some feel Teeter and others have surpassed Obsession, they've been making premium dobs for many years and have many happy customers.  I believe David Kriege keeps some parts on hand and is therefore able to turn around scopes in 1-2 months.  He is located in Lake Mills, WI, less than 2 hours from you, so you could pick up the scope instead of having it shipped.

 

http://www.obsession.../12.5/index.php



#20 Jon Isaacs

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Posted 02 April 2018 - 09:42 PM

I have a takahashi fc100d on a cg4.  I want to get a larger scope to use on nicer nights when I am going to be out for several hours.  I care most about lunar and planetary.  I was thinking about getting a 10 inch dob or a cat that I can mount on my cg4.  What are my best options?

 

My best planetary views have involved relatively large aperture Dobsonians.  That should be no surprise because I rarely look at the planets through other large aperture telescopes.  

 

But I am reluctant to advise anyone to jump in an purchase a premium quality or/and larger aperture Dobsonian without having spent a considerable amount of time observing with a Dob.  Some people love em, that's me.  Some people are just not Dob people...  A guy nearby invested in a new 11 inch Teeter with all the bells and whistles, the Zambuto mirror, a SIPs, (the Feathertouch with the built-in Paracorr.)  I don't think he ever actually used it, he just wasn't a Dob guy.  

 

I think Dob people are hands on people, tinkerers, happy to collimate the scope to get the best possible view, refractors and SCTs are black boxes, they are what they are and you just use them. Newtonians, you get involved.  The whole thermal equilibrium thing, the fans and all that. 

 

There is a lot to know about Newtonians.  If you are going to buy a fast, premium Newtonian, you are very likely going to want to invest in a set of TeleVue eyepieces and a Paracorr.  And a good set of collimation tools.  

 

Like I said, I am a Dob guy, I like the views they provide. It's good to know if you're a Dob type before getting too involved.

 

Jon


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#21 Pinbout

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Posted 02 April 2018 - 09:56 PM

To johns point going to a smaller newt first maybe a right first step cause dobs are...dobs

 

But chances getting good optics on imports are ...well ...@&$”$ especiallly the 2ndry’s

gallery_106859_3508_383875.jpg

 

Thats why why I learned to make my own

 

this is with the mirror uncoated and just hand holding the cell up to the eyepiece, and Jupiter is always a pita to expose correctly

 

 

https://instagram.com/p/BDo5eyOQki8/


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#22 Pinbout

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Posted 02 April 2018 - 10:00 PM

And getting a larger fast newt... I wish more people post their star tests in the cn gallery

 

when I use cardboard tubes the ota is so much lighter and a lot easier to mount

 

the thin primary cools so fast grin.gif

 

gallery_106859_3508_136394.jpg


Edited by Pinbout, 02 April 2018 - 10:01 PM.

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#23 sopticals

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Posted 02 April 2018 - 10:36 PM

I find that the ideal planetary telescope is the largest quality aperture that you will use frequently.

 

Totally concur.

 

Stephen.(45deg.S.)


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#24 barbie

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Posted 02 April 2018 - 10:53 PM

For me, my 6"F8 synta Dob with excellent optics is about the largest I can handle at this point in my 50 years of observing.  It is quite possible to get an import with excellent optics.  I've also had 8, 10, and 12 inch imported dobs which also had excellent optics and mechanicals right out of the box.  The only modification I have ever done was to flock opposite the focuser which greatly improved the contrast on planetary details.


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#25 Pinbout

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Posted 03 April 2018 - 05:54 AM

For me, my 6"F8 synta Dob with excellent optics is about the largest I can handle at this point in my 50 years of observing.  It is quite possible to get an import with excellent optics.  I've also had 8, 10, and 12 inch imported dobs which also had excellent optics and mechanicals right out of the box.  The only modification I have ever done was to flock opposite the focuser which greatly improved the contrast on planetary details.

 

How do you verify a statement like that? Star test? Bench tests?

 

i only ask that cause I looked thru a friends 12.5” discovery, great view of Saturn with his binoviewers.

different night his stars were bloats while mine were tight, i star tested it and it was more than 1/2~

the barlow in the Bino’s helped add correction for views of Saturn 


Edited by Pinbout, 03 April 2018 - 05:58 AM.



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