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SW180 Mak or GSO 8" CC

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#1 ScottW

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Posted 07 December 2021 - 07:17 PM

Hi,

 

Well I found out that my third attempt at buying three different scopes went south.  So it's seems to have come down the these two, a SW180 mak or the GSO 8" CC.  I like the SW for the F#15 and the GSO for the 8" diameter.  Both are about the same size and weight. I

 

I'm a 100% visual guy and will stay that way.  My main targets are double stars and the moon. I have both a F#7 refractor and a 8" F#6 dob. for other targets. My mount is a  Vixen SXD2 with the Vixen attachment for Losmandy plate which I also have.  My first concern is if the mount can handle these scope with ease, I don't like shakes when focusing.  Secondly is one inherently better quality wise?

 

Thanks for your time and input.

 

Scott 


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#2 doug mc

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Posted 07 December 2021 - 07:24 PM

Even if both scopes were on par optically, I would choose the mak, because if you insulate it, it is ready to go straight out the door. 


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#3 Richard O'Neill

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Posted 07 December 2021 - 07:44 PM

Ditto what Doug wrote plus a Mak doesn't produce diffraction spikes and the internal optical surfaces don't get dirty, nor will they need recoating.

 

Richard


Edited by Richard O'Neill, 07 December 2021 - 07:44 PM.

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#4 sevenofnine

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Posted 07 December 2021 - 07:57 PM

Considering what you want to do, the Mak seems like the better choice. Your mount is rated for 33 lbs. and the Mak is 19 lbs. so you have a little room if you go light on the accessories.  Best of luck to you! waytogo.gif


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#5 quilty

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Posted 08 December 2021 - 07:21 AM

Me to I join that line. Mak: outstanding, razorsharp views from the very beginning. The 8"CC is in reality a 7.34" one, so not much more light. Then you'll have to fuzz around with seeing, mirrors dewing up or, if you add an additional dewshield like I did, the oven-tube seeing-issue. No such thing with a well insulated Mak. Mak: 29%, CO, CC: 36% CO. A side by side test would reveal things.


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#6 macdonjh

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Posted 08 December 2021 - 05:59 PM

A couple of points about the classical Cassegrain: 

 

Cool down may not be an issue, depending on where you store your scope.  I store mine in a detached, unheated garage, so they're ready to go nearly immediately.

 

There will be diffraction with a Maksutov as well, but a diffraction ring rather than spikes.  You'll be hard pressed to notice either when viewing the moon, and you may not see them when viewing faint doubles.  Now, bright stars?  Of course you'll see either rings or spikes.

 

I've never had dew troubles with my closed-tube 8" classical Cassegrain, nor my truss OTA 14" classical Cassegrain.  I routinely had trouble with my C11 and always used both a dew shield and heater.  For reference, I observe on the Gulf Coast.

 

One trait the Maksutov has I would consider an inarguable advantage is collimation.  It will most likely be well collimated when it's delivered and will likely stay collimated forever.  The GSO classical Cassegrain may require collimation when you get it, and may need tweaking from time to time depending on how often you transport it.  Collimating a classical Cassegrain, to me, is much trickier than collimating either a Newtonian or an SCT.

 

Good luck with your choice.


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#7 Bigzmey

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Posted 08 December 2021 - 06:15 PM

I don't have much experience with GSO 8" CC, but SW 180mm Mak is an excellent scope for doubles, planets and lunar, you won't be sorry.


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#8 alnitak22

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Posted 08 December 2021 - 07:29 PM

I don't have much experience with GSO 8" CC, but SW 180mm Mak is an excellent scope for doubles, planets and lunar, you won't be sorry.

The 150 Synta Mak I recently purchased has definitely surpassed my expectations for lunar/ planetary. As Synta also makes the bigger 180 Mak, I can well imagine it’s even better.


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#9 quilty

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Posted 09 December 2021 - 04:58 AM

It's supposed do better concerning light grasp and definition but we never really know. And as it's a Gregorian style, f/15 is supposed to do better, too than f/12 concerning spherical correction. 

and diffraction rings. The CC shows brighter diffraction rings than the Mak for its CO is bigger. Plus spikes.

 

Collimation: You'll have to collimate both mirrors with the CC but I think that's no big issue once collimated you won't have to do that very often. And mechanically the sec mirror is fixed and controlled way better than in a SCT. Mirror cup is spring loaden and decoupled from the mirror bearing plate so no danger to drive astigmatism into the mirror when turning the  collimation screws too tight. Quite in fact, this CC is a pleasure to collimate compared to many other scopes, one of the good things about it.

But as stargazing is not just about collimation and includes observing, too, go for the Skymax, so many advantages optically and practically


Edited by quilty, 09 December 2021 - 07:29 AM.

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#10 ScottW

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Posted 10 December 2021 - 04:24 PM

Hi,

 

Thanks for all your input, I've ordered the 180 Skymax from Astronomics.  

Nothing to do now but wait.

 

Scott


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#11 Bigzmey

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Posted 10 December 2021 - 04:43 PM

You gonna love it! :)



#12 alnitak22

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Posted 10 December 2021 - 04:48 PM

Hi,

 

Thanks for all your input, I've ordered the 180 Skymax from Astronomics.  

Nothing to do now but wait.

 

Scott

Congrats!



#13 RajG

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Posted 10 December 2021 - 09:35 PM

Since you already have an 8in f/6 dob, I doubt that a 180Mak will show you much more (unless you got a bad copy of the dob). The dob is a true 8in so it gathers more light, but at high magnifications, push-to tracking can be annoying.

 

The main benefit of the Mak is that you can use it with a goto/tracking mount, plus the OTA is more compact. If you use Reflectix, the Mak won't need any cool down time.

 

In theory the dob has better contrast due to its smaller CO. It is also basically immune to dew, but being an open tube has a long cool down. Because it has a much shorter focal length, you can use it over a wider range of magnifications compared to the Mak. Personally I think the seated viewing position is more comfortable with a dob. 

 

I used to own a 6in f/8 dob and now I have a 150Mak on a goto mount (SSIV). The dob was fantastic but heavy and took up a lot of storage space. I never got good at starhopping - from my light polluted backyard, even finding M31 (Andromeda) was a challenge - half the time I would give up in frustration. I enjoy the convenience of goto & tracking, and that outweighs most other considerations for me, so I sold the dob. Optically & resolution-wise I can't really tell any difference except for the absence of diffraction spikes, which never really bothered me. 

 

Ymmv



#14 quilty

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Posted 11 December 2021 - 04:44 AM

Hi,

 

Thanks for all your input, I've ordered the 180 Skymax from Astronomics.  

Nothing to do now but wait.

 

Scott

good one



#15 Terra Nova

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Posted 15 December 2021 - 10:53 AM

I went through many of the same mental arguments when trying to decide between one of these two. It came down to the thick corrector plate, long cool-down time, and the fact that I can’t handle the thought of wrapping up a new Maksutov Cassegrain telescope in a tacky Reflectix insulating blanket, OR instead, getting an 8” CC with an effective aperture closer to 7” and with a host of seemingly known design flaws and the attendant need for multiple focal extensions and recollimation, and of course, with either, settling for a telescope with a large central obstruction. That’s why I decided on neither. Instead, my thought is to get a Takahashi Mewlon 180C. Yes, it costs more, but you’re getting known quality, and higher resale value if you don’t like it.


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#16 dweller25

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Posted 15 December 2021 - 11:06 AM

I went through many of the same mental arguments when trying to decide between one of these two. It came down to the thick corrector plate, long cool-down time, and the fact that I can’t handle the thought of wrapping up a new Maksutov Cassegrain telescope in a tacky Reflectix insulating blanket, OR instead, getting an 8” CC with an effective aperture closer to 7” and with a host of seemingly known design flaws and the attendant need for multiple focal extensions and recollimation, and of course, with either, settling for a telescope with a large central obstruction. That’s why I decided on neither. Instead, my thought is to get a Takahashi Mewlon 180C. Yes, it costs more, but you’re getting known quality, and higher resale value if you don’t like it.

You have written exactly what I found out and now I have the M180C smile.gif


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#17 quilty

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Posted 15 December 2021 - 11:30 AM

The Mewlon 180C is supposedly a great scope and it's beautiful and always worth a look. A side by side test with the skymax180 had the result that both scopes equal at optical performance. CO I think is smaller for the skymax. I'd go for the skymax, still. Pro's: No acclimatisation issue since Reflectix, no tube seeing problems, no mirror pollution, no mirrors dewing up (which all happens, so I learned, the GSO CC is quite similar to this regard), more reasonable price and (I think so) less value loss in time, better collimation stability (I think) Cons: heavier, not that stylish, 

 

You don't need to use tacky Reflectix, you can insulate the scope without leaving any traces (in case you would remove the insulation why ever). It's the opposite: Properly wrapped, it might appear brand-new years later because it's been so well protected.

 

And wrapping a Mewlon? People doubt that helps and at all, wouldn't that be a sin?



#18 pweiler

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Posted 15 December 2021 - 03:51 PM

Hi,

Well I found out that my third attempt at buying three different scopes went south. So it's seems to have come down the these two, a SW180 mak or the GSO 8" CC. I like the SW for the F#15 and the GSO for the 8" diameter. Both are about the same size and weight. I

I'm a 100% visual guy and will stay that way. My main targets are double stars and the moon. I have both a F#7 refractor and a 8" F#6 dob. for other targets. My mount is a Vixen SXD2 with the Vixen attachment for Losmandy plate which I also have. My first concern is if the mount can handle these scope with ease, I don't like shakes when focusing. Secondly is one inherently better quality wise?

Thanks for your time and input.

Scott


Hi Scott,

I may have commented in this thread before or else where to a similar subject…I have a CC8 (200mm) and some people, when they run the geometry numbers, come up with less than 8 inch aperture, but certainly more than a 6” (180mm) scope’s light gathering ability.

For visual, if your top priorities are the moon and double stars the cc8 does exceptionally well and will do well on many other types of objects. As you have mentioned a good mount will help especially with a cc that delivers a lot of magnification per millimeter of EP focal length used and could therefore also magnify “bounciness”.

Like most scopes with one or more mirrors, collimation may be required in a cc from time to time and since mirrors do not equalize to temperature differences instantaneously some cool down time may be required.

Personally I have not encountered those issues or issues with dew with a cc.

Hope that helps.

#19 Gaitaslibre

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Posted 16 December 2021 - 09:58 AM

A Mewlon 180 is a beautiful scope. I just wish they used a RACI finder instead of a straight tube and they are pricey compared to other scopes. I do understand the desire for high quality. I grew up with a little Questar available for my use and the quality was unmatched with anything else at the time. Someday I might get a 7 inch Questar Mak as my contribution to the industrial art world.

OTAs suffer from similar economics as other precision equipment; controlling tolerances to the last decimal point usually raises the costs exponentially. I just paid 3 times the cost for a high precision bench mill than other nominally equivalent models.

 

My experience and my Astro friends experiences with the GSO Dobson, and Cassegrain OTAs has been very good. Buying from a reputable vendor that tests the OTAs before shipping them rather than trying to save a few dollars, seems to be a good strategy. it’s best to test the optics and return the OTA if there are any issues. I know some folks love to tinker and get pleasure from trying to correct imperfections real or perceived, but it’s not for most of us.

 

Hanging a heavy optical train, such as large DLSRs with focal reducers, on the end of a GSO Crayford is probably asking too much. Yes, you can upgrade the focusers, but the costs for the aftermarket mods can erode the value proposition

 

I think the GSO Dobsons, RC and CC’s are very good buys, but they aren’t comparable in price or precision  to Takahashi, or Japanese Vixens. I also understand the personal choice to support Taiwanese companies over competing Mainland suppliers, given the state of the world. 
The good news is there are few bad choices these days. 


Edited by Gaitaslibre, 16 December 2021 - 10:04 AM.


#20 rmollise

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Posted 16 December 2021 - 10:01 AM

Hi,

 

Well I found out that my third attempt at buying three different scopes went south.  So it's seems to have come down the these two, a SW180 mak or the GSO 8" CC.  I like the SW for the F#15 and the GSO for the 8" diameter.  Both are about the same size and weight. I

 

I'm a 100% visual guy and will stay that way.  My main targets are double stars and the moon. I have both a F#7 refractor and a 8" F#6 dob. for other targets. My mount is a  Vixen SXD2 with the Vixen attachment for Losmandy plate which I also have.  My first concern is if the mount can handle these scope with ease, I don't like shakes when focusing.  Secondly is one inherently better quality wise?

 

Thanks for your time and input.

 

Scott 

 

I have no idea of the optical quality of the Chinese classical casses. However, assuming it's on a par with the Synta MCTs, I'd choose it. Even for "just" the Moon and planets and double stars, the additional aperture will make a big difference. ;)



#21 Terra Nova

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Posted 16 December 2021 - 11:50 AM

I have no idea of the optical quality of the Chinese classical casses. However, assuming it's on a par with the Synta MCTs, I'd choose it. Even for "just" the Moon and planets and double stars, the additional aperture will make a big difference. wink.gif

The problem is that as per Larry Carlino’s review and as others here have noted, the GSO CCs function at lower effective apertures that what is dictated by the actual diameter of their primaries. Hence, the 8” is actually working much more on par with a 180mm scope that is operating at full aperture.

 

https://www.cloudyni...assegrain-r3215


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#22 quilty

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Posted 16 December 2021 - 12:35 PM

not just this. (a side by side test of Mewlon 180 and GSO CC 186 :-) would be great, too, let alone the Mewlon 210) Quite similar optics, the Mewlon a bit lower weight.), so that's commonly known and already taken into account at price regard. The CC 7.34 is about half the price of the Mewlons's and about the same as the Skymax's, but how does it do optically? It could still be a good bargain just for the money (as the Skymax is). 

But more CO for the CC than the Mak. And all that tube seeing and dew stuff which you can avoid with the insulated Mak while not with the Mewlon.



#23 pweiler

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Posted 25 December 2021 - 11:45 PM

Me to I join that line. Mak: outstanding, razorsharp views from the very beginning. The 8"CC is in reality a 7.34" one, so not much more light. Then you'll have to fuzz around with seeing, mirrors dewing up or, if you add an additional dewshield like I did, the oven-tube seeing-issue. No such thing with a well insulated Mak. Mak: 29%, CO, CC: 36% CO. A side by side test would reveal things.


Tonight: 12/25/2021, Belvedere, IL, 27 Degrees F, 78% humidity. Dew and moisture falling all around. The 72mm refractor/finder scope dewed out of use. After 4+ hours of use, the CC8 primary and secondary had zero dew/moisture issues.

Edited by pweiler, 25 December 2021 - 11:47 PM.


#24 quilty

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Posted 26 December 2021 - 05:35 AM

Did you change anything about your CC8? Yesterday night was rather cold. Had the CC6 out of doors but was indoors most of the time. Took out the tube baffles and had a dewtube and the mirrors stayed free of dew. But all the times when I wasn't watching I put the lid on

Rather cold, the tube outside was -17° upper front end and -11 at the under rear cell, air was about -10.

So I took all anti dew precautions possible and there was no dew. But last time the mirrors dewed up all the upside of the tube was covered with ice, yesterday not at all. The night was dry.



#25 pweiler

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Posted 26 December 2021 - 10:30 AM

No Changes, stock Orion cc8 - the eyepiece case was covered in dew. My chairs were covered in dew, grass was soaked. My water resistant jacket had moisture on it. The refractor/finder dewed up. The cc8 mirrors remained spotless/normal and allowed me to photograph the trapezium with my iPhone which covered and blocked dew from falling on the EP. Edit: and no dew shield on the cc8. Standard dew shield on the skywatcher refractor. Setup was a few feet from a swampy area with large pooling water and flowing stream.

https://www.cloudyni...7-belvidere-il/

Edited by pweiler, 26 December 2021 - 12:45 PM.



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